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The Safety of Low-Dose Larrea tridentata (DC) Coville (Creosote Bush or Chaparral): A Retrospective Clinical Study

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To determine whether internal use of low doses of Larrea tridentata tincture or topical applications of this traditional herbal medicine are safe. Retrospective review of all people prescribed Larrea for internal or for topical use over a 22-month period. A general naturopathic practice in Sedona, Arizona. Thirteen patients were identified for whom Larrea tincture for internal use was prescribed. An additional 20 female and 3 male patients were identified for whom an extract of Larrea in Ricinus communis (castor) oil for topical use was prescribed. No patient had any history of liver disease. Larrea was prescribed as part of the usual care of each patient. In all cases it was given as either part of a complex herbal formula individualized for each patient containing less than 10% Larrea tincture or as an extract in Ricinus oil for topical use. Serum liver enzyme levels as well as blood urea nitrogen and creatinine levels, glucose levels, electrolytes, bilirubin levels, iron levels, ferritin levels, lipid levels, and complete blood count (CBC) were available for analysis in four patients; general clinical history and physical examination findings were relied on in all other cases. The four patients with complete before and after blood chemistry panels and CBC had no indication of liver damage from use of Larrea. This included one patient who was taking medications with significant potential for hepatotoxicity. No patient in the study, whether using Larrea for short term or long, internally or externally, showed any sign of organ damage during the period of follow-up. Relatively small intakes of Larrea tincture, or topical application of extracts in Ricinus oil, are safe when prescribed by a clinically trained botanical prescriber. Larrea should be used with caution in persons with a history of previous, or current, liver disease. It may be preferable to avoid the use of Larrea capsules because they have been associated with potentially dangerous overdosing.
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THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE
Volume 7, Number 2, 2001, pp. 175–185
Mary Ann Liebert, Inc.
The Safety of Low-Dose
Larrea tridentata
(DC) Coville (Creosote Bush or Chaparral):
A Retrospective Clinical Study
SILENA HERON, N.D., and ERIC YARNELL, N.D.
ABSTRACT
Objective:
To determine whether internal use of low doses of
Larrea tridentata tincture or top-
ical applications of this traditional herbal medicine are safe.
Design: Retrospective review of all people prescribed
Larrea for internal or for topical use over
a 22-month period.
Setting/Location: A general naturopathic practice in Sedona, Arizona.
Subjects: Thirteen patients were identified for whom
Larrea tincture for internal use was pre-
scribed. An additional 20 female and 3 male patients were identified for whom an extract of
Lar-
rea in
Ricinus communis (castor) oil for topical use was prescribed. No patient had any history of
liver disease.
Interventions: Larrea was prescribed as part of the usual care of each patient. In all cases it
was given as either part of a complex herbal formula individualized for each patient containing
less than 10%
Larrea tincture or as an extract in
Ricinus oil for topical use.
Outcome Measures: Serum liver enzyme levels as well as blood urea nitrogen and creatinine
levels, glucose levels, electrolytes, bilirubin levels, iron levels, ferritin levels, lipid levels, and
complete blood count (CBC) were available for analysis in four patients; general clinical history
and physical examination findings were relied on in all other cases.
Results: The four patients with complete before and after blood chemistry panels and CBC
had no indication of liver damage from use of
Larrea. This included one patient who was tak-
ing medications with significant potential for hepatotoxicity. No patient in the study, whether
using
Larrea for short term or long, internally or externally, showed any sign of organ damage
during the period of follow-up.
Conclusions: Relatively small intakes of Larrea tincture, or topical application of extracts in
Ricinus oil, are safe when prescribed by a clinically trained botanical prescriber. Larrea should
be used with caution in persons with a history of previous, or current, liver disease. It may be
preferable to avoid the use of
Larrea capsules because they have been associated with potentially
dangerous overdosing.
175
INTRODUCTION
Aseries of case reports in the mid-1990s ap-
peared in the literature implicating the
leaves, flowers, and twigs of Larrea tridentata
(DC) Coville (creosote bush or chaparral) as a
possible cause of liver damage (Sheikh et al.,
1997). Larrea has no previously recorded his-
tory of causing hepatotoxicity despite wide use
as a medicinal plant throughout the south-
Naturopathic Family Health Care, Sedona, AZ, and Botanical Medicine Academy, Seattle, WA.
western United States and northern Mexico
(Moore, 1989; Brinker 1993/4; Kay, 1996). In
fact, it has been described as having a benefi-
cial impact on liver metabolic functions ac-
cording to empirical use (Moore, 1989). A
French patent has been issued on a key ingre-
dient in
Larrea known as nordihydroguaiaretic
acid (NDGA) describing its use for persons
with alcoholic liver disease (Oliveto, 1972).
Larrea is an ancient plant, with individual
specimens having been carbon dated to an age
of approximately 9,000 years (Nabhan, 1985).
