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NCCIH Clinical Digest

for health professionals

Travel-Related Ailments and Complementary Health Approaches

June 2022
travel related illness

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. 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

Many consumer websites promote “natural” ways to prevent or treat malaria, which often involve dietary changes or herbal products, such as quinine from the cinchona tree (Cinchona spp.) or extracts and material from the artemisia plant (Artemisia annua L. or sweet wormword).

Travelers should follow official recommendations and not rely on unproven “natural” approaches in an attempt to prevent or treat such a serious disease. 

Read more on what the research shows about complementary health approaches for malaria prophylaxis and treatment

It has been claimed that a variety of products, including probiotics, goldenseal, activated charcoal, and grapefruit seed extract, can prevent or treat travelers’ diarrhea (TD).

  • Although some studies on probiotics for the prevention of TD had promising results, meta-analyses have reached conflicting conclusions. 
  • No high-quality research on goldenseal for TD has been published. 
  • There is no evidence to support the claims that activated charcoal helps with TD, bloating, stomach cramps, or gas. 
  • Claims that grapefruit seed extract can prevent bacterial foodborne illnesses are not supported by research. 

Read more on what the research shows about complementary health approaches for travelers' diarrhea

There is little, if any, evidence that dietary or herbal supplements help prevent or treat altitude illness.

Read more on what the research shows about complementary health approaches for altitude illness

Complementary approaches marketed for preventing or treating motion sickness include acupressure, magnets, ginger, pyridoxine (vitamin B6), and homeopathic remedies.

  • Research does not support the use of acupressure or magnets for motion sickness.
  • Although some studies have shown that ginger may ease pregnancy-related nausea and vomiting, there is no strong evidence that it helps with motion sickness.
  • There is no evidence supporting claims that homeopathic products prevent or alleviate motion sickness. 
  • Although an American College of Obstetricians and Gynecologists 2015 Practice Bulletin Summary recommends pyridoxine (vitamin B6) alone or in combination with doxylamine (an antihistamine) 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.

Read more on what the research shows about complementary health approaches for motion sickness

Complementary approaches that have been suggested for jet lag or other sleep problems include the dietary supplement melatonin; relaxation techniques and other mind and body practices; aromatherapy; and herbs such as chamomile, kava, and valerian.

  • Some evidence suggests that melatonin supplements may help with sleep problems caused by jet lag in people traveling either east or west.
  • Relaxation techniques, such as progressive relaxation, and other mind and body practices, such as mindfulness-based stress reduction, may help with insomnia, but it has not been established if they are effective for jet lag.
  • There is very little evidence that aromatherapy or the herbs chamomile or valerian help with insomnia.
  • Another herb, kava, is also promoted for sleep but good research on its effectiveness is lacking. In addition, the use of kava has been linked to liver injury that is sometimes serious or even fatal. The exact cause and frequency of the liver damage are unclear.

Read more on what the research shows about complementary health approaches for jet lag/sleep problems

Many products are promoted as “natural” insect repellents, and their use may appeal to people who prefer not to use synthetic products. Products promoted as natural mosquito repellents include citronella products, oil of lemon eucalyptus (OLE), and neem oil (a component of agricultural insecticide products that is promoted on some websites for home use). Essential oils and other natural products are promoted to repel bed bugs.

  • Laboratory studies on mosquitoes 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 (CDC) recommends Environmental Protection Agency (EPA)-registered products containing OLE.
  • The evidence does not support the use of neem oil as a natural repellent against mosquitoes. 
  • There is no evidence that the natural products marketed to repel bed bugs are effective. Instead, travelers should be encouraged to follow steps to detect and avoid bed bugs, such as inspecting their mattresses and keeping their luggage off the floor or bed.

Read more on what the research shows about complementary health approaches for insect protection

Many “natural” sunscreen products are promoted online, as are recipes for making your own along with advice on consuming dietary supplements or drinking teas to protect against sun damage.

Studies have not proven that any herbal product or dietary supplement, including aloe vera, beta carotene, selenium, or epigallocatechin gallate (EGCG), an extract from green tea, reduces the risk of skin cancer or sun damage. 

Read more on what the research shows about complementary health approaches as sunscreen

There is no credible scientific evidence or plausible scientific rationale to support claims that products called “nosodes” or homeopathic vaccines are effective substitutes for conventional immunizations.

Read more on what the research shows about homeopathic vaccines

Although colds and flu are not uniquely travel-related hazards, many people try to avoid these illnesses during a trip. Complementary health approaches that have been advocated for preventing or treating colds or flu include zinc products; neti pots and other forms of saline nasal irrigation; vitamin C; probiotics; echinacea; and other herbs.

  • Taking zinc orally (often in the form of lozenges) may reduce the duration of a cold.
  • Nasal saline irrigation, such as with neti pots, may be useful and safe for chronic sinusitis. It may also help relieve the symptoms of acute upper respiratory tract infections, but the evidence is not definitive.
  • Taking vitamin C supplements regularly reduces the risk of catching a cold among people who perform intense physical exercise but not in the general population. Taking vitamin C on a regular basis may lead to shorter colds but taking it only after cold symptoms appear does not. 
  • The quality of the evidence is very low that probiotics might reduce susceptibility to colds or other upper respiratory tract infections and the duration of the illnesses. 
  • A 2014 systematic review concluded that echinacea has not been convincingly shown to be effective; however, a weak effect has not been ruled out.
  • There is no strong evidence that garlic, Chinese herbs, oil of oregano, or eucalyptus essential oil prevent or treat colds, or that the homeopathic product Oscillococcinum prevents or treats influenza or influenza-like illness.

Read more on what the research shows about colds and flu

NCCIH Clinical Digest is a service of the National Center for Complementary and Integrative Health, NIH, DHHS. NCCIH Clinical Digest, a monthly e-newsletter, offers evidence-based information on complementary health approaches, including scientific literature searches, summaries of NCCIH-funded research, fact sheets for patients, and more.

The National Center for Complementary and Integrative Health is dedicated to exploring complementary health products and practices in the context of rigorous science, training complementary health researchers, and disseminating authoritative information to the public and professionals. For additional information, call NCCIH’s Clearinghouse toll-free at 1-888-644-6226, or visit the NCCIH website at NCCIH is 1 of 27 institutes and centers at the National Institutes of Health, the Federal focal point for medical research in the United States.


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