Whether taken as a tea, in sweets, syrups or cookies, or in supplement form, ginger is one of the most popular natural remedies for nausea and vomiting. But is there any science behind it, and how does it compare to the standard drugs used for the same problem—the so-called 'antiemetics'? Let's take a look at the research.
There's plenty of evidence that ginger can be effective for nausea and vomiting in pregnancy, which is no doubt why it's recommended by alternative practitioners and conventional doctors alike.
In one trial, 77 percent of women given a ginger syrup drink (1 Tbsp of syrup in water, four times a day) experienced a significant improvement in nausea compared with only 20 percent of those taking a placebo. And more than three times the number of ginger-taking women stopped vomiting within six days of starting treatment compared with those taking the placebo.1
In another placebo-controlled study, eating ginger cookies proved to be an effective remedy for alleviating pregnancy-induced nausea and helped reduce vomiting too, although to a lesser extent.2
Ginger has even been pitted against commonly used drugs for nausea and vomiting in pregnancy like the antihistamine dimenhydrinate and dopamine antagonist metoclopramide. In a trial of 170 pregnant women carried out at Thammasat University Hospital in Bangkok, Thailand, 50 mg of ginger twice a day was just as effective as dimenhydrinate, but with fewer adverse effects like drowsiness.3
Ginger doesn't seem to be quite as effective as metoclopramide, according to one trial, but it was a very close call. "It could be a good alternative for metoclopramide," the researchers concluded.4
A number of researchers have looked at all the evidence on ginger for nausea and vomiting in pregnancy to assess its overall effectiveness. One review found that it worked for nausea, but not so much for vomiting,5 while another reported that ginger was significantly more effective than placebo in reducing both the frequency of vomiting and intensity of nausea.6
Less research has been carried out on ginger for motion sickness, but one study found that it was better than dimenhydrinate for relieving symptoms. A follow-up study reported that 1 g of ginger was effective for reducing seasickness severity in naval cadets on the high seas, although the results did not reach statistical significance.7
Other research, though, suggests that ginger is no better than a placebo for motion sickness.8
The evidence is more clear-cut for nausea and vomiting associated with surgery. In a high-quality trial of 60 women who had undergone major gynecological surgery, there were fewer incidences of nausea in those given ginger root compared to a placebo, and the efficacy of the spice was similar to that of metoclopramide.9
Similarly, ginger was just as good as metoclopramide for reducing postoperative nausea and vomiting in a study of 120 women undergoing gynecological surgery on an outpatient basis, and both worked better than a placebo.10
According to a pooled analysis of all such studies so far, a dose of at least 1 g of ginger "is more effective than placebo for the prevention of postoperative nausea and vomiting."11
Ginger is also showing promise for the nausea and vomiting that usually accompanies chemotherapy, although the studies have had mixed results. In one review of the evidence by researchers at the University of Queensland, Australia, three trials showed positive effects, two were in favor of ginger but with caveats, and two found no effect of ginger on chemo-induced nausea and vomiting.12
Safety and side-effects
Ginger's good track record for curbing different kinds of nausea and vomiting is good news for anyone wishing to avoid the side-effects associated with conventional antiemetic drugs. Ginger in general appears to be safe; adverse effects are uncommon but may include mild gastrointestinal upset such as heartburn and diarrhea.7
In contrast, antihistamines like dimenhydrinate can have sedative effects as well as cause dry mouth and blurred vision, while dopamine antagonists like metoclopramide have been linked to considerably more serious adverse effects, including tardive dyskinesia—a hard-to-treat, often incurable, neurological condition characterized by involuntary movements of the face, mouth, jaw and limbs.13 In fact, in 2009, the Food and Drug Administration (FDA) required all manufacturers of metoclopramide to issue a 'black-box warning' about the risk of tardive dyskinesia with chronic or high-dose use of the drug.14
As for the safety of these drugs during pregnancy, no evidence of harm to newborns has been found with metoclopramide, although one study found an association between the antihistamine diphenhydramine and cleft lip and palate.15
Several scientific reviews have found ginger safe for use during pregnancy, including one that involved more than 68,500 pregnant women, more than 1,000 of whom had taken ginger.16 But two small-scale studies found a marginal and non-significant increased risk of having small babies and stillbirths among women who reported using ginger during pregnancy.17
These studies had various limitations, though, such as a wide variability in the doses used and the possible use of other, confounding medications. In the end, while prescribed dosages can be as high as 12 g/day, many agree that ginger is safe for use in pregnancy as long as no more than 1-1.5 g/day is taken in divided doses.18
The bottom line
Ginger in a variety of forms appears to be an effective natural option for the nausea and vomiting associated with pregnancy, surgery, and possibly motion sickness and chemotherapy. When it comes to dosages, it's best to see a qualified herbalist, who can recommend what's best for you based on your individual circumstances.
If you're concerned about the safety of ginger during pregnancy, other effective options are supplementing with vitamin B6, and eating small and frequent meals.