Effectiveness and Safety of Ginger in the Treatment of Pregnancy-Induced Nausea and Vomiting
Conventional antiemetics are burdened with the potential of teratogenic effects during the critical embryogenic period of pregnancy. Thus, a safe and effective medication would be a welcome addition to the therapeutic repertoire. This systematic review was aimed at assessing the evidence for or against the efficacy and safety of ginger (Zingiber officinale) therapy for nausea and vomiting during pregnancy. Systematic literature searches were conducted in 3 computerized databases (MEDLINE, EMBASE, and Cochrane Library), and the reference lists of all papers located were checked for further relevant publications. For the evaluation of efficacy, only double-blind, randomized controlled trials (RCTs) were included. All retrieved clinical data, including uncontrolled trials, case reports, observational studies, and RCTs, were included in the review of safety. Six double-blind RCTs with a total of 675 participants and a prospective observational cohort study (n = 187) met all inclusion criteria. The methodological quality of 4 of 5 RCTs was high. Four of the 6 RCTs (n = 246) showed superiority of ginger over placebo; the other 2 RCTs (n = 429) indicated that ginger was as effective as the reference drug (vitamin B6) in relieving the severity of nausea and vomiting episodes. The observational study retrieved and RCTs (including follow-up periods) showed the absence of significant side effects or adverse effects on pregnancy outcomes. There were no spontaneous or case reports of adverse events during ginger treatment in pregnancy. Ginger may be an effective treatment for nausea and vomiting in pregnancy. However, more observational studies, with a larger sample size, are needed to confirm the encouraging preliminary data on ginger safety. I.
Effectiveness and Safety of Ginger in the Treatment
of Pregnancy-Induced Nausea and Vomiting
, Raffaele Capasso,
, Gabriella Aviello,
Max H. Pittler,
, and Angelo A. Izzo,
OBJECTIVE: Conventional antiemetics are burdened with
the potential of teratogenic effects during the critical em-
bryogenic period of pregnancy. Thus, a safe and effective
medication would be a welcome addition to the therapeutic
repertoire. This systematic review was aimed at assessing
the evidence for or against the efﬁcacy and safety of ginger
(Zingiber ofﬁcinale) therapy for nausea and vomiting dur-
DATA SOURCES: Systematic literature searches were con-
ducted in 3 computerized databases (MEDLINE, EMBASE,
and Cochrane Library), and the reference lists of all papers
located were checked for further relevant publications.
METHODS OF STUDY SELECTION: For the evaluation of efﬁ-
cacy, only double-blind, randomized controlled trials
(RCTs) were included. All retrieved clinical data, includ-
ing uncontrolled trials, case reports, observational studies,
and RCTs, were included in the review of safety.
TABULATION, INTEGRATION, AND RESULTS: Six double-blind
RCTs with a total of 675 participants and a prospective
observational cohort study (n ⴝ 187) met all inclusion
criteria. The methodological quality of 4 of 5 RCTs was
high. Four of the 6 RCTs (n ⴝ 246) showed superiority of
ginger over placebo; the other 2 RCTs (n ⴝ 429) indicated
that ginger was as effective as the reference drug (vitamin
B6) in relieving the severity of nausea and vomiting epi-
sodes. The observational study retrieved and RCTs (in-
cluding follow-up periods) showed the absence of signiﬁ-
cant side effects or adverse effects on pregnancy outcomes.
There were no spontaneous or case reports of adverse
events during ginger treatment in pregnancy.
CONCLUSION: Ginger may be an effective treatment for
nausea and vomiting in pregnancy. However, more obser-
vational studies, with a larger sample size, are needed to
conﬁrm the encouraging preliminary data on ginger safety
(Obstet Gynecol 2005;105:849–56. © 2005 by The Amer-
ican College of Obstetricians and Gynecologists.)
LEVEL OF EVIDENCE: I
Nausea and vomiting (commonly referred to as morning
sickness) are very common symptoms in pregnancy,
affecting 70 – 85% and 40–50% of pregnant women,
It has been estimated that the ﬁnancial
burden of morning sickness on the American health
system is more than 130 million dollars per year.
Usually morning sickness begins between the ﬁrst and
second missed menstrual period and may last until the end
of the third month of pregnancy. However, approximately
20% of women experience nausea and vomiting for a
longer period of time, and 2% of this group suffers until the
end of the pregnancy. Moreover, a small number (0.3–3%)
of all pregnant women experience a more severe form of
morning sickness, namely hyperemesis gravidarum.
Many medications are currently available for the treat-
ment of morning sickness.
However, concerns about
the potential teratogenic effects of drugs administered
during the critical embryogenic period of pregnancy
drastically limit their use. Consequently, many pregnant
women use complementary and alternative therapies.
These include vitamins, herbal products, homeopathic
preparation, acupressure, and acupuncture.
literature survey reports that the most commonly used
natural drugs for the treatment of morning sickness are
ginger, chamomile, peppermint, and raspberry leaf.
Among these, only ginger has been evaluated in con-
trolled trials for the treatment of morning sickness.
Ginger, a rhizome of Zingiber ofﬁcinale Roscoe (Fam.
Zingiberaceae), has been widely used as a spice to enhance
the ﬂavor of food and beverage and for medical pur-
poses, particularly to treat ailments such stomachache,
diarrhea, and nausea.
Ginger is among the 20 top-
selling herbal supplements in the United States, and its
retail sales in the mainstream U.S. market in 2001
amounted to 1.2 million dollars.
German and Euro-
pean monographs are available, and both list nausea/
vomiting as indications. Moreover, in 1997 the U.S.
Pharmacopoeia approved ginger and powdered ginger
monographs for inclusion in the National Formulary.
From the Department of Experimental Pharmacology, University of Naples Fed-
erico II, Naples, Italy; and Complementary Medicine, Peninsula Medical School,
Universities of Exeter and Plymouth, Exeter, United Kingdom.
VOL. 105, NO. 4, APRIL 2005
849© 2005 by The American College of Obstetricians and Gynecologists. 0029-7844/05/$30.00
Published by Lippincott Williams & Wilkins. doi:10.1097/01.AOG.0000154890.47642.23
Given the widespread use of ginger as an antiemetic drug,
we systematically assessed the efﬁcacy and safety of this herbal
product in the treatment of nausea and vomiting in pregnancy.
Literature searches were performed to identify all clinical
reports regarding the efﬁcacy and safety of ginger in
pregnancy. Three electronic databases, MEDLINE,
EMBASE, and Cochrane Library, were searched (all
from their respective inceptions to June 2004) using the
search terms “ginger” and “Zingiber ofﬁcinale.” No lan-
guage restrictions were imposed. Citations and bibliog-
raphies of all retrieved papers were reviewed for further
relevant publications not found in the electronic
searches. Additionally, several manufacturers of ginger-
containing preparations were asked to contribute pub-
lished or unpublished material, and web sites devoted to
providing information for pregnant women were visited.
For the evaluation of efﬁcacy, only double-blind, ran-
domized controlled trials (RCTs) of the oral administra-
tion of a monopreparation of ginger for the treatment of
the symptoms of pregnancy-related nausea and vomiting
(morning sickness and hyperemesis gravidarum) were in-
cluded. All retrieved clinical data, including uncontrolled
trials, case reports, and observational studies, were in-
cluded in the review of safety. For papers not reporting
enough information, the authors were contacted to provide
additional data. The methodological quality of each study
was assessed using the scoring system developed by Jadad
and colleagues (Box: “Jadad Score: Instrument Used to
Assess Methodological Quality of Clinical Trials”).
reviewers independently performed the screening of stud-
ies, selection, validation, data extraction, and the assess-
ment of methodological quality. Disagreements about the
assessment of data were resolved by discussion, and con-
sensus was reached in all cases. A meta-analysis was con-
sidered but proved to be not feasible. Because of the differ-
ent measures used to assess the outcomes and because of
the different control groups in the trials, a clinically mean-
ingful pooling of the data was not possible.
The searches identiﬁed 33 potentially relevant tri-
but only 6 double-blind RCTs
aforementioned inclusion criteria and were included in
this systematic review. The ﬂow chart provides an over-
view of all included and excluded trials (Fig. 1). The
assessment of their methodological quality revealed a
maximal score for 5 of 6 studies. Four RCTs
compared the efﬁcacy of ginger to placebo, whereas 2
compared the efﬁcacy of ginger to vitamin B6
(used as a reference compound). Key data are summa-
Fig. 1. Flowchart of studies included and excluded. RCTs,
randomized controlled trials.