Others have claimed Larrea stands may be as
old as 13,000 years (Moore, 1989). These bushes
grow to be 6 to 18 feet tall with small, dark
green, greasy, leathery leaves that turn bright
green after a rain. The small yellow flowers ma-
ture into white, fuzzy seed capsules containing
five seeds. Creosote is a poisonous, oily liquid
obtained by distillation of coal tar that has a
scent similar to that of Larrea, hence the com-
mon name creosote bush. Creosote is otherwise
unrelated to Larrea. Table 1 shows the con-
stituents found in Larrea and their actions
where known.
Larrea has been known by several common
names besides creosote bush. The name chap-
arral is perhaps the most common, although
this is misleading. Chaparral is an ecological
zone where plants are drought-, sun-, and fire-
adapted.
Larrea is an xerophyte (dry land plant)
and rarely grows in the chaparral (Nabhan,
1985). Common Spanish names include
hediondilla (“little smelly one”) and
gobernadora
(“governess”). It is called
gobernadora in part be-
cause
Larrea stands can dominate large regions
in the desert at elevations below 4,000 feet.
Larrea has been used as medicine for many
centuries. Larrea pollen has been identified in
coprolites from ancient sites in the southwest-
ern United States (Kay, 1996). Numerous uses
have been mentioned for Larrea in the ethno-
botanical literature (Moore, 1989; Brinker,
1993/4; Kay, 1996; Curtin and Moore, 1997).
Only the most common uses and those that ap-
pear in multiple sources will be reported here.
These uses generally conform to modern clini-
cal experiences with use of Larrea. Internally
and topically it has been used to treat abdom-
inal complaints with problems in gastrointesti-
nal and pelvic organs including dyspepsia,
dysmenorrhea, and premenstrual syndrome.
Rheumatic and autoimmune conditions, arthri-
tis, and back pain stand out as common uses of
topical
Larrea. Additional topical uses, particu-
larly of fomentations or powders, are to treat
minor wounds, skin infections such as im-
petigo and chicken pox, and gingivitis. Several
HERON AND YARNELL
176
TABL E 1. LARR EA T RID EN TA TA CON STITUE NT S AN D THEIR AC TIO NS
Class of constituents Specific constituents Reported actions in
Larrea
Lignans Nordihydroguaiaretic acid Antioxidant. Antimicrobial, antifungal, and
(NDGA), norisoguaiacin, antiviral. Inhibit electron transport chain in
dihydroguaiaretic acid, etc. mitochondria. Inhibits phospholipase A2,
cyclooxygenase, and lipoxygenase. Cytotoxic
and anticarcinogenic. Hypoglycemic (Luo et
al., 1998). Analgesic (Bergel, 1955).
Flavonoid glycosides Apigenin methyl ester Inhibit NADH oxidase, phospholipase A2, and
quercetin, dimethoxyl morin lipoxygenase. Cytotoxic (DMM). Inhibit
(DMM), kaempferol, etc. replication of RNA viruses.
Triterpene saponins Larreagenin A, larreic acid, etc. Unknown
Volatile terpenoids a-Pinene, limonene, linalol, Unknown
camphor, benzaldehyde,
farnseol, etc.
Sterols b-Sitosterol, campesterol, etc. Unknown
Protein Amino acids Nearly as high quality as alfalfa once resin is
removed.
Carbohydrates Dextrin, glucose, sucrose Nutritive
Lipids Wax esters Unknown
Vitamins Vitamin C, carotenoids Nutritive
Minerals Minerals Nutritive
Source: Brinker 1993/4, unless otherwise noted. Used with permission of the author.
native peoples used it as deodorizer on the feet
and in the armpits. Its internal use is frequently
mentioned as a treatment for those with upper
respiratory tract viral infections, bronchitis,
coughs, urinary tract infections, dyspepsia, ab-
dominal cramps, enteritis, dysentery, and can-
cer. Finally, it has been reported to improve the
quality of blood lipids, apparently supported
by clinical trials conducted in Latin America
(Moore, 1989). There are historical mentions of
use of
Larrea as an abortifacient, although it was
also used as a means to increase fertility (Kay,
1996). Until more information is available, in-
ternal use of
Larrea should be avoided in preg-
nancy.
Toxicity caused by
Larrea ingestion is multi-
factorial in nature. Contributing factors are
consumption of excessively large amounts re-
lated to the use of encapsulated products, idio-
syncratic reactions, and possibly adulteration.
The traditional way to take creosote bush is as
a tea. The flavor is strong and often considered
disagreeable, greatly limiting the amount that
can be ingested. Capsules allow people to take
much greater amounts easily, and taste is not
a limiting factor. Powdered herbs were not tra-
ditionally used as medicines for the most part,
although it is unclear if Larrea in this form is
particularly more of a problem than tea or tinc-
ture.
