5-Hydroxytryptophan: A Clinically-Effective Serotonin Precursor

Abstract

5-Hydroxytryptophan (5-HTP) is the intermediate metabolite of the essential amino acid L-tryptophan (LT) in the biosynthesis of serotonin. Intestinal absorption of 5-HTP does not require the presence of a transport molecule, and is not affected by the presence of other amino acids; therefore it may be taken with meals without reducing its effectiveness. Unlike LT, 5-HTP cannot be shunted into niacin or protein production. Therapeutic use of 5-HTP bypasses the conversion of LT into 5-HTP by the enzyme tryptophan hydroxylase, which is the rate-limiting step in the synthesis of serotonin. 5-HTP is well absorbed from an oral dose, with about 70 percent ending up in the bloodstream. It easily crosses the blood-brain barrier and effectively increases central nervous system (CNS) synthesis of serotonin. In the CNS, serotonin levels have been implicated in the regulation of sleep, depression, anxiety, aggression, appetite, temperature, sexual behaviour, and pain sensation. Therapeutic administration of 5-HTP has been shown to be effective in treating a wide variety of conditions, including depression, fibromyalgia, binge eating associated with obesity, chronic headaches, and insomnia.

Full text

Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998 Page 271
5-Hydroxytryptophan: A Clinically-Effective
Serotonin Precursor
by Timothy C. Birdsall, N.D.
Abstract
5-Hydroxytryptophan (5- HTP) is the intermediate metabolite of the essential
amino acid L-tryptophan (LT) in the biosynthesis of serotonin. Intestinal absorption of
5-HTP does not require the presence of a transport molecule, and is not affected by the
presence of other amino acids; therefore it may be taken with meals without reducing
its effectiveness. Unlike LT, 5-HTP cannot be shunted into niacin or protein production.
Therapeutic use of 5-HTP bypasses the conversion of LT into 5-HTP by the enzyme
tryptophan hydroxylase, which is the rate-limiting step in the synthesis of serotonin. 5-
HTP is well absorbed from an oral dose, with about 70 percent ending up in the
bloodstream. It easily crosses the blood-brain barrier and effectively increases central
nervous system (CNS) synthesis of serotonin. In the CNS, serotonin levels have been
implicated in the regulation of sleep, depression, anxiety, aggression, appetite,
temperature, sexual behavior, and pain sensation. Therapeutic administration of 5-HTP
has been shown to be effective in treating a wide variety of conditions, including
depression, fibromyalgia, insomnia, binge eating associated with obesity, chronic
headaches, and insomnia.
(
Altern Med Rev
1998;3(4):271-280)
Introduction
5-Hydroxytryptophan (5-HTP) (see Figure 1) is an aromatic amino acid naturally pro-
duced by the body from the essential amino acid L-tryptophan (LT). Produced commercially by
extraction from the seeds of the African plant, Griffonia simplicifolia, 5-HTP has been used
clinically for over 30 years. The clinical efficacy of 5-HTP is due to its ability to increase
production of serotonin in the brain.
Metabolism of Tryptophan and Serotonin
Serotonin (5-hydroxytryptamine), dopamine, and norepinephrine are the three main
“monoamine” neurotransmitters, each produced endogenously from one specific amino acid.
Tryptophan is converted into serotonin, while dopamine and norepinephrine are made from
tyrosine. In the central nervous system (CNS), serotonin has been implicated in regulation of
sleep, depression, anxiety, aggression, appetite, temperature, sexual behavior, and pain sensa-
tion.
Timothy C. Birdsall, N.D.
Correspondence address: e-mail: 73541.2166@compuserve.com or altmedrev@thorne.com
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Page 272 Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998
While other cells outside the brain,
such as blood platelets and some enterocytes,
make and/or use serotonin, all serotonin used
by brain cells must be made within the neu-
rons, since serotonin cannot cross the blood-
brain barrier. Therefore, the synthesis of sero-
tonin is heavily dependent upon the availabil-
ity of LT within the CNS. The production and
subsequent transport of LT from the blood-
stream into the CNS can be compromised by
several factors:
1) Stress, elevated cortisol levels, vi-
tamin B6 deficiency, and even high dosages
(above 2,000 mg) of LT, which all stimulate
the conversion of LT to kynurenine, lowering
serum LT levels.
