Discussing Complementary & Integrative Health Approaches with Travelers

Discussing Complementary & Integrative Health Approaches with Travelers

Travelers often ask their health care providers about the use of complementary or integrative health approaches for travel-related illnesses and conditions. This should come as no surprise, given that many people—approximately 1 in 3 Americans—report using products or practices that have origins outside of conventional medicine to complement treatment for a variety of medical conditions or to promote general wellness. Some of these approaches for travel-related health problems are promoted widely in advertising or discussed on the Internet. However, little of this information is supported by research evidence, and some of it is misleading or false. This section focuses on what scientifically credible research says about some of the herbal remedies, dietary supplements (see Box 2-9), and other complementary health approaches frequently suggested for travel-related ailments and hazards.

Box 2-9. About dietary supplements and unproven therapies

  • The Food and Drug Administration (FDA) regulates dietary supplements, but the regulations are different and generally less strict than those for prescription or over-the-counter drugs. Learn more at https://nccih.nih.gov/health/supplements/wiseuse.htm.
  • Two major safety concerns about dietary supplements are potential drug interactions and product contamination. Analyses of supplements sometimes find differences between labeled and actual ingredients. For example, an herbal supplement may not contain the correct plant species, or the amounts of the ingredients may be lower or higher than the label states.
  • Consult the FDA’s safety advisories to learn the latest regarding product recalls and safety alerts: www.fda.gov/Food/RecallsOutbreaksEmergencies/SafetyAlertsAdvisories/default.htm.
  • Unproven therapies are discussed in this section only for educational purposes and are not recommended for use. The Centers for Disease Control and Prevention (CDC) endorses only FDA-approved therapies.

Travel-related Ailments and Complementary Health Approaches

Malaria Prophylaxis and Treatment

Artemisia (Artemisia annua L. or sweet wormwood) and Quinine

Standard treatments for malaria in most of the world depend on plant derivatives. 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. An important component of the antimalarial drug artemether-lumefantrine comes from artemisinin, isolated from the qinghao plant (Artemisia annua ). Consumer websites and news stories have claimed that using the herb artemisia alone may prevent malaria, but 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. The use of artemisia alone has contributed to the increase in malaria parasites resistant to artemisinin. Recommended drugs used to prevent and treat malaria are described in Chapter 3, Malaria.

Vitamin and Mineral Supplements

Limited research suggests that when children with malaria are nutritionally deficient, supplements of vitamin A and zinc may help lower their fever and blood levels of the malaria parasite; however, there is no evidence that vitamin A or zinc prevent malaria infection. Vitamin A is fat soluble, and large or frequent doses may accumulate in the body and cause acute or chronic toxicity. High intake of vitamin A has been linked to birth defects. Taking beta-carotene, a precursor of vitamin A, has been linked to an increased risk of lung cancer and cardiovascular disease in some smokers. Zinc supplements can interact with several types of medications. Anyone taking high levels of zinc should be monitored for adverse health effects.

Zika Prophylaxis and Treatment

Consumer websites and online videos are claiming, without credible evidence, that herbs or other products, such as activated charcoal or diatomaceous earth, will protect against or treat the Zika virus. There is no evidence that any of these products can prevent or treat Zika virus infection. For more information see Chapter 3, Zika.

Travelers’ Diarrhea Prevention and Treatment


Probiotics are often suggested to help prevent travelers’ diarrhea (TD). Research on their use in treating acute infectious diarrhea is generally positive. Results from studies on preventing TD are mixed but encouraging. Given current data, it must be assumed that effects of probiotics in any given study are specific to the strain or strains tested. The US Food and Drug Administration (FDA) has not approved any health claims for probiotics.

In healthy people, probiotics usually have only minor side effects, if any. For more information see “Nonantimicrobial Drugs for Prophylaxis” in the Travelers’ Diarrhea section in this chapter.


Goldenseal is an herb that has been touted as a treatment for a variety of ailments. No high-quality research on goldenseal for TD has been conducted. Studies show that goldenseal inhibits cytochrome P450 enzymes, raising concerns that it may increase the toxicity or alter the effects of many commonly used drugs.

