Are mosquito repellents with DEET safe for kids?

Dengue is why this question matters here rather than being an academic worry about chemicals. Aedes mosquitoes bite in the daytime, and they breed in a bottle cap of water on a corridor ledge.

DEET is considered safe for children over 2 months at concentrations of 10 to 30 per cent, which is the American Academy of Pediatrics position. Apply it to exposed skin and over clothing, never underneath. Keep it off hands, eyes and mouth, and wash it off at the end of the day.

What does DEET do, and what does it not do?

DEET, short for diethyltoluamide, does not kill mosquitoes. It interferes with the way they find you, so a mosquito that would have landed on your child’s calf flies past instead.

It has been in civilian use since the 1950s and is one of the most studied repellent ingredients in existence. The CDC lists it among the active ingredients registered with the US Environmental Protection Agency for skin, alongside picaridin, IR3535, oil of lemon eucalyptus and its synthesised equivalent PMD, and 2-undecanone.

People sometimes confuse DEET with DDT, which is a different chemical altogether. DDT is an insecticide, it persists in the environment, and it was banned in many countries decades ago. DEET is a repellent that washes off with soap.

Is DEET safe for children?

Over 2 months of age, yes. The American Academy of Pediatrics advises against DEET-containing repellents on infants younger than 2 months and regards 10 to 30 per cent as both effective and safe for older children.

Reactions do happen. Skin irritation and redness are the common ones, usually where a product has been left on for a long stretch or applied to broken skin. Serious effects reported in the literature involve swallowing repellent or applying very heavy amounts repeatedly, which is a different scenario from a thin coat before a walk to the playground.

Weigh it against what a bite can do here. Dengue is endemic in Singapore and a child cannot be reasoned out of scratching, so bites turn into broken skin and sometimes into infection. Our guide to common baby rashes helps sort an infected bite from the other things that look like one.

Which concentration should you buy?

Read the percentage on the back, because the words on the front tell you very little. A higher concentration buys time rather than strength, which the American Academy of Pediatrics states directly.

Pick the lowest concentration that covers the time you will actually be outside. Under 2 months, use no repellent at all and rely on a net over the stroller.

How should you apply it to a child?

Spray your own hands first, then rub it on. That keeps the aerosol out of your child’s face and lets you feel how much is going on.

Cover the exposed skin and the outside of clothing, and leave the skin under clothes alone, because DEET trapped against covered skin absorbs more and does no repelling. Skip the hands, which go straight into the mouth. Keep it clear of the eyes, lips, cuts and any patch of eczema.

One application a day is usually the whole job. Wash it off with soap and water when you come home, and wash the clothes it went onto before they are worn again. Ankles, the backs of knees and the hairline behind the ears are the spots everyone forgets.

What should you avoid doing?

Combined sunscreen-and-repellent products are the big one. Sunscreen needs reapplying every couple of hours and repellent does not, so a two-in-one bottle pushes far more DEET onto the skin than anyone intended. Buy them separately, sunscreen first, repellent on top once it has sunk in. If your afternoon involves both, our notes on baby sunburn cover the other half.

Do not use oil of lemon eucalyptus or PMD on a child under 3, which is the CDC’s advice. Do not spray near food or inside an enclosed car. Do not count on a scented candle or a wristband to protect a child in a dengue cluster, because neither covers skin.

A bottle with no named active ingredient and no concentration has told you nothing at all. If your child reacts to any repellent, wash it off with soap and water, stop using it, and take the bottle with you to the doctor.

Do the natural alternatives work?

Some, partly, and for less time. Citronella and lavender oils do repel mosquitoes for a short while before they evaporate, and neither appears on the CDC’s list of recommended active ingredients.

Oil of lemon eucalyptus is the plant-derived option that does hold up, and it comes with the under-3 restriction above. That restriction matters, because the children most often handed a natural repellent are exactly the ones too young for it.

Physical barriers carry no such caveats. Netting over the stroller and cot, long sleeves and long trousers in light fabric, closed windows with the aircon on, mesh screens, and a standing fan pointed low all help, since Aedes mosquitoes are weak fliers.

Why does this matter more in Singapore?

Because the mosquito that carries dengue lives in the same block you do. Aedes aegypti breeds in clean standing water in small containers, bites during the day with peaks in the early morning and late afternoon, and rarely travels far from where it hatched.

The National Environment Agency publishes a dengue cluster map and posts coloured banners at affected blocks, so you can find out whether your estate is in an active cluster today. If it is, use repellent indoors as well as out, and keep the netting on the cot during naps. Learn the warning signs too, because dengue fever symptoms in a small child are easy to mistake for an ordinary fever.

Then run the Mozzie Wipeout check once a week, which takes about ten minutes. Change the water in vases and flower pots. Turn over any pail, basin or bucket. Tip out the saucers under potted plants, loosen hardened soil so water cannot pool, and clear the roof gutter or balcony drain. A single blocked drain on a corridor can breed mosquitoes for the whole floor. Keeping the home clear of other pests helps too, and how to protect your baby from germs covers the rest of that routine.

Where do you buy it here?

Guardian, Watsons and Unity all carry repellents, and Unity counters sit inside many FairPrice stores, which makes it an easy addition to the weekly shop. Supermarkets and the larger convenience chains stock the common brands as well.

Buy a small bottle of a named active ingredient at a stated percentage, and check the expiry. Travel-sized sprays are worth keeping in the diaper bag for East Coast Park, the Botanic Gardens and anywhere with standing water nearby, which in this city is most places with trees.

Watch what happens on your own child after the first use. A small patch on the inner forearm, left for a few hours before you cover a whole pair of legs, tells you whether their skin objects before you find out the hard way at a picnic.