Borrelli. Ginger and Pregnancy. Obstet Gynecol 2005.
Jadad Score: Instrument Used to Assess
Methodological Quality of Clinical Trials
Each “yes” scores 1 point; each “no” 0 points:
x Study described as randomized (this includes the
use of words such as random, randomly, and ran-
x Study described as double-blind?
x Description of withdrawals and dropouts?
x Method to generate the sequence of randomiza-
tion described and appropriate (table of random
numbers, computer generated, etc.)?
x Method of double-blinding described and appro-
priate (identical placebo, active placebo, dummy,
Deduct 1 point if:
x Method to generate the sequence of randomiza-
tion described and inappropriate (patients were
allocated alternately, or according to their date of
birth, hospital number, etc.)?
x Method of double-blinding described and inap-
propriate (comparison of tablet versus injection
with no double dummy, etc.)?
850 Borrelli et al Ginger and Pregnancy OBSTETRICS & GYNECOLOGY
rized in Table 1, while the main results are described
The ﬁrst double-blind, crossover RCT included 30
pregnant women who needed hospitalization for hy-
peremesis gravidarum before the 20th week of gesta-
Twenty-seven woman completed the trial. Pa
tients received either ginger (250 mg) or placebo (lactose,
250 mg) 4 times a day for 4 days; the washout period was
2 days. No indication on the source of the ginger pow-
dered root was reported. Other antiemetic medications
Table 1. Clinical Trials Reporting the Effectiveness of Ginger in Treatment of Pregnancy-Related Nausea and Vomiting
Study JS Design
Measures Main Results
⬍ 20 250 mg 4
Placebo 4 d Severity and relief
of nausea and
change in body
Ginger was better
than placebo in
⬍ 17 250 mg 4
Placebo 4 d Severity of nausea
scale and Likert
scale); number of
occurrence of side
Ginger was more
severity of nausea
and vomiting; no
adverse effect was
⬍ 12 250 mg 4
Placebo 2 wk Duration and
severity of nausea
and vomiting (10-
Ginger was more
⬍ 17 500 mg 3
(10 mg; 3
3 d Severity of nausea
scale), number of
nausea score and
were observed in
⬍ 20 125 mg
4 d Nausea, vomiting,
occurrence of side
Ginger was more
and retching; no
350 mg 3
(25 mg; 3
3 wk Nausea, retching,
and vomiting at
days 7, 14, 21
in health status
Ginger was as
vitamin B6 in
dry retching, and
JS, Jadad Score; NPS/NPE, number of pregnancies at the start of trial/number of pregnancies at the end of trial; LT, length of treatment; G, patients
in the ginger group; C, patients in the control group; MOS, Medical Outcomes Study.
851VOL. 105, NO. 4, APRIL 2005 Borrelli et al Ginger and Pregnancy
were withdrawn. Outcomes included degree of nausea
and vomiting, change in body weight, adverse effects on
pregnancy, and pregnancy outcomes. The degree of nau-
sea and vomiting was evaluated by using 2 relief and
severity scoring systems. The relief score aimed to evaluate
the efﬁcacy of ginger, whereas the severity score was used
to exclude a potential beneﬁcial effect of ginger to the
second period of treatment (placebo). The results showed
that ginger was better than placebo in diminishing or elim-
inating the symptoms of hyperemesis gravidarum.
Vutyavanich et al
evaluated the effectiveness of
ginger on pregnancy-induced nausea and vomiting in a
double-masked, placebo-controlled RCT. Sixty-seven
(70 at the beginning of the trial) women before the 17th
week of gestation who manifested nausea (with or with-
out vomiting) and did not take any other medication in
the week before the study were evaluated. Subjects re-
ceived either 250 mg ginger or placebo 4 times daily for
4 days. Ginger preparations were obtained from fresh
ginger root, which was chopped into small pieces, baked
at 60°C for 24 hours, and then ground into powder.