Activated Charcoal

There is no solid evidence to support claims that activated charcoal helps with TD, bloating, stomach cramps, or gas. The side effects of activated charcoal have not been well documented but were mild when it was tested on healthy people.

Warning: Children should not be given activated charcoal for diarrhea and dehydration. It may absorb nutrients, enzymes, and antibiotics in the intestine and mask the severity of fluid loss.

Grapefruit Seed Extract

Claims that grapefruit seed extract can prevent bacterial foodborne illnesses are unfounded and not supported by research.

Altitude Illness Prevention and Treatment

There is little, if any, evidence that dietary or herbal supplements help prevent or treat altitude illness (often referred to as mountain sickness).


Coca tea has been used for altitude illness, but there is no strong evidence on whether it works or has adverse effects. It will result in a positive drug test for cocaine metabolites. For more information see Chapter 4, Peru: Cusco, Machu Picchu, & Other Regions.


There is no evidence supporting claims that garlic helps reduce altitude illness. Garlic supplements appear safe for most adults. Possible side effects of taking garlic include breath and body odor, heartburn, and upset stomach. Some people have allergic reactions to garlic. Short-term use of most commercially available garlic supplements poses only a limited risk for causing herb–drug interactions, including interfering with the effectiveness of the HIV drug saquinavir.

Ginkgo Biloba

Results from several small studies of ginkgo for preventing altitude illness show conflicting, but mostly negative, results. Whether these differences relate to the different preparations used in these studies cannot be determined. Products made from standardized ginkgo leaf extracts appear to be safe when used as directed. However, ginkgo may increase the risk of bleeding in some people and interact with certain conventional medications, including anticoagulants. In addition, studies by the National Toxicology Program showed that rodents developed tumors after being given a ginkgo extract for up to 2 years.

Vitamin E

Only one small study has investigated vitamin E, in combination with other antioxidants, for altitude illness, and the results were negative. Taking supplements of vitamin E, a fat-soluble vitamin, has been linked to an increased risk of hemorrhagic stroke. They also have the potential to interact with several types of medications, including statins, niacin, and warfarin.

Motion Sickness Prevention and Treatment

Acupressure and Magnets

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. Several studies have found no evidence of harm from taking ginger during pregnancy, but it’s uncertain whether ginger is always safe for pregnant women; women should always talk with their health care provider before trying any dietary supplements during pregnancy, especially if traveling overseas. In some people, ginger can have mild side effects such as abdominal discomfort. Research has not definitely shown whether ginger interacts with medications, but concerns have been raised that it might interact with anticoagulants. The effect of using ginger supplements with common over-the-counter drugs for motion sickness (such as dimenhydrinate [Dramamine]) is unknown.

Pyridoxine (Vitamin B6)

While 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. Excessive use of pyridoxine supplements can affect nerve function.

Homeopathic Products

There is no evidence supporting claims that homeopathic products prevent or alleviate motion sickness.

Jet Lag/Sleep Problems


Melatonin supplements may help with sleep problems caused by jet lag. Travelers report having less jet lag on eastward and westward flights when given melatonin compared with placebo. In a 2007 clinical practice guideline, the American Academy of Sleep Medicine supported using melatonin to reduce jet lag symptoms and improve sleep after traveling across >1 time zone. A systematic literature review suggested taking 0.5–5 mg of melatonin appeared to be effective for easing jet lag.

Before recommending melatonin, consider the following:

  • People with epilepsy or who take an oral anticoagulant should never use melatonin without medical supervision.
  • Melatonin supplements appear to be safe for most people when used short-term; less is known about their long-term safety.
  • Melatonin should not be taken early in the day, as it may cause sleepiness and delay adaptation to local time.
  • The amount of melatonin in products and the dosages recommended on labels can vary significantly.

Side effects from melatonin are uncommon but can include drowsiness, headache, dizziness, or nausea.

Relaxation Techniques

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.


There is very little evidence that aromatherapy, chamomile, or valerian help with insomnia. None have significant side effects, but chamomile can cause allergic reactions. Kava is also advertised for sleep but good research on kava for insomnia is lacking. More importantly, kava supplements have been linked to a risk of severe liver damage.