An idiosyncratic effect of
Larrea
on the livers
of uniquely susceptible individuals also cannot
be ruled out. This would, however, suggest the
problem was mostly with the patient and not
the medicine—idiosyncratic reactions can hap-
pen in response to any substance. Supporting
this contention is the lack of any study to date
that has identified any constituent of
Larrea that
causes the adverse effects seen in reported
cases of poisoning in vitro, in laboratory ani-
mals, or in humans.
Finally, adulteration or contamination of the
Larrea products reported in other case series
cannot be ruled out based on the evidence pro-
vided (Sheikh et al., 1997). It is possible that
some of the instances of reported
Larrea-related
liver damage were actually caused by micro-
bial contamination (such as aflatoxins) or the
presence of some other botanical that actually
caused liver damage. In other instances, this
has been documented to occur. For example,
one report that originally blamed
Scutellaria la-
teriflora (American skullcap) for causing liver
damage in humans actually turned out to be
adulterated with Teucrium chamaedrys (ger-
mander) or a similar species (MacGregor et al.,
1989). Germander contains known hepatotoxic
pyrrolizidine alkaloids.
Presented here is a retrospective review of
patients seen at our clinic in the past 2 years
who were treated with lower doses of Larrea.
The duration of treatment was variable. In
these cases, the leaves and flower were deliv-
ered as a tincture (hydroethanolic extract) as
7%–18% of complex formulae including 8–10
other botanical extracts. It is the authors’ hy-
pothesis that a tincture more closely approxi-
mates the traditional use of Larrea as a tea
compared to powdered leaves delivered in cap-
sules, and that low doses (less than 1 mL daily)
of tincture taken for as long as 5 months are
without discernable toxicity. The use of com-
binations of herbs was also practiced in tradi-
tional herbalism, as reflected by this tendency
among Hispanics who almost certainly learned
the use of local plants from native peoples
(Curtin and Moore, 1997). This is true even in
persons at substantial risk of developing liver
injury, such as one patient who was taking po-
tentially hepatotoxic drugs concomitantly.
Data will also be presented to show that topi-
cal use of
Larrea is safe.
A small body of evidence contradicts our the-
ory that aqueous extracts of
Larrea are nontoxic.
One case report involved a woman who drank
3 to 4 cups of
Larrea tea over a 3-month period
along with 5 to 6 cups of
Tabebuia spp. (taheebo
or pau d’arco) bark tea over a 6-month period
and developed renal cell carcinoma (Smith et
al., 1994). Causation was not proven and it
seems unlikely the tumor could have devel-
oped over such a short period of time. A wors-
ening or improvement of the cancer cannot be
ruled out based on the data in this case report.
Three patients of 18 in the Archives of Internal
Medicine case series who developed adverse ef-
fects related to
Larrea consumed this herb pri-
marily as a tea (Sheikh et al., 1997), however,
only 1 of 13 cases with liver toxicity used it in
the form of a tea. Precise dose information on
the 3 patients with adverse effects who drank
Larrea tea was not provided. Thus, there is a re-
SAFETY OF LARREA TRIDENTATA 177
mote possibility that Larrea may entail some
risk even when taken as an aqueous extract.
Supporting our hypothesis is a trial in which
59 patients with terminal cancer were given ei-
ther 16 to 24 ounces of
Larrea tea or 250 to 3,000
mg NDGA daily (Smart et al., 1970). None of
these patients developed jaundice or other
signs of liver damage, although some partici-
pants reported nausea and vomiting, diarrhea,
abdominal cramps, rash, stomatitis, and fever
(in order of decreasing frequency). Intramus-
cular injection of NDGA at a dose of 400 mg/kg
daily for as long as 6 months has not been re-
ported to cause liver damage or other toxic ef-
fects (Bergel, 1955). This dose, assuming a 10%
NDGA content of
Larrea, would be equivalent
to 280 g of leaf daily (approximately 9 ounces
of tincture) for a person weighing 70 kg
(Brinker, 1993/4). There is evidence that
Larrea
resin (containing NDGA among other pheno-
lic compounds) has antifeedant activity in in-
sects; the application of this information to hu-
mans is of unknown importance (Rhoades,
1977). NDGA is therefore an unlikely candidate
as a toxic constituent in
Larrea. Other possible
toxic constituents have not been evaluated.
MATERIALS AND METHODS
A computer-generated list of all sales of
Lar-
rea tridentata in any form from the clinic’s dis-
pensary was utilized to identify patients to
whom this herb was sold between January 1,
1997 and October 15, 1998. Records on each pa-
tient were then cross checked to confirm the
prescription and to determine the details of the
patient’s case. All persons identified were in-
cluded in the analysis. The maximum possible
dose taken was determined based on the
amount of product sold; in some cases the pa-
tient may not have taken all of the
Larrea sold
to them.