1-3
(See Figure 2)
2) Elevated serum levels of kynurenine
inhibit transport of LT into the CNS, and re-
duce CNS serotonin levels.
4
3) Transport of LT across the blood-
brain barrier requires binding to a transport
molecule, which LT shares with five other
amino acids (tyrosine, phenylalanine, valine,
leucine and isoleucine). Since LT is present in
foods in relatively small amounts in
comparison to these other amino acids, as little
as one percent of dietary LT
may be transported into the
CNS.
4) LT is used by the
body for other metabolic
purposes in addition to se-
rotonin production, includ-
ing protein synthesis and the
creation of niacin.
Biochemistry and
Metabolism of 5-HTP
5- HTP is the interme-
diate metabolite of LT in the
production of serotonin (see
Figure 2). Therapeutic use
of 5-HTP bypasses the con-
version of LT into 5-HTP by
the enzyme tryptophan hy-
droxylase, which is the rate-limiting step in
the synthesis of serotonin. Tryptophan hy-
droxylase can be inhibited by numerous fac-
tors, including stress, insulin resistance, vita-
min B6 deficiency, and insufficient magne-
sium. In addition, these same factors can in-
crease the conversion of LT to kynurenine via
tryptophan 2,3-dioxygenase, making LT un-
available for serotonin production.
5-HTP is well absorbed from an oral
dose, with about 70 percent ending up in the
bloodstream.
5,6
Absorption of 5-HTP is not af-
fected by the presence of other amino acids;
therefore, it may be taken with meals without
reducing its effectiveness. Unlike LT, 5-HTP
cannot be shunted into niacin or protein pro-
duction.
Serotonin levels in the brain are highly
dependent on levels of 5-HTP and LT in the
central nervous system (CNS). 5-HTP easily
crosses the blood-brain barrier, not requiring
the presence of a transport molecule. LT, on
the other hand, requires use of a transport
molecule to gain access to the CNS. Since LT
shares this transport molecule with several
other amino acids, the presence of these
5-Hydroxytryptophan
L-tryptophan
B6
Serotonin
other
metabolites
SAM
Melatonin
Tryptophan
5-monooxygenase
N-Formylkynurenine
Kynurenine
3-Hydroxykynurenine
B6
3- Hydroxyanthranilic acid
carboxymuconic aldehyde intermediate
B6
Xanthurenic acid
Picolinic acid Quinolinic acid
Nicotinic acid (Niacin)
Figure 1. Tryptophan metabolism
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Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998 Page 273
5-Hydroxytryptophan
competing amino acids can inhibit LT transport
into the brain.
Mechanisms of Action
5-HTP acts primarily by increasing
levels of serotonin within the central nervous
system. Other neurotransmitters and CNS
chemicals, such as melatonin, dopamine, nor-
epinephrine, and beta-endorphin have also
been shown to increase following oral admin-
istration of 5-HTP.
7-10
This ability to increase
not only serotonin levels in the brain, but also
dopamine and norepinephrine, allows 5-HTP
to produce some significant and unique effects
on brain chemistry and on serotonin-related
conditions which other substances, including
LT, cannot duplicate.
Clinical Studies Using 5-HTP
Depression: Much of the published re-
search on 5-HTP has to do with its use in the
treatment of depression. Since the early 1970s,
at least 15 studies have evaluated the clinical
effects of 5-HTP on depression .
11-25
These are
summarized in Table 1. Taken together, these
studies examined a total of 511 patients with
different types of depression. Of these 511
subjects, 285 (56%) showed significant im-
provement while taking 5-HTP.
In addition, biochemical studies show
5-HTP is closely involved in depressive
disorders. In a study employing positron-
emission tomography (PET) scanning, eight
healthy volunteers and six people diagnosed
with major depression received infusions of
radiolabelled 5-HTP. The researchers found
significantly less 5-HTP crossed the blood-
brain barrier into the brains of the depressed
subjects than into the brains of the normal
controls. The authors suggested the transport
of 5-HTP across the blood-brain barrier may
be compromised in major depression,
26
which
might make the brain dependent on LT to 5-
HTP conversion in the brain.
Some concern has arisen regarding
whether 5-HTP should be used only in con-
junction with a peripheral decarboxylase in-
hibitor (PDI) such as carbidopa. The argument
is essentially that without a PDI, 5-HTP will
be converted into serotonin in the peripheral
circulation, negating any potential CNS bene-
fit from 5-HTP.
