These are the most common questions I field regarding sunscreen.

What age can I use sunscreen?

The American Academy of Pediatrics does not recommend the routine use of sunscreen in children younger than 6 months. Prior to 6 months, parents should simply keep a child out of the sun as much as possible (using sun protective clothing, beach umbrellas, etc.). With that said, I always advise my patient’s parents that I would much rather they apply sunscreen to their 4-month-old’s face if adequate shade is not available than risk a sunburn.

What is SPF?

SPF stands for Sun Protection Factor. The SPF is simply a multiplication of the time it would take to burn without sunscreen. So if I am fair-skinned and would burn in 10 minutes of being in the sun, adding SPF 15 would theoretically allow me to stay in the sun for 150 mins (10 mins x 15 SPF) before burning. So, using the same example, if I’m dark skinned and won’t burn for 20 mins of sun exposure, then I could theoretically be in the sun 300 mins with SPF 15 (20 mins x 15 SPF). However, there are lots of caveats to the system. The number is based on a controlled factory setting where a perfect, thick layer is applied and left alone. Uneven application, sweating, rubbing from clothes, water sports/swimming, etc., can all wear off the sunscreen. So you can see how reporting SPF as how long you stay in the sun is not really accurate. My basic rule of thumb: use a high number (the dermatologists say at least SPF 15; as a pediatrician, I like at least SPF 30) and reapply frequently (every 1 ½-2 hours). In case you are curious, the US Food and Drug Administration (FDA) regulates sunscreen products. The official definition (which is basically what I described above) as per the Federal Register 1999: 64: 27666-27963, states that SPF is the dose of Ultraviolet Radiation (UVR) required to produce 1 minimal erythema dose (MED) on protected skin after the application of 2 mg/cm2 of product divided by the UVR required to produce 1 MED on unprotected skin.

What product should I use?

Look for sunscreen with the following features:

  • Is it designed for children?
  • Is waterproof?
  • Does it have a high SPF (greater than 30)?
  • Does sunscreen expire?

Yes. I know it seems crazy, but sunscreen does expire. Like any “drug,” it has an active ingredient that over time loses its potency. Every bottle should have an imprinted date on it (usually on the crimped end/edge). Dates on drugs/products regulated by the FDA have a guaranteed potency to that date given regular/appropriate storage (which is supposedly a cool/dry area). So drugs kept in a moist/hot bathroom medicine cabinet can actually lose potency earlier than the date. It’s not like the drug suddenly stops working the day of the printed expiration date comes around. It’s just a question of how well (if any) will the “drug” or product work after the date. So when you buy sunscreen, look at the date. It may have been sitting on the shelf at the store from the end of last season and you won’t get much use out of it. If you find a new bottle, you may get 2 seasons out of it. Otherwise, you’re stuck buying new each year.