Outcomes included change in nausea symptoms and
number of vomiting episodes. Occurrence of side effects
and adverse effects on pregnancy outcomes, such as
abortion, preterm birth, congenital anomaly, perinatal
death, and mode of delivery, were also taken into ac-
count. The degree of nausea and the number of vomiting
episodes were recorded 24 hours before treatment, as
well as twice daily (nausea) or one time daily (vomiting)
each subsequent day of treatment. To avoid the subjec-
tivity of nausea symptoms, 2 independent measurement
scales, a visual analogue scale (objective) and a 5-item
Likert scale (subjective), were used to quantify the changes
in severity. The results showed a signiﬁcantly (time-depen-
dent) greater reduction in nausea score and in the number
of vomiting episodes in the ginger group than in the placebo
group. Reductions of nausea score and vomiting epi-
sodes were signiﬁcant compared with placebo only on
day 3 and day 2 of treatment, respectively.
The third double-blind RCT included 23 pregnant
women (26 at the beginning of the trial), in the ﬁrst
trimester of pregnancy, with nausea and with or without
Patients received either a tablespoon of
syrup containing 250 mg ginger or placebo syrup 4 times
daily for 2 weeks. Ginger rhizome juice was obtained via
a carbon dioxide supercritical extract of dried ginger
rhizome. The level of nausea and number of vomiting
episodes were recorded daily in a diary and quantiﬁed
on a numerical scale of 1 to 10. The effect of ginger on
pregnancy weight, but not on pregnancy outcomes, was
also analyzed. After 9 days, treatment, nausea levels
were reduced in 77% and 20% of patients in the ginger
and placebo groups, respectively. Moreover, 67% of
women in the ginger group and 20% of women in the
placebo group (who were vomiting daily at the begin-
ning of the treatment) stopped vomiting by day 6.
One hundred thirty-eight (128 completed the trial)
pregnant women before 17 weeks of gestation
enrolled in the fourth double-blind RCT. Patients re-
quested antiemetics for the nausea symptoms and did
not take any other medication in the week before the
study. Subjects received either a 500-mg capsule of gin-
ger or 10-mg capsule of vitamin B6 orally 3 times daily.
Ginger preparations were obtained from fresh middle-
aged ginger root, which was chopped into small pieces,
dried in sunlight, and ground into powder. Outcomes
included change in nausea symptoms and number of
vomiting episodes and occurrence of adverse effects
(drowsiness, palpitations, heartburn, and mouth dry-
ness). Effects of ginger on pregnancy outcomes were not
analyzed. The degree of nausea (using the visual ana-
logue scale) and the number of vomiting episodes were
measured 24 hours before treatment, as well as 3 times
daily on each subsequent day of treatment. Both ginger
and vitamin B6 signiﬁcantly reduced the degree of nau-
sea and the number of vomiting episodes. The reduc-
tions of nausea score and nausea episodes were signiﬁ-
cant after a 1-day treatment.
A double-blind, placebo-controlled RCT evaluated
the effectiveness of a ginger extract (EV.EXT35) on 120
women with morning sickness before 17th week of ges-
Subjects received either 125 mg of ginger extract
(equivalent to 1.5 g of dried ginger) or placebo (soy bean
oil) 4 times daily for 4 days. No data were reported on
the preparation of the ginger extract. Outcomes included
the frequency, duration, and distress caused by the
symptoms of nausea, vomiting, and retching. Secondary
outcomes included gestational age, birth weight, and
occurrence of side effects and adverse effects on preg-
nancy outcomes such as abortion, stillbirth, congenital
abnormalities, and neonatal death. Pregnancy-related
symptoms were recorded 24 hours before and during the
4 days of treatment (4 time a day) using the Rhodes
Index of Nausea, Vomiting, and Retching (an 8-item,
5-point Likert-type tool). The follow-up of the study
included 81 women (women from the placebo and gin-
ger groups who were given an 18-day ginger supply
following the end of the trial). Outcomes were compared
with the general infant population delivered at the Royal
Hospital for Women in Sydney. The results showed a
signiﬁcant reduction in nausea experience, occurrence, and
distress in the ginger and in the placebo groups. However,
the reduction of nausea scores was signiﬁcantly higher in
the ginger than in the placebo group. Similar results were
observed for retching symptoms. There was no signiﬁcant
852 Borrelli et al Ginger and Pregnancy OBSTETRICS & GYNECOLOGY
difference between ginger extract and placebo groups for
any of the vomiting symptoms.