13,22-24
However, this argument
ignores scores of clinical studies in which 5-
HTP was given alone and in which significant
clinical benefit was seen, with no significant
adverse effects.
The first large clinical trial using 5-
HTP in depression was conducted by Sano in
1972. Using an open trial design, a total of
107 patients with endogenous unipolar or bi-
polar depression were given daily oral dosages
of 5-HTP from 50 to 300 mg. Significant im-
provement was observed in 74 of the patients
(69%), and no significant side effects were re-
ported. The response rate in most of these pa-
tients was quite rapid (less than two weeks).
11
The issue of speed of response was
subsequently addressed in a study of 59 pa-
tients with eight different types of depression.
5-HTP was administered orally in dosages
from 150 to 300 mg daily for a period of three
weeks. Thirteen patients (22%) were markedly
improved, and another 27 patients (45.8%)
showed moderate improvement. Of these 40
patients who improved, 20 (50%) began to
show improvement within three days, and 32
patients (80%) improved within two weeks of
beginning treatment with 5-HTP.
15
In contrast
to many conventional antidepressants which
may take 4 weeks or longer to achieve thera-
peutic response in most patients, those taking
5-HTP appear to have a significantly more
rapid response.
Japanese researchers administered 5-
HTP to 24 patients hospitalized for depression.
After two weeks of treatment, a “marked
amelioration of depressive symptoms” was
observed in seven patients diagnosed with
unipolar depression. The administration of
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Page 274 Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998
Table 1. Clinical trials of 5-HTP use in depression
Reference Number Diagnosis Study Design 5-HTP Duration of Results
of Patients Dosage treatment
(mg/day) (days)
Sano
11
107 Endogenous depression Open Trial 50-300 7-35 74/107 markedly improved
Fujiwara
12
20 Endogenous depression Open Trial 50-200 7-28 10/20 markedly improved
Matussek
13
23 Unipolar depression (13); Open Trial 100-300 4-20 7/23 markedly improved
bipolar depression (1);
involutional depression (8);
schizoaffective depression (1)
Takahashi
14
24 Unipolar depression (20); Open Trial 300 14 7/20 in the unipolar group
involutional depression (2); markedly improved
neurotic depression (1);
psychotic depression (1)
Nakajima
15
59 Mixed group; 8 different Open Trial 150-300 21+ 13/59 markedly improved;
types of depression 27/59 moderately improved
van Hiele
16
99 Endogenous depression (44); Open Trial 50-600 a 14+ 37/68 in the endogenous
depression with endogenous group and 6/31 in the personal
features (24); personal group markedly improved
depression (31)
Kaneko
17
18 Endogenous depression Open Trial 150-300 10-28 10/18 markedly improved
van Praag
18
5 Endogenous depression Double-blind; 200-3,000 21 3/5 markedly improved
(unipolar and bipolar) 5-HTP vs. placebo
Brodie
19
7 Psychotic depression (6); Double-blind; 250-3,250 1-15 1/7 moderately improved
schizoaffective psychosis (1) 5-HTP vs. placebo
Barlet
20
25 Melancholia (4); involutional Double-blind; 200-800 10-240 19/25 improved
depression (7); reactive 5-HTP vs. placebo
depression (8); neurotic
depression (6)
Lopez
21
14 Endogenous depression Double-blind; 50-300 15-20 12/15 markedly improved
5-HTP vs. nialamide
van Praag
22
20 Endogenous depression Double-blind; 200
a
21 11/20 markedly improved; 5-HTP
(unipolar and bipolar) 5-HTP vs. clomipramine and clomipramine equally effective
vs. placebo
van Praag
23
15 Endogenous depression Double-blind; 200
a
28 8/15 markedly improved; 5-HTP
(unipolar and bipolar) 5-HTP vs. tryptophan more effective than tryptophan
vs. placebo or plaecbo
Mendlewicz
24
39 Bipolar (24); unipolar(15) Double-blind; 300
a
32 13/21 responded to 5-HTP alone
5-HTP vs. 5-HTP
+deprenyl vs. placebo
Poldinger
25
36 Endogenous depression (10); Double blind; 300 42 27/36 improved
reactive depression (16); 5-HTP vs. fluvoxamine
situational depression (9);
involutional depression (1);
Total 511 285/511 improved
Total — Double 161 94/161 improved
blind studies
only
Adapted from van Praag and Lemus.
