Q. When should I apply insect repellent on my baby?

Apply it when your baby (of any age) is hanging out in the great outdoors, especially at dawn or dusk in the summer months.

Mosquitoes and ticks are known carriers of illness. The most notable diseases in the United States spread by these bugs are West Nile Virus (mosquitoes) and Lyme Disease (deer ticks). The safest option to avoid mosquitoes is to stay inside at dawn and at dusk, when they are out in greatest numbers. If you go out and about, have your baby wear light colored clothing, long sleeves, and long pants. And you can get insect netting to cover little ones who are just sitting in their infant carriers or strollers.

As far as insect repellents go, the most effective products contain DEET, picaridin (sold as Cutter Advanced or Off Skintastic), or Oil of Lemon Eucalyptus. But the age of your child limits your options. Picaridin based products are the only ones approved for use in babies from birth to two months of age. DEET based products are considered safe for babies over two months of age. And Oil of Lemon Eucalyptus is only recommended for kids over three years of age (because even small doses in young children have led to serious side effects—like coma and seizures).

Many parents want to avoid using harsh chemicals on their child’s skin and have turned to citronella-based repellents. However, products containing citronella repel mosquitoes for a mere 9.6 minutes, while 23% DEET will repel mosquitoes for five hours. (Fradin) Picaridin is the most effective non-DEET alternative for kids zero to age 3.

The problem with DEET is that it can be absorbed into the body via the skin and cause “neurotoxic effects” like dizziness (and rare, more serious adverse effects in massive doses). Therefore, you should wash the DEET repellent off once returning indoors. Here are some additional safety tips for using insect repellents on your baby: (Wall Street Journal)

1. Young children should not apply repellent themselves— that’s mom and dad’s job.

2. Don’t apply repellent under clothing or to wounds. It goes on exposed skin—yes, that means ALL exposed skin areas, not just the arms or legs.

3. Don’t put any repellent near children’s mouths or eyes— and avoid getting it on their hands.

4. Insect repellents come in several forms—the liquids, sprays, washcloths, and lotions are effective. Exception: The DEET wristbands don’t work.

5. When you come back inside, WASH your baby’s skin.

6. DEET products with a concentration of 30% are as safe as those with 10%. 30% DEET lasts for five hours, 10% just two hours.

7. How much DEET should you use? That depends on how long you plan to be outdoors—10% is fine for less than two hours, etc.

8. DEET should only be applied once a day. Picaridin based products should be re-applied every 3-4 hours.