The most recent double-blind RCT involved 291
women (235 subjects completed the trial) between 8 and
16 weeks of gestation.
Subjects received either ginger
(350 mg) or vitamin B6 (25 mg) 3 times daily for 3 weeks.
Women were allowed to use other medications during
the trial (25% used an antiemetic, no data on the dosage
used). No information was reported on the preparation
of the ginger powder. Outcomes included both change in
nausea, dry retching, and vomiting episodes (from base-
line at days 7, 14, and 21, measured by the Rhodes Index
of Nausea and Vomiting, Form 2,
5-point Likert scale)
and improvement in health status (measured by the
Medical Outcomes Study 36-Item Short Form Health
Survey). The baseline pregnancy-related symptoms
were recorded for 3 days before treatment. Secondary
outcomes included the occurrence of side effects and
adverse pregnancy outcomes such as antepartum hem-
orrhage, pregnancy-induced hypertension, preeclamp-
sia, perinatal and neonatal death, preterm birth, and
congenital abnormalities. The results showed that ginger
was therapeutically equivalent to vitamin B6 in alleviat-
ing nausea, dry retching, and vomiting. However, 20%
of the pregnant women still continued to use antiemetics
at the end of the trial. A signiﬁcant difference was found
in the percentage of women reporting belching while
using ginger compared with those using vitamin B6 (9%
and 0% for ginger and vitamin B6 groups, respectively).
Five of the 6 RCTs
described above and 1
prospective observational cohort study (described in
speciﬁcally evaluated ginger safety in
pregnancy. Four RCTs, as well as the observational
study, investigated ginger-induced adverse effects on
and on the fetus (pregnancy out
Pregnancy outcomes, collected after
the delivery, included antepartum hemorrhage, pre-
eclampsia, preterm birth, perinatal and neonatal death,
congenital abnormalities, and birth weight. There were
no reports of adverse events during ginger treatment.
Adverse effects on pregnancies were observed in 4 of
6 clinical trials
. These included headache,
rhea and abdominal discomfort,
The follow-up of
showed no difference in the occurrence
of spontaneous abortions, stillbirth, term delivery and
cesarean deliveries, neonatal death, gestational age, and
congenital abnormalities between women who were ex-
posed to ginger and women exposed to vitamin B6
Similar results were found when the effect
of ginger on pregnancy outcomes was compared with the
The observational cohort comparative study involved
the enrollment of 187 pregnant women exposed to gin-
ger and 187 women exposed to nonteratogen drugs
(which were not antiemetics) in the ﬁrst trimester of
Among the 187 women exposed to ginger,
39% used ginger concurrently with an antiemetic drug.
All subjects answered a structured questionnaire that
elicited information about medical indication for ginger
use, dosage, frequency of administration, and timing of
exposure, as well as maternal demographics and obstet-
ric history. After the delivery, women were questioned
regarding the course of the pregnancy, the health of the
child, the speciﬁc details of the exposure to ginger, and
any other exposures or use of drugs during the preg-
nancy. Outcomes included the incidence of major mal-
formations (congenital anomalies and social acceptabil-
ity of the individual), rates of spontaneous or therapeutic
abortions, live births and stillbirths, gestational age at
birth, and birth weight. Dosage and origin of ginger were
not documented. No statistically signiﬁcant differences
between the 2 groups regarding live births, spontaneous
abortions, stillbirths, therapeutic abortions, birth weight,
or gestational age were found. A signiﬁcant difference
was detected in the rates of low birth weight infants, ie,
those weighing less than 2,500 g (1.6% and 6.4% in the
ginger and comparison groups, respectively; P ⬍ .05),
despite the presence of 8 sets of twins in the ginger group.