Raw material for
Larrea tincture was picked
from the wild locally and confirmed by
organoleptic assay (use of sight, smell, and
taste to identify and evaluate the quality of the
herb) to be quality specimens for medicinal
preparation by one of us (S.H., who has 25
years experience in the field of botanical med-
icine), on the basis of the presence of resinous
coating, morphology, odor, and taste. Only
green new growth with flowers present and
prior to seed production was selected from
healthy looking plants. A voucher specimen
was retained on site. The undried leaves and
flowers were lightly ground in 90% ethanol and
10% distilled water at a weight-to-volume ra-
tio of 1:2.5. A high ethanol content is used be-
cause this most efficiently extracts resinous
compounds, particularly NDGA (Duisberg et
al., 1949). NDGA extraction in water is low by
comparison (Obermeyer et al., 1995). The re-
sultant product was allowed to macerate (soak)
for at least 14 days out of direct sunlight. The
material was then pressed and filtered to re-
move any solid sediment and the final tincture
packaged in amber glass bottles.
A portion of some raw Larrea material was
air-dried in a paper bag at room temperature.
This technique works only in arid climates such
as Arizona. It was mixed with oil from
Ricinus
communis (castor) seed in a weight-to-volume
ratio of approximately 1:3. This mix was left to
digest at 10 to 115°F for 48 hours. The mate-
rial was then cooled and pressed to remove
solid matter; it was not filtered. The final oil
was stored in amber glass bottles.
Twelve patients (12), 8 females and 4 males,
who took any amount of Larrea during the
study period were identified. Twenty-three pa-
tients (23), 20 females and 3 males, who used
any amount of
Larrea in
Ricinus oleum topically
during the study period were identified.
RESULTS
A total of 12 patients had
Larrea for internal
use prescribed for them during the study pe-
riod. A summary of patient data and levels of
serum liver enzymes and other indicators of
liver health is presented in Table 2 for the four
patients with complete data available. One pa-
tient took relatively similar doses to these four
cases but did not have follow-up blood
chemistries and CBC. The remaining 8 patients
took much smaller doses and/or blood values
were not available. Some of the tests reported
in Table 2 were chosen because these were used
in one retrospective series of 13 hepatitis cases
previously reported (Sheikh et al., 1997). In the
HERON AND YARNELL
178
patients in that study, most had elevated serum
alanine aminotransferase (ALT), aspartate
aminotransferase (AST), alkaline phosphatase
(ALP), and total bilirubin (TB) levels. Liver biop-
sies were not performed on any of the cases pre-
sented here as none had any evidence of liver
damage related to creosote bush ingestion.
Further information about the four patients
with the most complete data and who took the
largest doses are presented below.
Case 1 (J.C.)
This 49-year-old white woman was given a
botanical formula for allergies containing 8%
Larrea starting on March 24, 1997. The complete
formula is listed in Table 3. She previously re-
ported having tachycardia when taking a pseu-
doephedrine-containing product, so Ephedra
sinica (ma haung, an ephedra-containing botan-
ical often used to treat allergic patients) was not
included. The patient purchased a total of 14
ounces of formula over a period of 4 months.
The prescribed dose was 5 to 10 mL every 30
to 120 minutes. She reported dizziness when
taking 10 mL of the formula by June 4, 1997
and was instructed to decrease the dose. On
July 8, 1997 the patient reported that taking the
formula four times daily did not help her al-
lergies but she had no adverse effects. There-
fore, assuming that the patient took all the for-
mula she bought (and she may not have by her
own admission), the maximum amount of
Lar-
rea tincture she took was 32 mL (1 ounce) over
3.5 months.
The patient was also taking esterified estro-
SAFETY OF LARREA TRIDENTATA 179
TABL E 2. SUMMARY OF PATIENT DA TA A ND MA JOR LIVER FUNCTION TESTS
AST in ALT in LDH in TB in ALP in
Patient Gender Age DoseaTest date U/LbU/LcUI/Ldmg/dLeU/Lf
J.C. F 49 32 mL 2/13/97 13 37 116 1.6 63
8/1/97 21 24 196 1.0 45
S.R. F 52 240 mL 11/26/96 16 23 103 0.7 50
5/23/97 17 10 118 0.6 56
B.L. M 53 34 mL 8/6/98 16 23 174 0.7 74
11/13/98 32 34 146 0.6 81
D.D. F 51 138 mL 1/14/97 15 14 126 0.8 65
1/5/98 20 21 122 0.5 85
ALT, alanine aminotransferase; ALP, alkaline phosphatase; AST, aspartate aminotransferase; TB, total bilirubin.
aMaximum, total dose possible of
Larrea tincture the patient took.
bReference range is 0–41 U/L (except 2/13/97 test for patient J.C., when the range was 15–37 U/L).
cReference range is 0–45 U/L (except 2/13/97 test for patient J.C., when the range was 30–65 U/L).
dReference range is 100–230 U/L (except 2/13/97 test for patient J.C., when the range was 100–200 U/L).
eReference range is 0.0–1.4 mg/dL (except 2/13/97 test for patient J.C., when the range was 0.1–1 mg/dL).
fReference range is 20–130 U/L (except 2/13/97 test for patient J.C., when the range was 13–130 U/L).
