Harmful Chemicals in Mosquito Repellent

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Harmful Chemicals in Mosquito Repellent

When used as directed, insect repellents can reduce the effects of mosquitoes and other biting insects and can even help prevent certain insect-borne illnesses such as malaria and West Nile virus. If used improperly, repellents can be harmful. We'll consider the most popular active ingredients in insect repellents today and their potential risks.


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DEET is one of the most widely used chemicals as a mosquito repellent. While the use of DEET in lower concentrations is considered safe, when used in concentrations greater than 50 percent, DEET can produce skin irritation. Eye irritation is also common. DEET also will penetrate skin and can, in rare instances, affect the central nervous system. In some individuals, slurred speech, confusion and seizures have occurred. These symptoms are most commonly associated with long-term, excessive exposure or improper use.



Permethrin is another repellent intended for treating clothing and other items, such as tents, sleeping bags and other gear made of fabric. Permethrin can cause eye irritation. While pyrethroid chemicals directly affect the nervous system of insects, it is not certain how these chemicals will affect humans, so care should be taken to follow the directions carefully. The Environmental Protection Agency has also classified permethrin as "likely to be carcinogenic to humans" if ingested.



P-menthane-3,8-diol may have some associated health hazards. The Environmental Protection Agency has found that long-term skin exposure produces microscopic kidney lesions as well as skin redness and swelling. Canada's Pest Management Regulatory Agency states that one study found p-menthane-3,8-diol may cause genetic damage.


While the California Department of Pesticide Regulation Report 2007-6 indicates that there was a possible increase in liver tumors and liver necrosis in rat and mice toxicity studies, the Environmental Protection Agency has cleared Metofluthrin as safe, when properly used.



A wide variety of natural extracts and essential oils are used to provide relief from mosquitoes including lemon, eucalyptus, citronella, lemongrass, peppermint, geranium, castor, cinnamon, rosemary, cedar, juniper, soybean, coconut or palmarosa. While these products are generally considered safe and are largely unregulated, allergic reactions can occur. Test these products by applying a small sample to the skin and watch for any reactions prior to extensive use.

Other Ingredients

Some inactive ingredients in repellent formulas including solvents and diluents like isopropyl alcohol also can cause adverse reactions. Children, in particular, are prone to injuries involving swallowing or overexposure. All insect repellents should be kept out of reach of children.



When properly used, repellents can be a very effective means of controlling mosquitoes. These simple rules will help you use them most effectively.

Be sure to follow the directions carefully. Be careful when using aerosol pumps or sprays, especially in enclosed areas. Do not apply repellents to the hands of young children who might put them in their mouths. Also, do not apply repellents under clothing. Wash any clothing that repellents are applied to before wearing them again. Once indoors, wash all treated skin with soap and water.