Ginger is well-known for alleviating nausea and improving digestion. One gram of encapsulated ginger powder was used in one study to reduce the severe nausea and vomiting associated with hyperemesis gravidarum.¹⁸ This condition is potentially life-threatening and should only be treated by a qualified healthcare professional. A review of six double-blind trials concluded that ginger is probably an effective treatment for nausea and vomiting in pregnancy.¹⁹

Because ginger contains some compounds that cause chromosomal mutation in the test tube, some doctors are concerned about the safety of using ginger during pregnancy. However, the available clinical research, combined with the fact that ginger is widely used in the diets of many cultures, suggests that prudent use of ginger for morning sickness is probably safe in amounts up to 1 gram per day.²⁰

Ginger may be useful for the prevention and treatment of mild to moderate cases of motion sickness. A double-blind trial examined the effects of ginger supplements in people who were susceptible to motion sickness. Researchers found that those taking 940 mg of powdered ginger in capsules experienced less motion sickness than those who took dimenhydrinate (Dramamine).²¹ Another double-blind trial reported that 1 gram of powdered ginger root, compared with placebo, lessened seasickness by 38% and vomiting by 72% in a group of naval cadets sailing in heavy seas.²² Two clinical trials, one with adults and one with children, found that ginger was as effective in treating seasickness as dimenhydrinate but with fewer side effects.^23,24 In one controlled trial, though, neither powdered ginger (500 to 1,000 mg) nor fresh ginger (1,000 mg) provided any protection against motion sickness.²⁵ Doctors prescribing ginger for motion sickness recommend 500 mg one hour before travel and then 500 mg every two to four hours as necessary. The study with children used one-half the adult amount.

Ginger’s beneficial effect on motion sickness appears to be related to its action on the gastrointestinal tract rather than on the central nervous system.^26,27

Carminatives (also called aromatic digestive tonics or aromatic bitters) may be used to relieve symptoms of indigestion, particularly when there is excessive gas. It is believed that carminative agents work, at least in part, by relieving spasms in the intestinal tract.²⁸

There are numerous carminative herbs, including European angelica root (Angelica archangelica), anise, Basil, cardamom, cinnamon, cloves, coriander, dill, ginger, oregano, rosemary, sage, lavender, and thyme.²⁹ Many of these are common kitchen herbs and thus are readily available for making tea to calm an upset stomach. Rosemary is sometimes used to treat indigestion in the elderly by European herbal practitioners.³⁰ The German Commission E monograph suggests a daily intake of 4–6 grams of sage leaf.³¹ Pennyroyal is no longer recommended for use in people with indigestion, however, due to potential side effects.

Demulcents herbs may be used to treat indigestion and heartburn. These herbs seem to work by decreasing inflammation and forming a physical barrier against stomach acid or other abdominal irritants. Examples of demulcent herbs include ginger, licorice, and slippery elm.

Ginger is a spice well known for its traditional use as a treatment for a variety of gastrointestinal complaints, ranging from flatulence to ulcers. Ginger has anti-inflammatory and anti-nausea properties. Ginger has been shown to enhance normal, spontaneous movements of the intestines that aid digestion.³²

Whole peppermint leaf is often used either alone or in combination with other herbs to treat abdominal discomfort and mild cramping that accompany IBS. The combination of peppermint, caraway seeds, fennel seeds, and wormwood was reported to be an effective treatment for upper abdominal complaints in a double-blind trial.³³

Herbalists often use ginger to decrease inflammation and the pain associated with it, including for those with low back pain. They typically suggest 1.5 to 3 ml of ginger tincture three times per day, or 2 to 4 grams of the dried root powder two to three times per day. Some products contain a combination of curcumin and ginger. However, no research has investigated the effects of these herbs on low back pain.

Ginger is another Ayurvedic herb used to treat people with arthritis. A small number of case studies suggest that taking 6–50 grams of fresh or powdered ginger per day may reduce the symptoms of RA.³⁷ A combination formula containing ginger, turmeric, boswellia, and ashwagandha has been shown in a double-blind trial to be slightly more effective than placebo for RA;³⁸ the amounts of herbs used in this trial are not provided by the investigators.

