Is insect repellent safe for my baby?

The verdict

It depends entirely on which country's rules you are following, and the gap is wider than on any other topic covered here.

The UK. UK malaria prevention guidance from the UK Malaria Expert Advisory Group, published on GOV.UK, states that DEET is not recommended for infants below the age of 2 months, and that DEET may be used at a concentration of up to 50% by women who are breastfeeding and for infants and children aged over 2 months. It goes further: DEET is suitable for all individuals over the age of 2 months unless allergic.

Canada. Health Canada's rules are much tighter. For infants younger than 6 months old, do not use an insect repellent containing DEET. Instead, use a mosquito net when babies are outdoors in a crib or stroller. For children aged 6 months to 2 years, the right concentration is up to 10%, and you should not apply the product more than once a day. For children aged 2 to 12 years, up to 10%, applied up to 3 times daily. For adults and children older than 12, up to 30%.

Those are not compatible positions. A four-month-old with repellent on in London is following national guidance. The same child in Toronto is not.

Why the disagreement exists

Both regulators are looking at the same safety data and weighing it against different threats.

The UK guidance is written for travellers, and specifically for travellers going to malaria-endemic countries. When the alternative is a child catching malaria, a repellent with a fifty-year safety record looks like an easy trade. GOV.UK notes that DEET has been in use as an insect repellent for more than 50 years and is reportedly used worldwide by approximately 200 million people each year, that a variety of studies has concluded there is a low risk of adverse effects when applied according to product directions, and that the EPA examined data on seizures potentially related to DEET exposure and concluded the observed incidence of recognised seizures is about one per 100 million users. It adds that there is no current evidence that any group, including pregnant women and small children, is at increased risk from using 50% DEET.

Health Canada is regulating a domestic product for everyday summer use, where the mosquito-borne disease risk is far lower. In that setting there is little to gain from applying a chemical to a young infant's skin, so the precautionary answer wins.

The American position sits between them and is less prescriptive than either. The AAP says that until infants and children are at least 2 years old, their skin may be different than the skin of an older child or adult, so apply DEET sparingly when needed, weighing the risks of exposure to potentially serious illness spread by insects against the possible risk of absorbing chemicals into the body. It adds that parents of newborns and premature infants should be especially cautious. GOV.UK notes that the EPA states DEET is approved for use on children with no age restriction.

What the concentration actually buys you

Higher DEET does not repel more insects. It repels for longer. The AAP gives the numbers: 10% DEET provides protection for about 2 hours, and 30% DEET protects for about 5 hours. A higher concentration works for a longer time, but anything over 50% DEET does not provide longer protection. GOV.UK says the same: there is no further increase in duration of protection beyond a concentration of 50% DEET.

So choose by how long you will be outside, not by how many mosquitoes there are. The AAP's advice is to choose the lowest concentration that provides protection for the time spent outside.

The alternatives, and their own age limits

Picaridin, called icaridin in Canada. The AAP says repellents containing 5% picaridin can protect against mosquitoes and ticks for 3 to 4 hours, and products with 20% picaridin can provide protection for 8 to 12 hours. GOV.UK advises a 20% preparation if a traveller elects to use icaridin. Health Canada is clear that icaridin products should not be used on infants younger than 6 months old.

Oil of lemon eucalyptus and PMD. This one is unanimous, unusually. The AAP, the CDC and Health Canada all say do not use products containing oil of lemon eucalyptus or para-menthane-diol on children younger than 3 years old. The AAP adds that pure oil of lemon eucalyptus products have not been tested for safety as insect repellents and are not registered with the EPA.

Permethrin-treated clothing. Health Canada notes that in Canada, permethrin-treated clothing is not available for children under the age of 16, though adults wearing it may touch or hug young children while avoiding prolonged contact such as carrying a young child who may suckle or chew on the fabric. The CDC advises treating clothing and gear with 0.5% permethrin and never applying permethrin products directly to skin.

Physical protection first, at any age

For a baby under six months this is the whole answer, and it is what Health Canada prescribes in place of DEET.

The CDC's tips for babies and children are: dress your child in clothing that covers arms and legs, and cover strollers and baby carriers with mosquito netting. The AAP says use mosquito netting over baby carriers or strollers in areas where your baby may be exposed to insects. GOV.UK notes that insecticide-treated mosquito nets have become an important and cost-effective method of bite prevention globally, with protective efficacy for travellers estimated at 50%.

How to apply it to a child

The CDC and AAP give the same method. Always follow label instructions. Do not apply repellent to a child's hands, eyes, mouth, cuts or irritated skin. Adults should apply repellent onto their own hands and then apply it to a child's face. Use repellents only on exposed areas of skin, and do not apply on skin under clothing. Wash it off when you come indoors.

Health Canada adds a duration limit that nobody else publishes: for children younger than 12 years old, do not use a DEET product on a daily basis for more than a month.

Sunscreen and repellent together

Apply sunscreen first, repellent second. The CDC, Health Canada and GOV.UK all say this. The AAP advises against combination sunscreen and repellent products, because sunscreen needs to be reapplied every 2 hours and applying a combined product that often may expose your child to too much insect repellent.

Where guidance genuinely differs

Six months versus two months. Health Canada prohibits DEET under six months. GOV.UK permits it from two months. That is a four-month gap in a first year of life, and it is the single largest divergence in this batch.

10% versus 50%. Health Canada caps DEET at 10% for everyone under 12. GOV.UK recommends 50% as the first choice for anyone over two months. The same bottle is standard advice in one country and five times the permitted strength in the other.

Frequency limits exist only in Canada. Once daily from six months to two years, up to three times daily from two to 12, and not daily for more than a month under 12. No UK or US guidance sets application frequency by age.

The US sets no minimum age in regulation. GOV.UK records that the EPA states DEET is approved for use on children with no age restriction, while the AAP asks for sparing use under two years. That is the loosest position of the three.

The reading that satisfies everyone: under six months, netting and clothing only. From six months, the lowest concentration that covers your time outdoors, applied by an adult to exposed skin only, sunscreen first, washed off indoors, and 10% if you are in Canada.