Complementary & Integrative Health Approaches

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 American adults—report using these types of products and practices. Some complementary approaches for travel-related health problems are promoted widely, especially on the Internet. However, little of the promotional material is supported by research evidence, and some of it is misleading or false. This section focuses on claims that have been made about alleged benefits of complementary approaches for travel-related health problems and what the science says about some of the herbal products, dietary supplements (see Box 2-2), and other complementary approaches suggested for travel-related ailments and hazards.

Complementary Approaches to Travel Wellness: Claims vs. Science

Malaria Prophylaxis and Treatment


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).

Box 2-2. 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
  • 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, products marketed as dietary supplements have been found to contain illegal hidden ingredients such as prescription drugs.
  •  Consult the FDA’s safety advisories to learn the latest regarding product recalls and safety alerts:
  • Unproven therapies are discussed in this section only for educational purposes and are not recommended for use. CDC endorses only FDA-approved therapies.

What the Science Says

Urge patients to follow official recommendations and not rely on unproven “natural” approaches in an attempt to prevent or treat such a serious disease. Recommended drugs to prevent and treat malaria are described in Chapter 4, Malaria.

Zika Prophylaxis and Treatment


Consumer websites and online videos have claimed, without credible evidence, that various herbs or other natural products will protect against or treat the Zika virus.

What the Science Says

There is no evidence that any of these products can prevent or treat Zika virus infection. For more information see Chapter 4, Zika.

Travelers’ Diarrhea Prevention 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).

What the Science Says


Using probiotics for the prevention of TD is controversial. Although some studies have had promising results, meta-analyses have reached conflicting conclusions. It is difficult to interpret the evidence because studies have used a variety of microbial strains, some studies were not well controlled, and the optimal dose and duration of use have not been defined. For more information, see Traveler’s Diarrhea in this chapter.


No high-quality research on goldenseal for TD has been published. Studies show that goldenseal inhibits cytochrome P450 enzymes, raising concerns that it may increase the toxicity or alter the effects of drugs.

Activated Charcoal

No solid evidence supports 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. People who need to avoid grapefruit because it interacts with medicine that they are taking should also avoid grapefruit seed extract.

Altitude Illness Prevention and Treatment


A variety of natural products, including coca, garlic, Ginkgo biloba , and vitamin E, have been promoted for the prevention or treatment of altitude illness.

What the Science Says


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 10, 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 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 of drug interactions.

Ginkgo Biloba

Studies of ginkgo for preventing altitude illness have had inconsistent but mostly negative results. Whether the differences in results relate to the different preparations used in the studies has not been 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 anticoagulants. In addition, studies by the National Toxicology Program showed that rodents developed liver and thyroid tumors after being given a ginkgo extract for up to 2 years.

Vitamin E

One study investigated vitamin E, in combination with other antioxidants, for altitude illness; the results were negative.

For more information on altitude illness, see Chapter 3, High-Altitude Travel & Altitude Illness.

Motion Sickness


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

What the Science Says

Acupressure and Magnets

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 and may help control nausea related to cancer chemotherapy when used in addition to conventional medication, there is no strong evidence that ginger helps with motion sickness. In some people, ginger can have mild side effects such as abdominal discomfort. Research has not definitively 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 B 6 )

Although an American Congress of Obstetrics and Gynecology 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. Taking excessive doses of pyridoxine supplements for long periods of time can affect nerve function.

Homeopathic Products

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

Jet Lag/Sleep Problems


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.

What the Science Says


Some evidence suggests that melatonin supplements may help with sleep problems caused by jet lag. Recent systematic reviews indicate that it may be of some benefit for people traveling in either an eastward or westward direction. Before suggesting melatonin to your patients, 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. Side effects from melatonin are uncommon but can include drowsiness, headache, dizziness, or nausea.
  • Melatonin should not be taken early in the day, as it may cause sleepiness and delay adaptation to local time.
  • Melatonin is sold as a dietary supplement. Dietary supplements are regulated less strictly than drugs. The amounts of ingredients in dietary supplements may vary, and product contamination is a potential concern. A 2017 analysis of melatonin supplements sold in Canada found that their actual melatonin content ranged from –83% to +478% of the labeled content and that there was substantial lot-to-lot variation. Also, 26% of products contained serotonin as a contaminant.

Relaxation Techniques and Other Mind and Body Practices

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 whether they are effective for jet lag.

Aromatherapy and Herbs

There is very little evidence that aromatherapy or the herbs chamomile or valerian help with insomnia. Significant side effects are uncommon, but chamomile can cause allergic reactions. Another herb, kava, is also promoted for sleep but good research on its effectiveness is lacking. More importantly, kava supplements have been linked to a risk of severe liver damage.

Colds and Flu


Although colds and flu are not uniquely travel-related hazards, many people are concerned about trying to avoid these illnesses during a trip. They may turn to complementary health approaches that have been advocated for preventing or treating colds or flu, including zinc products, neti pots and other forms of saline nasal irrigation, vitamin C, probiotics, echinacea, and others.

What the Science Says


Zinc taken orally (often in the form of lozenges) 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.

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, distilled, boiled-then-cooled, or specially filtered 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 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 a cold starts does not. Vitamin C supplements appear safe, even at high doses.


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


Numerous studies have tested the herb echinacea to see whether it can prevent colds or relieve cold symptoms. 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 influenzalike illness.

Insect Protection: Botanical Repellents


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.

What the Science Says


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 OLE. There are no high-quality studies on the effectiveness or safety of neem oil for preventing mosquito bites (see Chapter 3, Mosquitoes, Ticks & Other Arthropods).

Bed bugs

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. Information is available on CDC’s website at and Box 3-2, Bed bugs and international travel.

Sun Protection


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

What the Science Says

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. For more information, see Chapter 3, Sun Exposure.

Homeopathic Vaccines


Proponents of homeopathy claim that products called “nosodes” or homeopathic vaccines are effective substitutes for conventional immunizations.

What the Science Says

There is no credible scientific evidence or plausible scientific rationale to support these claims. For more information, see Vaccination & Immunoprophylaxis: General Recommendations 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 Chapter 9.

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 ( to help you and your patients have a meaningful discussion about complementary approaches.


The authors thank Mr. Philip Kibak of ICF for his editorial assistance.


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David Shurtleff, Kathleen Meister, Catherine Law