TABL E 3. ALLERGY FORMULA
Percent of Ethanol, glycerin
Latin name Common name Part usedaformula content (%)
Euphrasia spp. Eyebright Herba 16 25, 0
Sambucus nigra Elder Flos 16 25, 0
Solidago virgaurea Goldenrod Flos 16 45, 10
Urtica dioica Stinging nettle Herba 12 0, 75
Salvia officinalis Sage Herba 8 0, 75
Cochlearia amoracia Horseradish Radix 8 55, 10
Hydrastis canadensis Goldenseal Radix 8 65, 10
Larrea tridentata Creosote bush Herba 8 90, 0
Plantago major Broadleaf plantain Folia 8 30, 10
aTranslation of Latin terms; Flos, flowers; Folia, leaves; Herba, aboveground parts of the plant; Radix, root.
gens and fluticasone nasal spray. Esterified es-
trogens were later discontinued and triple es-
trogen (80% estriol, 10% each estradiol, and es-
trone) and sublingual micronized progesterone
were substituted. Her dietary supplements in-
cluded calcium/magnesium, vitamin E, vita-
min C with flavonoids, glucosamine sulfate,
colloidal minerals, spirulina, vitamin B12, folic
acid, b-carotene, bromelain, quercetin, a sepa-
rate complex herbal formula without Larrea,
and
Equisetum arvense (horsetail) herb glycerin
extract. Echinacea angustifolia (purple cone-
flower) root tincture,
Taraxacum officinale (dan-
delion) root tincture, and
Crataegus oxyacantha
(hawthorn) fluid extract were also prescribed
during the period the patient was taking al-
lergy formulas.
J.C. had an elevated total bilirubin level of
1.6 mg/dL on February 2, 1997 before she
started taking
Larrea. This level decreased to 1
mg/dL approximately 4 months after she
started taking Larrea. She had a low white
blood cell count (WBC) on February 13, 1997 of
2.68 thousands per cubic millimeter that in-
creased to 3.1 by August 8, 1997. Her lympho-
cyte percentage was high at 48.5% and her
granulocyte count low at 1.14 thousand per cu-
bic millimeter on February 13, 1997 but both
normalized by August 8, 1997. She had a lower
serum iron level of 35 mg/dL on August 8,
1997. No other abnormalities were detected on
routine testing. There was no indication of liver
disease at any time; her serum liver enzyme
levels are recorded in Table 2.
Case 2 (S.R.)
Starting on January 1, 1997 this 52-year-old
white woman had the herbal formula described
in Table 3 prescribed for her to reduce respira-
tory symptoms of allergies for which she was
taking loratidine. The prescribed dose was 5
mL three times daily. She continued refilling
this formula through May 1997. If she took the
entire amount of allergy formula prescribed
(which she stated she did and that her past his-
tory strongly supported), her maximum dose
of Larrea tincture would have been 240 mL (8
ounces) over approximately 5 months.
S.R. was taking clonazepam and zolpidem,
and started valproic acid in May 1997 as
needed for manic symptoms. Thyroid United
States Pharmacopoeia was prescribed to treat
her hypothyroidism. Her nutritional supple-
ments included coenzyme Q10, magnesium
potassium taurine, lysine, vitamin C, flavo-
noids, a multivitamin/mineral, b-carotene, a
complex botanical formula for respiratory in-
fections, Echinacea angustifolia (purple cone-
flower) root tincture, spirulina, a botanical
cough syrup, calcium, hydrolyzed fish protein,
soy protein powder, phosphorylated serine
and ethanolamine, Silybum marianum (milk
thistle) seeds, a complex herbal formula,
Salvia
officinalis (sage) leaf glycerin extract,
Lactobacil-
lus and
Bifidobacterium , and vitamin E.
Despite the concomitant use of potentially
hepatotoxic medications there was no sign of
liver disease at any time while S.R. was taking
Larrea. The levels of her serum liver enzyme
levels are reported in Table 2. She had a chronic
low WBC (2.3 thousand per cubic millimeter on
November 11, 1996 and 2.5 on May 5, 1997),
low platelet count (123 thousand per cubic mil-
limeter on November 11, 1996 and 133 on May
5, 1997), and low high-density lipoprotein
(HDL) cholesterol level (42 mg/dL on Novem-
ber 26, 1996 and 40 on May 5, 1997). These were
likely related to her medications. Her thyroid-
stimulating hormone (TSH) level was high at
5.37 mIU/L on November 26, 1996 and 14.6 on
May 15, 1997, necessitating alteration of her
thyroid USP dose.