7
a
5-HTP was given in combination with a peripheral decarboxylase inhibitor.
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Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998 Page 275
5-Hydroxytryptophan
5-HTP was also associated with a 30 percent
increase in the levels of 5-hydroxyindolacetic
acid, the primary metabolite of serotonin, in
the patients’ cerebrospinal fluid. This
suggested the exogenous 5-HTP was being
converted to serotonin within the CNS.
14
5-HTP vs. Conventional Anti-depres-
sants: The current conventional therapies of
choice for depression are the selective seroto-
nin reuptake inhibitors (SSRIs). A 1991 Swiss
study evaluated 5-HTP in comparison to an
SSRI drug in a double-blind, multicenter study
design. A total of 36 subjects, all of whom were
diagnosed with some form of depression, re-
ceived either 100 mg of 5-HTP three times per
day, or 150 mg of fluvoxamine (an SSRI) three
times daily. The subjects were evaluated at 0,
2, 4, and 6 weeks, using four evaluation tools:
the Hamilton Rating Scale for Depression
(HRSD), a standard depression rating scale; a
patient-performed self-assessment; the
investigator’s assessment of severity; and a
global clinical impression.
25
Both treatment groups showed signifi-
cant and nearly equal reductions in depression
beginning at week two and continuing through
week six. After four weeks, 15 of the 36 pa-
tients treated with 5-HTP, and 18 of the 33
patients treated with fluvoxamine had im-
proved by at least 50 percent, according to the
HRSD scores. By week six, the two groups
had about equal numbers showing 50 percent
improvement. When the numbers were totaled
at the end of the study, the researchers found
the mean percentage improvement from
baseline to the final assessment was slightly
greater for patients treated with 5-HTP. The
number of treatment failures was higher in the
fluvoxamine group (5/29, 17%) than in the 5-
HTP group (2/34, 6%), although neither of
these differences were statistically significant.
All four evaluation tools yielded similar re-
sults.
The study also looked at the incidence
of adverse effects from both treatments, which
were found to be rare and generally mild,
usually occurring during the first few days of
treatment and then disappearing. Overall, 5-
HTP appeared to be slightly better tolerated
than fluvoxamine, although the results did not
reach the level of statistical significance.
Tolerance was assessed as being “good to very
good” in 34/36 patients receiving 5-HTP
(94.5%), compared to 28/33 in the
fluvoxamine group (84.8%).
25
5-HTP has also been compared in a few
studies with conventional tricyclic antidepres-
sants (chloripramine and imipramine) - the
most effective drugs for treating depression
until the development of the SSRIs. The stud-
ies found 5-HTP to be at least as effective as
these drugs in treating severe depression, while
displaying fewer side effects. In severe cases,
5-HTP dosages as high as 1200 mg daily were
used.
22,27-29
Fibromyalgia: Primary fibromyalgia
syndrome is characterized by general musculo-
skeletal aching, multiple tender points, fatigue,
morning stiffness, and sleep disturbances.
Fibromyalgia patients have been found to have
low serotonin
30,31
and tryptophan
32,33
levels,
and some studies have shown symptomatic
improvement with the use of tricyclic and
SSRI antidepressants.
34,35
These findings sug-
gest 5-HTP might be useful in the treatment
of fibromyalgia, and three clinical trials have
demonstrated significant improvement in
symptoms, including pain, morning stiffness,
anxiety, and fatigue.
36-38
Caruso et al conducted a double-blind,
placebo-controlled study in 50 fibromyalgia
patients, administering 100 mg of 5-HTP three
times daily for a period of 30 days. Signifi-
cant improvements were seen in number of
tender points (p<0.001), subjective pain sever-
ity (p<0.001), morning stiffness (p=0.017),
sleep patterns (p<0.001), anxiety ratings
(p<0.001), and fatigue ratings (p=0.003). The
incidence of side effects in the 5-HTP group
was low (6/25 patients), and no significant
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Page 276 Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998
laboratory abnormalities were reported during
the study.
38
In a longer-term study, a total of 50
patients diagnosed with primary fibromyalgia
syndrome were given 100 mg 5-HTP three
times per day for 90 days in an open study.
