Chapter 57: How to Apply Sunscreen, Insect Repellent, and Permethrin

It’s tempting to use a combination sunscreen and insect repellent to make application easy and efficient.

DEET can be applied in a combination product with sunscreen, but there are some concerns and guidelines. Since the sunscreen will probably have to be applied more often, it’s best not to use a combination product, especially on children.

Sunscreens are meant to work below the skin and repellents are designed to be an olfactory (sense of smell) barrier on top of the skin. Most people apply sunscreens more generously since they need to protect all exposed skin.

It’s best to apply the sunscreen first and wait a few minutes before applying the repellent.

Most experts think that insect repellents lower the SPF of sunscreens, so use a sunscreen with a high SPF.

Experts recommend concentrations of 20% to 35% DEET for adults. Higher percentages of DEET don’t give much more protection or last much longer. Since the sunscreen will likely cause the DEET to be absorbed into the skin at more than three times the normal rate, you may want to lean more toward the 20% DEET than the 35%.

Picaridin, or Cutter Advanced, is recognized by the EPA as an effective alternative to DEET. Picaridin’s protection and duration are similar to DEET, and it has some advantages. It is colorless and nearly odorless, with a light, clean feel. It has low toxicity.

So, apply your favorite sunscreen for the conditions, and then wait a few minutes and add your DEET or Cutter Advanced repellent.

For clothing and gear, spray on permethrin, a synthetic chemical that knocks down mosquitoes and other insects such as ticks, flies, and ants. The permethrin doesn’t work on your skin, but it bonds to fabric and works in combination with the insect repellent to give you complete protection.

For more complete information, see our chapter 21 on insect protection.