British Journal of Anaesthesia 84 (3): 367–71 (2000)
Efficacy of ginger for nausea and vomiting: a systematic review of
randomized clinical trials
E. Ernst* and M. H. Pittler
Department of Complementary Medicine, School of Postgraduate Medicine and Health Sciences, University of Exeter, 25 Victoria Park Road, Exeter EX2 4NT, UK Ginger (Zingiber officinale) is often advocated as beneficial for nausea and vomiting. Whetherthe herb is truly efficacious for this condition is, however, still a matter of debate. We haveperformed a systematic review of the evidence from randomized controlled trials for or againstthe efficacy of ginger for nausea and vomiting. Six studies met all inclusion criteria and werereviewed. Three on postoperative nausea and vomiting were identified and two of thesesuggested that ginger was superior to placebo and equally effective as metoclopramide. Thepooled absolute risk reduction for the incidence of postoperative nausea, however, indicateda non-significant difference between the ginger and placebo groups for ginger 1 g taken beforeoperation (absolute risk reduction 0.052 (95% confidence interval –0.082 to 0.186)). One studywas found for each of the following conditions: seasickness, morning sickness and chemotherapy-induced nausea. These studies collectively favoured ginger over placebo.
Br J Anaesth 2000; 84: 367–71
Keywords: pharmacology, ginger; vomiting, nausea; vomiting, incidence; research, emesis;
clinical trials
Accepted for publication: September 1, 1999 Ginger (Zingiber officinale) has been used for medicinal purposes since antiquity. In particular, it has been an Systematic literature searches were performed to identify important plant for the traditional Chinese and Indian all RCTs on ginger for nausea and vomiting. Computerized pharmacopoeia. One of its indications has always been the treatment of nausea and vomiting. The aromatic, spasmolytic CISCOM (Research Council for Complementary Medicine, carminative and absorbent properties of ginger suggest that London) and the Cochrane Library (all from their respective it has direct effects on the gastrointestinal tract.1 German inception to November 1997). The search terms used were and European monographs on ginger are available2 3 and ginger, Zingiber officinale and Ingwer (German term for both list nausea/vomiting as indications. Recently, the US Zingiber officinale). A manual search was performed using pharmacopoeia has approved ginger and powdered ginger the bibliographies of studies and reviews located through monographs for inclusion in the National Formulary.4 the computer search and through scanning our own files.
The notion that ginger may be effective for nausea and In addition, manufacturers of ginger preparations were vomiting is supported by several lines of evidence. Animal asked to contribute published and unpublished material. No experiments suggest that ginger has antiemetic activity5 when nausea is induced by cisplatin6 or cyclophosphamide.7 Only double-blind, placebo-controlled RCTs of ginger Studies in healthy human volunteers suggest that ginger monopreparations for nausea and vomiting were included.
reduces experimentally induced nausea.8 9 Furthermore, Studies on experimentally induced nausea or vomiting, or non-randomized, non-placebo-controlled studies suggest an both, were excluded. All studies were assessed independ- antiemetic effect in human patients.10 11 However, these ently by both authors. Data were extracted in a standardized, data are insufficient to evaluate whether or not ginger is predefined manner. The methodological quality of each truly efficacious for clinical nausea and vomiting.
study was assessed using the scoring system developed by In this study, we have assessed the available evidence Jadad and colleagues.12 The authors met to agree consensus from randomized, controlled trials (RCT) for or against the on the assessed data. Disagreements were settled by dis- efficacy of ginger for clinical nausea and vomiting.
The Board of Management and Trustees of the British Journal of Anaesthesia 2000 Statistical combination of data was performed for studies women before laparoscopic surgery to one of three similar on postoperative nausea. The incidence of postoperative treatment groups. The medication was given 1 h before nausea was defined as the common end-point and used to surgery and the incidence of nausea and vomiting was 21%, assess differences between treatment and control interven- 27% and 41% in the ginger, metoclopramide and placebo tion. The absolute risk reduction and 95% confidence groups, respectively. Significantly (Pϭ0.006) fewer patients intervals were calculated using standard meta-analysis with nausea were reported in the ginger group compared software (RevMan 3.01, Cochrane Collaboration). The num- ber-needed-to-treat was calculated as the inverse of the In a study by Arfeen and colleagues,20 108 women were allocated randomly to receive ginger 0.5 g, ginger 1 g orplacebo before laparoscopic surgery. The incidence ofnausea and vomiting was monitored 3 h after operation.