Patients were assessed at the beginning of the
study and after 15, 30, 60, and 90 days of treat-
ment. The clinical variables evaluated in-
cluded: total number of tender points, pain
intensity, sleep quality, morning stiffness, anxi-
ety, and fatigue. All of these measures showed
significant improvement throughout the length
of the study (p<0.001). A total of 15 patients
(30%) reported side effects from the 5-HTP,
but in only one case were they severe enough
for the patient to be withdrawn from the
study.
37
In a randomized, placebo-controlled
study of 200 fibromyalgia patients who were
also migraine sufferers, 5-HTP (400 mg/day)
was compared to a tricyclic drug (amitrip-
tyline) and a monoamine oxidase inhibitor
(MAOI) drug (pargilyne or phenelzine). The
combination of 5-HTP (200 mg/day) with an
MAOI was also evaluated. Patients were
treated for a total of 12 months and kept a daily
pain diary by means of a visual analogic scale.
At the end of the twelve-month trial period,
all treatment regimens showed significant im-
provement over placebo (p<0.0001), although
the combination of 5-HTP with the MAOI was
the most effective. 5-HTP alone was as effec-
tive as the tricyclic or MAOI drugs. No pa-
tients withdrew from the study due to side ef-
fects; eight percent of the patients taking 5-
HTP alone reported some degree of stomach
upset.
36
Obesity: During dieting, serum
tryptophan levels and CNS serotonin levels
drop dramatically.
39-41
These low serotonin
levels in obese patients have been associated
with carbohydrate cravings and resultant binge
eating. It has been theorized that 5-HTP can
help prevent this dieting-associated decline in
serotonin, thus enhancing weight loss. Three
clinical trials in obese patients have
demonstrated decreased food intake and
subsequent weight loss with 5-HTP
supplementation.
42-44
Using a placebo-controlled, double-
blind protocol, researchers at the University
of Rome evaluated the effects of 5-HTP (300
mg three times daily) on the eating habits and
weight loss of 20 obese female patients. All
patients had a body mass index between 30
and 40, and were determined to consume an
excess of food daily, based on calculated en-
ergy needs. The twelve-week study period was
divided into two six-week sections. During the
first six weeks, the patients took either 5-HTP
or placebo, but no dietary restrictions were
placed on them. In the second six-week pe-
riod, the patients were placed on a 1200 calo-
rie per day diet, while continuing to take ei-
ther the 5-HTP or placebo. Subjects compiled
detailed 3-day food diaries once every two
weeks.
42
Those in the placebo group did not ex-
perience significant weight loss in either of the
two periods (94.3 ± 5.6 kg vs. 93.2 ± 5.3 kg ),
while the subjects in the 5-HTP group showed
significant weight loss in both the first period
(99.7 ± 5.9 kg vs. 98.0 ± 5.0 kg, p<0.03) and
the second period (98.0 ± 5.0 vs. 94.7 ± 5.1
kg, p<0.02). The placebo group also did not
show significant change in their calorie intake,
even in the second period when instructed to
reduce food intake, while the 5-HTP group had
a significant spontaneous dietary intake reduc-
tion during the first period, from 3220 calo-
ries/day to 1879 calories/day (p<0.001), with
carbohydrate intake falling by 50 percent.
During the second period, the calorie intake
of the 5-HTP group decreased further, to 1268
calories/day (p<0.01), with further reductions
in carbohydrates. The researchers interpreted
these findings as supporting the theory that
5-HTP decreased carbohydrate cravings and
binge eating, even in the absence of a struc-
tured diet.
42
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Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998 Page 277
5-Hydroxytryptophan
At this high dosage of 5-HTP (900 mg/
day), about 80 percent of the subjects initially
reported experiencing some nausea. However,
this side effect was not severe enough to cause
any of the subjects to drop out of the study,
and was less frequent during the second six-
week period, suggesting that this symptom
may be a transitory effect of 5-HTP
administration.
42
Chronic Headaches: Chronic head-
aches, especially migraines, are considered by
some researchers to be the result of low sero-
tonin levels, probably as the result of increased
breakdown of serotonin by the enzyme
monoamine oxidase.
45,46
Low serotonin levels
are thought to lower pain thresholds in chronic
headache sufferers, allowing other headache
triggers to more easily “set off” a headache.
5-HTP has been used successfully in
the prevention of chronic headaches of vari-
ous types, including migraine, tension head-
aches, and juvenile headaches.