Ginger has been used in some systems of traditional medicine to treat dysmenorrhea. In a double-blind trial, ginger powder was as effective as anti-inflammatory medication (mefenamic acid and ibuprofen) in relieving symptoms of dysmenorrhea. Ginger was used in the amount of 250 mg four times per day, beginning at the start of menstruation and continuing for three days.³⁹ In another double-blind trial, 500 mg of ginger taken 3 times per day, beginning 2 days before menstruation and continuing for the first 3 days of the menstrual period, significantly decreased the duration and severity of menstrual pain, compared with a placebo. The treatment was somewhat less effective if it was started at the beginning of menstruation, rather than 2 days before.⁴⁰

Ginger has been used in some systems of traditional medicine to treat dysmenorrhea. In a double-blind trial, ginger powder was as effective as anti-inflammatory medication (mefenamic acid and ibuprofen) in relieving symptoms of dysmenorrhea. Ginger was used in the amount of 250 mg four times per day, beginning at the start of menstruation and continuing for three days.⁴² In another double-blind trial, 500 mg of ginger taken 3 times per day, beginning 2 days before menstruation and continuing for the first 3 days of the menstrual period, significantly decreased the duration and severity of menstrual pain, compared with a placebo. The treatment was somewhat less effective if it was started at the beginning of menstruation, rather than 2 days before.⁴³

Herbalists often use ginger to decrease inflammation and the pain associated with it, including for those with low back pain. They typically suggest 1.5 to 3 ml of ginger tincture three times per day, or 2 to 4 grams of the dried root powder two to three times per day. Some products contain a combination of curcumin and ginger. However, no research has investigated the effects of these herbs on low back pain.

A recent study found that 24% of surgery patients had taken herbal supplements before their surgeries, and 50 different herbs had been used among these patients.⁴⁷ Little research exists, however, on the safety or efficacy of herbs before surgery. Some researchers and healthcare providers are concerned about possible harmful interactions between herbs and medications used around or during surgery, or the possibility that some herbs may increase bleeding during and after surgery.^48,49 The use of herbs around the time of surgery should be discussed with a knowledgeable healthcare practitioner.

Nausea and vomiting can be experienced post-operatively as a result of anesthesia. Ginger (Zingiber officinale) has antinausea properties and has been examined for its ability to prevent post-operative nausea and vomiting in several controlled trials. In two of these controlled trials, ginger was found more effective than placebo and equal to an antinausea medication;^50,51 however, in two other controlled trials ginger was not found to have any benefit.^52,53 A review considering the results of these trials concluded that 1 gram of ginger taken before surgery prevents nausea and vomiting slightly better than placebo, but this difference is not significant.⁵⁴ However, a more recent review concluded that ginger is an effective means for reducing postoperative nausea and vomiting.⁵⁵

The Chinese herb bupleurum, as part of the herbal formula sho-saiko-to, has been shown to have beneficial immune effects on white blood cells taken from people infected with HIV.⁵⁶ Sho-saiko-to has also been shown to improve the efficacy of the anti-HIV drug lamivudine in the test tube.⁵⁷ One preliminary study found that 7 of 13 people with HIV given sho-saiko-to had improvements in immune function.⁵⁸ Double-blind trials are needed to determine whether bupleurum or sho-saiko-to might benefit people with HIV infection or AIDS. Other herbs in sho-saiko-to have also been shown to have anti-HIV activity in the test tube, most notably Asian scullcap.⁵⁹ Therefore studies on sho-saiko-to cannot be taken to mean that bupleurum is the only active herb involved. The other ingredients are peony root, pinellia root, cassia bark, ginger root, jujube fruit, Asian ginseng root, Asian scullcap root, and licorice root.

One gram of powdered ginger (Zingiber officinale) root in a single application has been reported to significantly reduce symptoms of artificially induced vertigo in one double-blind trial.⁶⁰ In a double-blind trial, 1 gram of powdered ginger root was found to have very little effect in reducing vertigo related to seasickness.⁶¹

The research on ginger’s ability to reduce platelet stickiness indicates that 10 grams (approximately 1 heaping teaspoon) per day is the minimum necessary amount to be effective.⁶² Lower amounts of dry ginger,⁶³ as well as various levels of fresh ginger,⁶⁴ have not been shown to affect platelets.

The Japanese herbal formula known as sho-seiryu-to has been shown to reduce symptom, such as sneezing, for people with hay fever.⁶⁵ Sho-seiryu-to contains licorice, cassia bark, schisandra, ma huang, ginger, peony root, pinellia, and asiasarum root.