There were no significant differences between groups.
Six studies met all of our criteria and were reviewed.15–20 Data from RCT on postoperative nausea18–20 were suitable The assessment of methodological quality revealed a score for statistical pooling. The pooled absolute risk reduction of at least 3 of 5 points in the majority of studies.
for the incidence of postoperative nausea indicated a non- The studies related to four different clinical conditions: significant difference between the ginger group treated with ginger 1 g before operation and the placebo group (absolute nausea and postoperative nausea. Most were conducted on risk reduction 0.052 (95% confidence interval –0.082 to postoperative nausea.18–20 Key data are summarized in 0.186)). These values indicate a point estimate of the number-needed-to-treat of 19 and a 95% confidence interval Grøntved and colleagues15 studied 80 Danish cadets, which also includes the possibility of no benefit.21 allocated randomly to receive either one dose of gingerpowder 1 g or placebo. Symptoms of seasickness were Discussion
evaluated during the subsequent 4 h. Volunteers who The majority of the studies reported that ginger powder 1 g received ginger powder suffered less seasickness compared daily alleviated clinical nausea of diverse causes. One study with those who received placebo. The difference between on postoperative nausea,20 however, showed no significant ginger powder and placebo was statistically significant beneficial effects of ginger compared with placebo and, (PϽ0.05) 4 h after receiving the medication.
indeed, between doses of 0.5 g and 1 g of ginger powder.
Fischer-Rasmussen and colleagues16 conducted a small This study is also the most rigorous on this indication. The crossover study in 27 women suffering from hyperemesis discrepancy between this negative outcome and the positive gravidarum. Patients received ginger powder 250 mg or results from other RCT is not readily explicable.
placebo, four times daily for 4 days. Sickness was assessed There are only few data on the actions of ginger.
using a symptom score. The results suggested a significantly Gingerols, in particular 6-gingerol, have been identified as (PϽ0.05) greater symptomatic benefit after administration the active ingredient of ginger, and are also responsible for its characteristic taste. There are several mechanisms which One RCT was identified for chemotherapy-induced could explain the possible antiemetic effects of ginger. In nausea.17 Forty-one patients suffering from leukaemia were an animal model, for instance, it was demonstrated that allocated randomly to one of two groups to receive either 6-gingerol enhanced gastrointestinal transport.22 This and oral ginger or placebo, after administration of compazine other compounds of ginger have also been shown to i.v. The results suggested a significant (P value not reported) have anti-hydroxytryptamine activity in isolated guineapig reduction in nausea in patients who received ginger com- ileum.23 24 Galanolactone, another constituent of ginger, is pared with those who received placebo. This study has only a competitive antagonist at ileal 5-HT3 receptors.24 Thus been published as an abstract and crucial details were antiemesis could be brought about by effects on the gastric system through 5-HT3 antagonism. This hypothesis is Bone and colleagues18 studied 60 women before major weakened by the results of a randomized, placebo-con- gynaecological operations. Patients were allocated randomly trolled, crossover study in human volunteers reporting that to receive ginger 1 g, metoclopramide 10 mg or placebo as oral ingestion of powdered ginger root did not affect gastric a single dose given with preoperative medication. The emptying rate.25 In contrast, effects on the central nervous severity of postoperative nausea was assessed on a four- system may be involved. This notion is strengthened by the point scale. The incidence of nausea during the first 24 h finding that, in an animal model, oral 6-gingerol prevented after surgery was 28%, 30% and 51% in the ginger, vomiting in response to cyclophosphamide.7 A central effect metoclopramide and placebo groups, respectively. A statist- is also implicated by studies reporting that ginger partly ically significant (PϽ0.05) difference in favour of ginger prevents motion sickness symptoms in healthy human compared with placebo was reported for the total number volunteers.8–9 Another study investigating motion sickness, however, reported no effects of ginger on the vestibular Phillips, Hutchinson and Ruggier19 randomized 120 Efficacy of ginger for nausea and vomiting Duration
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