People planning international travel often ask their health care providers about the use of complementary or integrative health approaches for travel-related illnesses and conditions. Some of these approaches for travel-related health problems are promoted widely in advertising or marketed on the Internet. However, little of this information is supported by research evidence, and some of it is misleading or false. This issue of the Digest focuses on what scientifically credible research says about some of the herbal remedies, dietary supplements, and other complementary health approaches frequently suggested for travel-related ailments and hazards.
Ailment and Summary of Current Evidence
Quinine from the cinchona tree (Cinchona spp.) may be used in combination with other antimalarial medications to treat malaria. There is no evidence that quinine prevents malaria. Travelers should not attempt to use quinine to self-treat or prevent malaria.
Although consumer websites and news stories have claimed that using the herb artemisia alone may prevent malaria, studies show it does not. The World Health Organization recommends against using artemisia plant material in any form (including tea) for treating or preventing malaria.
There is no evidence that any herbs or other products, such as activated charcoal or diatomaceous earth, will protect against or treat the Zika virus.
Research on the use of probiotics in treating acute infectious diarrhea is generally positive. Results from studies on preventing travelers’ diarrhea are mixed but encouraging. The U.S. Food and Drug Administration has not approved any health claims for probiotics.
There is no evidence to support the claims that activated charcoal helps with travelers’ diarrhea, bloating, stomach cramps, or gas. Children should not be given activated charcoal for diarrhea and dehydration, as it may absorb nutrients, enzymes, and antibiotics in the intestine and mask the severity of fluid loss.
Claims that grapefruit seed extract can prevent bacterial foodborne illnesses are unfounded and not supported by research.
There is little, if any, evidence that dietary or herbal supplements help prevent or treat altitude illness.
Using acupressure or magnets is advocated by some to prevent or treat motion sickness; however, research does not support the use of acupressure or magnets for this purpose.
Although some studies have shown that ginger may ease pregnancy-related nausea and vomiting, there is no strong evidence that ginger helps with motion sickness.
Although the American Congress of Obstetrics and Gynecology’s 2015 Practice Bulletin Summary recommends pyridoxine alone or in combination with doxylamine as a safe and effective treatment for nausea and vomiting associated with pregnancy, there is no evidence supporting claims that pyridoxine prevents or alleviates motion sickness.
Melatonin supplements may help with sleep problems caused by jet lag.
Relaxation techniques, such as progressive relaxation and mindfulness-based stress reduction, may help with insomnia, but it has not been established whether they are effective for jet lag.
Laboratory studies found that botanicals, including citronella products, worked for shorter periods than products containing DEET. For people who prefer to use botanicals, the Centers for Disease Control and Prevention recommends Environmental Protection Agency (EPA)-registered products containing oil of lemon eucalyptus (OLE), such as the products Repel and Off! Botanicals.
There are no high-quality studies on the effectiveness or safety of neem oil for preventing mosquito bites.
Sunscreens are promoted as containing aloe vera and green tea, among other natural ingredients, but studies have not proven that any herbal product or dietary supplement, including aloe, beta carotene, selenium, or epigallocatechin gallate (EGCG), an extract in green tea, reduce the risk of skin cancer or sun damage.
There is no credible scientific evidence or plausible scientific rationale to support claims that certain homeopathic products (sometimes called nosodes or homeopathic immunizations) are effective substitutes for conventional immunizations.