This systematic review suggests that ginger may be a safe
and effective option for the treatment of nausea and
vomiting in pregnancy. This ﬁnding corroborates the
results of previous inconclusive analyses based on less
These studies were from Australia (2
studies), Thailand (2 studies), Canada (1 study), and
Denmark (1 study). Whether or not demographic or
social/cultural similarities and differences among these
populations can be generalized to the universe of preg-
nant women worldwide cannot be extrapolated from the
present review. According to the Jadad score,
of the RCTs retrieved was good to excellent: adequate
blinding of participants and investigators, appropriate
method to generate the sequence of randomization, and
the presence of adequate control conditions. However,
several shortcomings have been noted.
Two clinical trials compared ginger with vitamin B6.
Both studies concluded that ginger was as effective as
vitamin B6 in reducing nausea and the number of vom-
However, it should be noted that the
efﬁcacy of vitamin B6 in the treatment of nausea and
vomiting in pregnancy is not compelling.
number of studies demonstrated that placebo treatment
853VOL. 105, NO. 4, APRIL 2005 Borrelli et al Ginger and Pregnancy
is useful in the relief of nausea.
For these reasons,
these comparative studies
should be viewed with
caution. Also, it should be noted that in one study
of women used conventional antiemetics during the trial.
Four clinical studies compared the efﬁcacy of ginger with
that of a placebo.
These studies were of good
methodological quality: women did not take other med-
ications during the trial,
the compliance of the
subjects was checked,
the severity of pregnancy-
related symptoms was recorded more than once per
and an objective measurement of the nausea
severity was obtained using 2 independent measurement
One of the main problems in crossover trials
is the possibility of a carryover effect of the active sub-
stance in the second treatment. In the study performed
by Fischer-Rasmussen et al,
a severity score was used
both to avoid a carryover effect of ginger and to objectify
the symptoms of hyperemesis. In all clinical trials, ginger
was taken 3 or 4 times a day, independently of the
occurrence of nausea and/or vomiting. Moreover, al-
though the single acute dose of ginger varied in each
study, the daily dose was approximately1gin5ofthe6
studies reviewed (with periods ranging from 8 to 20
A prospective observational cohort study and the
follow-up of 4 RCTs (reported above) consistently
showed that there are no signiﬁcant side effects or ad-
verse effects on pregnancy outcomes.
consistent with the results of the majority of animal
although a mutagenic activity has been docu
mented for an ethanolic ginger extract in vitro.
ever, the short duration of treatment periods and the
small number of patients taking ginger (n ⫽ 303) in
RCTs may have been insufﬁcient to properly test the
safety of the ginger with regard to pregnancy outcomes.
Moreover, the cohort study had a small sample size (n ⫽
187) and was based on a self-selected sample of women
who called a help line and may have differed in some
ways from the general population. An increase both in
the mean of the birth weight of the babies and in the
occurrence of multiple pregnancies (twins) has been
observed in the pregnancies exposed to ginger. The
increased birth weight is in line with clinical studies
reporting a lower birth weight in infants of women
experiencing nausea and vomiting during pregnancy.
However, the correlation between nausea and birth
weight has been recently questioned.
nism of the action of ginger on pregnancy symptoms has
not been fully identiﬁed although several hypotheses
have been proposed. It has been reported that symptoms
of nausea and vomiting during pregnancy improved in
direct correlation to the improvement in pregnancy-
induced gastric dysrhythmias.
duced reduction of pregnancy symptoms may be due to
a direct effect of the drug on the gastrointestinal tract.
The activity of ginger has been attributed to nonvolatile
pungent components, namely shogaols and gingerols.
In conclusion, considering the largely positive results
of RCTs and the absence of adverse effects on preg-
nancy outcomes, ginger may be an effective treatment in
managing nausea and vomiting symptoms during preg-
nancy. However, more observational studies and also
larger randomized clinical trials to make a deﬁnite state-
ment on the safety of ginger in pregnancy are needed.
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Address reprint requests to: Francesca Borrelli or Angelo A.
Izzo, Department of Experimental Pharmacology, University
of Naples Federico II, Via D. Montesano 49, 80131 Naples,
Italy; e-mail: firstname.lastname@example.org.
Received July 6, 2004. Received in revised form October 12, 2004.
Accepted December 2, 2004.
856 Borrelli et al Ginger and Pregnancy OBSTETRICS & GYNECOLOGY