MAJOR CHEMICAL CONSTITUENTS

The major chemical constituents are volatile oils, including β-bisabolene and zingiberene, sesquiterpenes, including zingiberol, zingiberenol, the oleoresin shaogol, numerous monoterpene hydrocarbons, alcohols, and aldehydes, oleoresins, free fatty acids including palmitic acid, oleic acid, linoleic acid, caprylic acid, capric acid, lauric acid, myristic acid, steric acid, and starch and amino acids.

PRINCIPAL USES

TRADITIONAL AND HISTORICAL USES

Ginger has been used traditionally from Asia to the Caribbean for its antispasmodic, carminative, and diaphoretic properties. It has been used in traditional Chinese medicine (TCM), for example, since at least the ninth century for the treatment of nausea, diarrhea, and digestive complaints. Ginger was included in the United States Pharmacopoeia (USP) and the National Formulary as a carminative, stimulant, and aromatic herb. Because of geographic/climatic distribution of the herb, its use was not reported in northern European traditional herbalism, but its place in modern Western herbalism has become firmly established, as described in this profile.

CLINICAL INDICATIONS

Modern use of ginger has focused on its efficacy as an antiemetic for the treatment of nausea and vomiting in a variety of contexts, including during pregnancy and for patients undergoing chemotherapy. It has also been used for the treatment of appetite loss in cases of HIV, cancer, and the side effects of medications for their treatment. Herbal practitioners also widely use ginger for the treatment of gynecologic pain, including dysmenorrhea, pain associated with uterine fibroids, and chronic pelvic pain. It is also used for the treatment of premenstrual headaches and for the relief of diarrhea and cramping bowel pain that often accompanies dysmenorrhea, PMS, and endometriosis.

Ginger (Zingiber officinalis).

(Photo by Martin Wall.)

IN VITRO, ANIMAL, AND CLINICAL DATA

Ginger has been shown to have antiemetic effects in animal and human studies, possibly through an antiserotinergic effect. In seemingly contradictory animal studies, the herb has been shown to both increase stomach acid production, possibly interfering with the effects of antacid medications, and to significantly reduce gastric secretions and provide gastric mucosal protection with a reduction in gastric ulcers comparable to the effects provided by NSAIDs. At 62 mg/kg ginger extract has demonstrated protective effects against stress ulcer induction in rats, although to a lesser extent than cimetidine. The antiplatelet effects of ginger are also controversial. Although the herb does inhibit prostaglandin, thromboxane, and leukotriene synthesis, inhibition of platelet synthesis has been inconsistent among studies. Ginger has demonstrated anti-inflammatory activity in vitro, with COX-2 inhibition and resultant reductions of severe arthritis, paw and joint swelling in rats treated with ginger oil. Fresh ginger juice has a hypoglycemic effect in nondiabetic and diabetic rabbits and rats, with the effect more pronounced in diabetic animals.

MECHANISMS OF ACTION

The aromatic principles of ginger are considered responsible for its medicinal actions, including enzymatic inhibition of prostaglandin, thromboxane, and leukotriene synthesis. The mechanisms of action on nausea and vomiting remain uncertain, with studies demonstrating increased gastric motility contradictory to those showing no motility. Another theory is that the herb acts via a centrally mediated effect on 5-hydroxytryptamine-3 (5-HT₃), an effect that has been demonstrated in vitro. There is some evidence that ginger increases stomach acid production, thus possibly interfering with antacid medications.

RATINGS

PREPARATIONS USED CLINICALLY

DOSAGE

SAFETY INFORMATION: HERB DRUG INTERACTIONS, TOXICITY, AND CONTRAINDICATIONS

Ginger has a long history of safe use both as a culinary and medicinal herb. It is considered safe when used as recommended, including when used within the prescribed pregnancy dose. Dose should not exceed 1 g daily in pregnancy, and 4 g per day for the general population. Theoretical herb drug interactions have been proposed (Table 1). Concerns have been expressed that ginger might increase the risk of bleeding, for example, with surgery, owing to platelet activating factor (PAF) inhibition; therefore, it is recommended that patients taking ginger should discontinue use 1 to 2 weeks prior to surgical procedures. Patients using oral hypoglycemic medications may require a dose adjustment as ginger may have hypoglycemic effects. Limited evidence suggests that ginger may interfere with antacids, sulcralfate, H2 antagonists, and proton pump inhibitors (PPIs) by increasing stomach acid production. Patients with gastric and duodenal ulcers are therefore sometimes advised to avoid using ginger other than for culinary purposes for this reason; however, animal experiments suggest a protective effect against gastric ulcers.

TABLE 1 Herb–Drug Interactions with Ginger

Patients with known allergy or hypersensitive to members of the Zingiberacae family, or those allergic to Balsam of Peru, may experience sensitivity or contact dermatitis with use of ginger. Ginger powder taken unencapsulated has been known to cause heartburn-like symptoms, and raw ginger taken in large boluses and poorly masticated has been reported in the literature to cause ileus in a limited number of case reports.

USE IN PREGNANCY AND LACTATION

A literature review identified six double-blind RCTs with a total of 675 participants and a prospective observational cohort study (n = 187) met all specified inclusion criteria. The methodologic 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 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.

In a study of pregnant women who called the Motherisk Program and who were taking ginger during the first trimester of pregnancy were enrolled in the study, the women were compared with a group of women who were exposed to nonteratogenic drugs that were not antiemetic medications. The women were followed to ascertain the outcome of the pregnancy and the health of their infants. They were also asked on a scale of 0 to 10 how effective the ginger was for their symptoms of NVP. Out of 187 pregnancies, there were 181 live births, two stillbirths, three spontaneous abortions, and one therapeutic abortion. The mean birth weight was 3542 g ± 543 g the mean gestational age was 39 ± 2 weeks, and there were three major malformations. There were no statistical differences in the outcomes between the ginger group and the comparison group with the exception of more infants weighing less than 2500 g in the comparison group (12 vs. 3, p< 0.001). These results suggest that ginger does not appear to increase the rates of major malformations above the baseline rate of 1% to 3% and that it has a mild effect in the treatment of NVP. Ginger has not been shown to cause teratogenesis in rat pregnancy models.

Perhaps one limit to the potential effectiveness of ginger as an antiemetic is suggested by a study that found tremendous variability in the contents of ginger products on the market, most notably the type of ginger used. Another limitation is that the studies cited in the literature review are time limited, whereas NVP and hyperemesis gravidarum are persistent problems of long duration (weeks to months) for which no remedy provides consistent, lasting relief.

Some studies reported side effects such as headache, diarrhea, and drowsiness, but there were no differences in pregnancy outcomes among women taking placebo, vitamin B₆, or ginger. Sipping ginger tea may actually aggravate nausea and vomiting in women who are triggered by larger volumes of fluid, as might swallowing ginger capsules; therefore, these women may be best served simply sipping tea, avoiding taking capsules on an empty stomach, or using other products such as ginger-flavored hard candies made with real ginger, crystallized ginger, or ginger ale made with real ginger.

Although several of the mentioned studies do not specify dose and product, in one of the most recent studies participants were randomly assigned to take a capsule containing 350 mg of ginger or one containing 25 mg of vitamin B₆ three times a day for 3 weeks.