Q: I have to use insect repellent every time I go outside. When I also need sunscreen, which goes on first?
A: This straightforward question has no simple answer. The Centers for Disease Control and Prevention recommend that “Sunscreens should be applied to the skin before insect repellents.”
In the next sentence, however, the CDC advises travelers not to use combination products containing both repellents and sunscreens. It points out that “DEET-containing insect repellents may decrease the effectiveness of sunscreens and sunscreens may increase absorption of DEET through the skin.”
We also discovered research demonstrating that DEET and the sunscreen ingredient oxybenzone (benzophenone-3) mutually increased skin absorption (Toxicology and Applied Pharmacology, Sept. 1, 2007). Since oxybenzone has estrogenic activity, increased absorption is not desirable. If you use a sunscreen that relies on zinc oxide or titanium dioxide, this should not be a concern.
For more information on sunscreen safety, we are sending you our new Guide to Skin Care and Treatment. To get a copy, send $3 in check or money order with a long (No. 10), stamped (61 cents), self-addressed envelope to: Graedons’ People’s Pharmacy, No. S-28, P.O. Box 52027, Durham, NC 27717-2027. It also can be downloaded for $2 from our Web site.
Joe Graedon is a pharmacologist and Teresa Graedon is an expert in medical anthropology and nutrition. They can be reached at email@example.com.