Case 3 (B.L.)
On August 4, 1998 this 53-year-old, afebrile,
white man presented with painful axillary lym-
phadenopathy on the left side. He was given a
botanical formula that is detailed in Table 4.
Initially he was instructed to take 5 mL of this
formula four times daily while applying oil of
Phytolacca decandra topically, doing lymphatic
massage, and taking a protein powder supple-
ment. There was 90% improvement by August
14, 1998 and he stopped the formula.
The problem flared again on August 21, 1998
and continued despite reinstatement of the
formula at a dose of 5 mL three times daily.
Penicillin VK was prescribed at a dose of 500
mg four times daily for 10 days, along with ben-
tonite clay packs, and
Larrea in
Ricinus oil top-
HERON AND YARNELL
180
ically. The patient reduced the dose to only 5 mL
once daily on approximately August 31, 1998
(the patient’s memory was inexact as to the
date). His maximum total internal dose of
Lar-
rea tincture was 34 mL (just over 1 ounce) over
a period of approximately 40 days. Because the
lesion did not completely resolve even with the
antibiotic, the patient was referred for lymph
node biopsy. Local spread of malignant
melanoma was diagnosed, later shown to have
metastasized to the lungs on a computed tomo-
graphic scan. The primary tumor was a subcu-
taneous nodule over the left scapula. Melanoma
is known to take many years to develop and thus
it is higly unlikely that
Larrea had any role in the
occurrence of this cancer, given that it was ad-
ministered after metastasis of the primary tumor
had already occurred.
On August 29, 1998, the patient had an ele-
vated sedimentation rate of 38 mm/h, an ele-
vated WBC of 14.3 thousand per cubic mil-
limeter and a low lymphocyte percent of 12. On
9/29/98 the sedimentation rate was down to
11 while his WBC remained high at 11.6 with
a granulocyte count of 8.6 thousand per cubic
millimeter. The lymphocyte percent stayed low
at 14 and the monocyte percent was now low
at 9.7. Again there was no sign of liver damage
related to his intake of
Larrea. The specific val-
ues of his serum liver enzyme levels are given
in Table 2.
Case 4 (D.D.)
On May 20, 1997 this 51-year-old female was
given two weight management formulas, both
containing
Larrea. The basic formula for both is
described in Table 5, although one version also
SAFETY OF LARREA TRIDENTATA 181
TABLE 4. LYM PHO GO GU E FORMULA
Percent of Ethanol, glycerin
Latin name Common name Part usedaformula content (%)
Ceanothus greggii Red root Radix 18 55, 10
Echinacea angustifolia Echinacea Radix 14 45, 10
Phytolacca decandra Poke Radix 11 55, 10
Arctium lappa Burdock Radix 11 35, 10
Fouquieria splendens Ocotillo Cortex 7 85, 10
Commiphora molmol Myrrh Resin 7 90, 0
Berberis aquifolium Oregon grape Cortex radii 7 45, 10
Taraxacum officinale Dandelion Radix 7 40, 10
Larrea tridentata Creosote bush Herba 7 90, 0
Baptisia tinctoria Wild indigo Radix 7 65, 10
Tabebuia spp. Pau d’arco Cortex 3 50, 10
aTranslation of Latin terms: Cortex, bark; Cortex radii, bark of root; Herba, aboveground parts of the plant; Radix,
root.
TABL E 5. WEIG HT MA NAGEM EN T FORMULA
Percent of Ethanol, glycerin
Latin name Common name Part usedaformula content (%)
Stellaria media Chickweed Herba 15 0, 75
Corynanthe yohimbe Yohimbe Cortex 15 50, 10
Fucus vesiculosus Bladderwrack Thallus 15 25, 10
Larrea tridentata Creosote bush Herba 10 90, 0
Trigonella foenum-graecum Fenugreek Semen 10 25, 10
Berberis aquifolium Oregon grape Radix 10 45, 10
Taraxacum officinale Dandelion Folia 10 30, 10
Salix nigra Willow Cortex 5 25, 0
Zingiber officinale Ginger Rhizoma 5 90, 0
Eleutherococcus senticosus Eleuthero, Siberian Radix 5 40, 0
ginseng
aTranslation of Latin terms: Cortex, bark; Folia, leaves; Herba, aboveground parts of the plant; Radix, root; Rhi-
zoma, rhizome (underground stem); Semen, seed; Thallus, soft frond of a sea vegetable.
contained Ephedra sinica
(ma huang) and
Cola
vera (kola nut). The dose in each case was 5 mL
three times daily. On May 29, 1997, the patient
adjusted the dose to 5mL daily of the formula
without ma haung or kola nut in order to avoid
any dependence on stimulants. She bought a
total of 48 ounces of the formula for a total,
maximum possible dose of Larrea of 138 mL
(just over 4 ounces) over a period of approxi-
mately 3 to 4 months, although it is unclear
when exactly the patient completed taking the
formula.
