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Arusha Campbell-Chambers: Insect repellents: What you need to know

Published:Wednesday | February 3, 2016 | 12:00 AMArusha Campbell-Chambers

There has been an increase in the use of insect repellents due to the threat of viral infections transmitted by mosquitoes. Here are some guidelines derived from regarding the different types of insect repellents.

1. DEET is believed to be the most effective insect repellent. Studies have shown that 23.8 per cent DEET gives about five hours protection from mosquitoes. The American Academy of Pediatrics suggests that concentrations of 10 per cent to 30 per cent DEET can safely be used in children over two months. These concentrations should also be effective in adults to keep most mosquitoes from the skin. Concentrations over 50 per cent DEET do not give much higher protection.

2. In children between the ages of two months to two years, the lowest concentrations of DEET should be used ideally once daily. It can be used up to three times a day in children over two years of age. Avoid applying the product to the hands and eyes. Avoid applying to cuts, wounds, infected or irritated skin. DEET can damage synthetic fabrics and plastics.

3. DEET is believed to be safe to be used in women who are pregnant or breastfeeding.

4. There have been concerns about allergic or irritant skin reactions to DEET and the safety of this ingredient in general. If you suspect a reaction to the repellent, stop using it, wash it off and visit your doctor. Studies have not proven that DEET causes cancer.

5. DEET should be used on areas of skin that are not covered by clothing. Avoid using products that combine sunscreen and DEET as the effectiveness of the sunscreen can be reduced by DEET. Also, sunscreen should ideally be reapplied to the skin every two hours, whereas DEET should not be used that often. DEET can be applied 20 to 30 minutes after applying sunscreen.

6. Permethrin is an insecticide that can be applied to clothing and mosquito netting. Some clothes can be bought that already have permethrin in them. Permethrin may keep working even after clothes have been washed.

7. Picardin spray may be as effective as DEET as an insect repellent. It is less irritating than DEET and is odourless and non-greasy. It should not be used on infants younger than two months.

8. Lemon eucalyptus oil and soybean oil have insect repellent properties similar to low concentrations of DEET. Lemon eucalyptus oil can provide up to two hours of protection but should be avoided in children less than three years old. It can be applied up to twice daily. Two per cent soybean oil can be used in infants and children and provides up to four hours protection.

9. Other plant oils like citronella and lavender are not as effective as DEET and give about 20 minutes protection. They can be reapplied frequently to increase their effectiveness.

10. While insect repellents come in many different forms like electronic devices, citronella candles, geranium house plants, and mosquito traps, they are not believed to provide adequate protection against mosquito bites.

-- Dr Arusha Campbell-Chambers is a dermatologist and founder of Dermatology Solutions Skin Clinics & Medi-Spas; email: