Practice Therapeutics

Mosquito repellents for travellers

BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h99 (Published 19 February 2015) Cite this as: BMJ 2015;350:h99
  1. Nina M Stanczyk, research fellow1,
  2. Ron H Behrens, senior lecturer12,
  3. Vanessa Chen-Hussey, research scientist and clinical trials manager13,
  4. Sophie A Stewart, senior research scientist and clinical trials coordinator3,
  5. James G Logan, senior lecturer13
  1. 1Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
  2. 2Hospital for Tropical Diseases, London, UK
  3. 3Arthropod Control Product Test Centre, London School of Hygiene and Tropical Medicine, London, UK
  1. Correspondence to: James G Logan James.Logan{at}lshtm.ac.uk
  • Accepted 23 December 2014

The bottom line

  • Always recommend a topically applied repellent with a proven active ingredient such as DEET (20-50%), PMD (30%), or Icaridin (20-50%). IR3535 (20%) is recommended only for areas that are not malaria endemic

  • Reapply repellents at least every six to eight hours if using DEET or IR3535, or every four to six hours for PMD and Icaridin, and sooner if they wear off while swimming or sweating in warm weather

  • DEET can be used on children over 8 weeks old, PMD on children over 3 years

  • DEET is safe for use from the second trimester onwards and while breast feeding

Case scenario

A pregnant woman visits you as her general practitioner (GP) because she and her children will be visiting a country with mosquito borne disease. You recommend using repellents to protect against mosquitoes, as well as vaccinations and other relevant disease prevention measures. She asks which repellents would be best.

What are the active ingredients?

The key factors to consider when choosing a repellent are the active chemical ingredients and the strength (concentration (%) of active ingredient) because these influence the efficacy and duration of protection.1 2 There are four active ingredients with sufficient published scientific evidence to warrant recommendation. Repellents are useful in areas of low risk of mosquito borne disease to prevent nuisance biting (which may lead to problems such as allergies) and are essential in moderate to high risk areas (figure) to prevent disease transmission (such as malaria and dengue fever) through bites. Repellents work on mosquitoes by directly stimulating avoidance behaviour or by blocking the mosquito’s receptors for attractive odours, not though toxicity.3

Areas of low, moderate, and high risk of mosquito borne disease worldwide

  • DEET—N,N-Diethyl-meta-toluamide has been in use since 1946 and is the “gold standard” repellent recommended by the World Health Organization Pesticide Evaluation …

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