She was taking no known hepatotoxic drugs
and had no history of liver disease. Her nutri-
tional supplements included garlic capsules,
soy protein powder, a complex botanical for-
mula without Larrea, vitamin C, a multivita-
min/mineral, vitamin E, and calcium/magne-
sium. No sign of liver injury appeared at any
time during the course of her use of the weight
management formula containing Larrea. Her
serum liver enzyme levels are reported in Table
2. She had an elevated total cholesterol level of
228 mg/dL on January 14, 1997 and elevated
low-density lipoprotein (LDL) cholesterol level
of 159 mg/dL. Her neutrophil percent was low
at 37 on January 14, 1997 while her lymphocyte
percent was high at 58. One year later, on Jan-
uary 5, 1998, her total cholesterol level was 264
mg/dL, her triglyceride level was elevated at
266 mg/dL, and her LDL level was 159 mg/dL.
Her neutrophil and lymphocyte percentages
had normalized.
Other patients
One patient (J.H.) first took a formula con-
taining
Larrea on February 21, 1996. Table 6 lists
the components of her formula, used as part of
therapy for a dental infection. She used 5 mL
every 2 to 3 hours as needed. The same pre-
scription was made for other dental infections
on December 9, 1996 and April 28, 1997. Her
total maximum possible dose of Larrea was
therefore 215 mL periodically over a period of
more than 14 months. The patient moved out
of state and so it was unclear if she continued
using the Larrea-containing formula beyond
approximately 15 months. She had no history
of liver disease and serum liver enzyme levels
measured on January 29, 1996 showed no ele-
vations. Follow-up laboratory work was not
available. She developed no signs or symptoms
of liver damage.
The remaining eight patients did not have
complete documentation or took less than 30
mL of
Larrea tincture. These patients are sum-
marized in Table 7. None of these patients de-
veloped clinical symptoms suggestive of Lar-
rea-induced hepatotoxicity. No other adverse
effects could be attributed to the
Larrea in any
case.
Larrea in
Ricinus oil for topical use during the
study period was prescribed for a group of 20
female and 3 male adult patients. Indications
included dysmenorrhea, cancer, pain, benign
parotid mass, myalgia, and genital herpes sim-
HERON AND YARNELL
182
TABL E 6. HE RB AL ANT IBIO TIC FORMULA
Percent of Ethanol, glycerin
Latin name Common name Part usedaformula content (%)
Echinacea angustifolia Echinacea Radix 18 45, 10
Larrea tridentata Creosote bush Herba 18 90, 0
Allium sativum Garlic Bulbus 18 0, 75
Hydrastis canadensis Goldenseal Radix 9 65, 10
Commiphora molmol Myrrh Resin 9 90, 0
Berberis aquifolium Oregon grape Radix 9 45, 10
Cochlearia amoracia Horseradish Tuber 5 55, 10
Phytolacca decandra Poke Radix 5 55, 10
Baptista tinctoria Wild indigo Radix 5 65, 10
Eucalyptus globulus Eucalyptus Folia 5 45, 10
aTranslation of Latin terms: Bulbus, bulb; Herba, aboveground parts of the plant; Radix, root; Tuber, underground
storage organ.
plex. No patient reported an adverse effect ex-
cept for one woman who used it repeatedly in
combination with an oil infusion of
Hypericum
perforatum (St. John’s wort) flowers for genital
herpes. The use of the oils caused a spreading
of the lesions, as is known to occur with med-
ications of any kind in an oil suspension. This
was seen as a prescribing error and not an ad-
verse effect of the herbs in question, given that
tinctures of the two herbs have been observed
in practice to have a definitive healing effect.
Acyclovir led to rapid reduction in symptoms
in the patient cited above. No patient showed
any sign of organ damage while using topical
Larrea in
Ricinus oil.
DISCUSSION
Although it is limited in scope, our report
suggests low does (,1 mL daily of tincture) of
Larrea are safe for internal use when recom-
mended by an experienced botanical prescriber
in a naturopathic clinical context. Topical ap-
plication of this plant in Ricinus oil was also
found to be without negative effect directly at-
tributed to the Larrea. These analyses are not
intended to document efficacy.
All of the materials were prepared and dis-
pensed by the prescribing physicians them-
selves. This eliminates the possibility of adul-
teration or misidentification, incidental or
intentionally, that is unfortunately common in
the rapidly expanding mass market for botan-
ical medicines. It also helps ensure that a high-
quality source material is utilized, although it
would likely be beneficial to implement chro-
matographic analysis of multiple constituents
in each batch to confirm this. Our methods
probably correspond more closely with medi-
cinal use of Larrea tea by Native Americans
than taking encapsulated, powdered herb.