36,47-52
In a large
study of 124 subjects, the ability of 5-HTP to
prevent migraines was compared to
methysergide, one of the most commonly used
migraine drugs. At a dosage of 600 mg daily
for six months, 5-HTP totally prevented or
substantially decreased the number of migraine
attacks in 75 percent of the subjects. However,
this difference was not determined to be sta-
tistically significant.
49
In a study of 48 elemen-
tary and junior high school students, 5-HTP
(4.5 mg/kg/day) produced a 70 percent de-
crease in headache frequency, compared to an
11 percent decrease in the placebo group.
48
Insomnia: 5-HTP has been shown to
be beneficial in treating insomnia, especially
in improving sleep quality by increasing REM
sleep.
53-55
Eight normal subjects were
monitored to determine the effect of 5-HTP
on rapid eye movement (REM) sleep. A total
of 600 mg 5-HTP was administered to the
subjects in the following manner: 200 mg at
9:15 pm, followed by 400 mg at 11:15 pm. A
significant increase in the amount of REM
sleep was observed while the subjects were
taking 5-HTP (118 ± 14 mins vs. 98 ± 11 mins,
p<0.005). A smaller study using a 200 mg dose
also showed increases in REM sleep, but to a
lesser degree.
55
The smaller dose is probably
preferable, since, according to anecdotal
reports, higher doses may have a tendency to
cause very vivid dreams or nightmares.
Dosage
Initial dosage for 5-HTP is usually 50
mg three times per day with meals. If the clini-
cal response is inadequate after two weeks,
dosage may be increased to 100 mg three times
per day. For insomnia, the dosage is usually
100-300 mg before bedtime. Because some pa-
tients may experience mild nausea when initi-
ating treatment with 5-HTP, it is advisable to
begin with 50 mg doses and titrate upward.
Drug-Nutrient Interactions
Although no specific reports have been
published, it is possible that 5-HTP, when
taken in combination with either a selective
serotonin reuptake inhibitor (SSRI) antidepres-
sant such as fluoxetine (Prozac), paroxetine
(Paxil), sertraline (Zoloft), or fluvoxamine
(Luvox), or an MAOI antidepressant such as
phenelzine (Nardil) or tranylcypromine
(Parnate) may cause a condition known as sero-
tonin syndrome.
56
This syndrome has been
reported in patients taking LT at doses above
1200 mg/day along with MAOIs, but was not
identified in a 12-month study with 5-HTP
(200 mg/day) taken in conjunction with an
MAOI drug.
36
Serotonin syndrome is characterized
by agitation, confusion, delirium, tachycardia,
diaphoresis, and blood pressure fluctuations.
Should serotonin syndrome be suspected, 5-
HTP and any other precipitating drug (SSRI
or MAOI) should be discontinued immedi-
ately. Because of the possibility of serotonin
syndrome, 5-HTP should probably not be used
in patients currently being treated with either
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Page 278 Alternative Medicine Review
◆ Volume 3, Number 4 ◆ 1998
an SSRI or MAOI antidepressant. If it is used
in conjunction with either of these prescrip-
tion drugs, e.g. short-term dual therapy while
changing over from an SSRI to 5-HTP, the
practitioner and patient should be aware of the
potential symptoms of this condition.
Contraindications
One additional concern regarding 5-
HTP is the possibility of an eosinophilia-my-
algia syndrome (EMS) similar to the illness
linked to contaminated LT. The contamination
identified in certain batches of LT has been
related to production methods using bacterial
fermentation and subsequent inadequate fil-
tration. This is unlikely to occur with 5-HTP,
since it is produced by extraction from plant
sources. Two cases of EMS-like symptoms
have been described in patients taking 5-HTP.
One case reported in 1980 involved the use of
very high doses (1400 mg daily).
57
Because
contamination of LT was not identified as a
factor in EMS until 1990, the product con-
sumed by this patient was not tested for con-
tamination. The second case involved a mother
and two children who were confirmed to have
taken contaminated 5-HTP.
58
Because of the possibility of seroto-
nin syndrome (see above), 5-HTP should be
used with caution in patients currently being
treated or who have recently been treated with
either an SSRI or an MAOI antidepressant.
There are no adequate, well-controlled
studies on the use of 5-HTP in pregnancy,
therefore, it should not be used while preg-
nant.
Side Effects
Some patients may initially experience
mild nausea when taking 5-HTP. This effect
is usually transitory, and is best dealt with by
initiating therapy at low doses (50 mg three
times daily) and increasing the dosage gradu-
ally if necessary.
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