For more information see the Jet Lag section in this chapter.

Colds and Flu


Zinc supplements taken orally may reduce the duration of a cold. Zinc, particularly in large doses, can have side effects including nausea and diarrhea. The intranasal use of zinc can cause anosmia (loss of sense of smell), which may be long-lasting or permanent. In 2009, the FDA warned consumers to stop using several intranasal zinc products that had been linked to cases of anosmia.

Saline Irrigation

Nasal saline irrigation, such as with neti pots, may be useful and safe for chronic sinusitis. However, even in places where tap water is safe to drink, people should use only sterile or distilled water for nasal irrigation to avoid the risk of introducing waterborne pathogens. Nasal saline irrigation may help relieve the symptoms of acute upper respiratory tract infections, but the evidence is not definitive.

Vitamin C

Taking vitamin C supplements regularly may slightly reduce the duration and severity of colds in some people. Vitamin C supplements appear safe, even at high doses.


Probiotics might reduce susceptibility to colds or other upper respiratory tract infections and the length of the illnesses, but the quality of the evidence is low or very low.


There is no strong evidence that echinacea, 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 influenzalike illness.

Other Common or Travel-Related Infections

Hepatitis C

Herbal supplements should never be used to treat hepatitis C outside of well-designed, randomized clinical trials. A randomized clinical trial found no evidence of benefit from silymarin (an extract from milk thistle seeds) in patients with chronic hepatitis C. In addition, a systematic review of 10 randomized clinical trials found no firm evidence of efficacy of any herbal supplements for hepatitis C. Two of the trials studied a single herb or herbal ingredient; the others studied different compounds made from herbs.

Vaginal Infections and Urinary Tract Infections

Probiotics have been studied for treating vaginal or urinary tract infections, but there is not enough supporting evidence to suggest that they are helpful.

Insect Protection: Botanical Repellents


Laboratory-based studies found that botanicals, including citronella products, worked for shorter periods than products containing DEET. For people wishing to use botanicals, CDC 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. Neem oil is used in agricultural insecticide products and promoted on some websites for human use.

Bed Bugs

Essential oils and other natural products are marketed for travelers to repel bed bugs, but there is no evidence that they are effective. Experts recommend against using any insect repellents or pesticides on clothing or luggage. Instead, travelers should be encouraged to follow steps to detect and avoid bed bugs, such as inspecting their mattress and keeping their luggage off the floor or bed. A guide for the public, How to Find Bed Bugs , is available at www.epa.gov/bedbugs/how-find-bed-bugs. Information is also available on CDC’s website at www.cdc.gov/parasites/bedbugs. For more information see Box 2-5.


Skin cancer is the most common type of cancer in the United States. Experts recommend using a broad-spectrum sunscreen, limiting your sun exposure, and wearing protective clothing to protect against sunburns and to possibly lower the risk of skin cancer. There are many “natural” sunscreen products available online, recipes for making your own, and advice on consuming dietary supplements or drinking teas to protect against sun damage. 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. For more information see Sun Exposure in this chapter.

Homeopathic Vaccines

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. For more information see General Recommendations for Vaccination & Immunoprophylaxis in this chapter.

Untested Therapies in Other Countries

CDC does not recommend traveling to other countries for untested medical interventions or to buy medications that are not approved in the United States. For more information see Medical Tourism in this chapter.

Talking To Travelers about Complementary Health Approaches

Given the vast number of complementary or integrative interventions and the wealth of potentially misleading information about them that can be found on the Internet, discussing the use of these approaches with patients may seem daunting. However, it is important to be proactive, as surveys show that many patients are reluctant to raise the topic with their health care providers. Federal agencies, such as the National Center for Complementary and Integrative Health (NCCIH), offer evidence-based resources (nccih.nih.gov/health/providers) to help you and your patients have a meaningful discussion about complementary approaches.


The authors thank Dr. John Williamson of NCCIH for his scientific review and Ms. Karen Kaplan and Ms. Patricia Andersen of Westat for their editorial assistance.


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Catherine Law, Tina Adler, David Shurtleff