Nevertheless, there is still some difference be-
tween the 90% ethanol extract utilized in our
study and traditional aqueous extracts. The
lack of toxicity found in our study correlates
with the lack of reports of toxicity of tea. Over-
all the main conclusion again appears to be that
avoiding overdoses of any form is likely to be
the most important factor in preventing ad-
verse effects.
The use of complex botanical mixtures or for-
mulae is a traditional practice in naturopathic
and herbal medicine. This has been called
polypharmacy and is looked on unfavorably by
some medical practitioners despite the fact that
many patients are taking more than one phar-
maceutical drug at a time (Colley and Lucas,
1993). For example, one study of elderly peo-
ple living in residential care facilities found that
the average number of prescriptions per resi-
dent was five (Williams et al., 1999). Clinical
experience confirms that polypharmaceutical
prescription of herbs is an effective and safe
means of practice, although it has been poorly
investigated in the Western world. In contrast,
multi-ingredient patent formulae are com-
monly used in Traditional Chinese Medicine
SAFETY OF LARREA TRIDENTATA 183
TABL E 7. PATIENTS REC EIV ING ULT RA -LOW DOSE S OF LA RRE A TR IDE NTATA TINC TU RE
Maximum possible amount Concomitant potentially
Patient Age Gender of
Larrea (mL)ahepatotoxic drugs
S.F. 47 F 22 Acetaminophen
J.R. 39 F 24 None
T.D. 26 M 20 None
L.Y. 55 M 12 None
K.A. 48 F ,5 None
C.W. 47 F ,5 None
K.G. 38 F ,5 Acetaminophen, venlafaxine
M.L. 42 M ,5bNone
aTaken over a period of weeks to months.
bThis patient reported taking significant amounts (more than 100 mL in a 3-month period) of a tincture of
Larrea
tridentata that he prepared himself in combination with two other botanicals. He developed no sign of liver disease
at any point.
and have been the subject of innumerable clin-
ical trials in China. By limiting intake of any
single ingredient in multiherb Chinese or other
formulas, the risk of causing toxic reactions is
lowered. The belief is that the actions of the to-
tality of the plant are synergistic and account
for therapeutic activity despite what would be
insufficient doses (but being small, unlikely to
cause toxicity) of any one constituent in isola-
tion. Synergistic effects may even decrease the
toxicity of plants that are more dangerous in
isolation (Johns, 1990). Although this type of
prescribing might be extremely dangerous us-
ing pharmaceutical compounds, in our experi-
ence, the combination of whole-plant extracts
tends to be safer than the use of single herbs.
One source of information on this practice
can be found in the “approved fixed combina-
tions” of the Commission E monographs
(Bluementhal et al., 1998). Here we find, for
example, a combination of Mentha 3piperita
(peppermint) leaf,
Carum carvi (caraway) seed,
Matricaria recutita (German chamomile) flower
and
Citrus aurantium (bitter orange) peel is ap-
proved for treating patients with dyspepsia by
the official German government committee on
botanical medicine. Each herb has a separate
history of use for this condition, although in
this set combination, at most 40% of each dose
of each single herb is given. Nevertheless, effi-
cacy does not seem to be lost.
The retrospective nature of the study, the
limited number of cases, and lack of a control
group weaken the strength of our findings.
However, no patient for whom
Larrea was pre-
scribed during the study was excluded from
the analysis, thereby reducing selection bias.
The study was also based in everyday practice,
meaning that each patient was taking a variety
of other supplements with few similarities be-
tween them. Additionally, introduction of
Lar-
rea into each patient’s therapy was not ne-
cessarily done while other treatments were
held constant. Although these methodological
weaknesses are generally considered severely
limiting, we believe that in the realm of safety
of typical herbal prescribing they are not as im-
portant. This is because the real-world condi-
tions of the study strengthen the conclusion
that
Larrea as actually prescribed (as compared
to the relatively artificial setting of a single-
agent, controlled, clinical trial) is an acceptable
practice. Thus, while it is difficult to conclude
definitely from this study alone that Larrea is
safe, the preliminary conclusion may be drawn
that when 90% ethanol extracts internally or
Ricinus oil extracts topically of this plant were
used in the doses described herein in combi-
nation with a variety of natural products, no
signs of the liver damage reported elsewhere
were encountered in our practice. These find-
ings also document a lack of general toxicity
and suggest previously reported cases may be
of an idiosyncratic nature, based on the rare
susceptibility of individual patients.
Clearly, prospective studies are needed to
confirm the safety of Larrea. Such studies are
urged to document efficacy and safety for this
useful natural resource.
ACKNOWLEDGMENTS
Elan Botanicals (Sedona, AZ) manufactured
the products involved in this study. Dr. Heron
is the technical director of this company. These
products are available from other sources.
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69113 Camp Polk Road
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E-mail: dryarnell@bendnet.com
SAFETY OF LARREA TRIDENTATA 185
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