Phil asks…Does using facial oils, from certain brands or in general, under a sunscreen affect how good it works? My skin loves certain oils and in spring/summer I use them during the day underneath my sunscreen. I was wondering if it affected the spf, how good it protects, does the oil dissolve some of the protection of it’s a chemical one?
There is cause for concern because it is well documented that certain ingredients can interact with sunscreens. Sometimes this interaction is good, sometimes it’s not so good. For example, a chemical known as Mexoryl SX can improve SPF by reducing the photo degradation of certain UV absorbers like Parsol 1789. Iron chelators like vitamin C and E can also slow the breakdown of sunscreens. On the other hand, care must be taken when mixing sunscreens with insect repellants because of interaction with DEET (the stuff that repels the bugs) because skin penetration is increased.
So, it’s best not to mix sunscreens and other products. As SkinDoc pointed out in our earlier post on the right way to apply sunscreen, the best thing approach is to wait 10 or 15 minutes between application of prodcuts. If you apply an oil to the skin at the same time as the sunscreen you are essentially diluting the sunscreen and it won’t be as effective. Of course no matter what technique you use, the key message here is to wear sunscreen!