A Dermatologist’s Guide to Sunscreen

John Fournier answers everyone's most common questions about sun protection.


Photo via iStock.com/boophotography

We all know we should be applying sunscreen daily. But somehow, no matter how many times we hear it, many of us continue to ignore or forget the nuts and bolts of sun protection.

With Boston heating up again, we asked John Fournier, a dermatologist at Boston Dermatology Group, to answer a few common questions about effectively using sunscreen, so you can finally master summer skincare.

Which SPF should I use?

Fournier suggests SPF 30 or higher. Make sure you choose a broad spectrum product, which means the formula protects against both UVA and UVB rays.

When should I be using sunscreen?

The short answer? Any time you step outside. “Sunscreen should be used whenever there is any sun exposure, as all exposure to UV rays damages the skin,” Fournier says. He suggests minimizing sun exposure during peak UV hours, from 10 a.m. to 3 p.m., and applying a broad spectrum moisturizer in the morning.

Who is most susceptible to sun-related skin damage?

While everyone should be using sunscreen, Fournier says those with acne and blemish-prone skin should take extra caution. “The sun’s rays can cause a brown or red spot to persist for months after a pimple resolves,” he says. Certain common medications, such as those that contain retinol or glycolic acid, may also increase risk of sun damage.

I’m using sunscreen. Why am I still getting burned?

Fournier notes that many people simply don’t apply a thick enough layer of sunscreen. “On average, most individuals typically only use between 25 percent and 50 percent of the necessary volume to adequately protect the skin,” he says. The American Academy of Dermatology suggests using an ounce—or enough to fill a shot glass—all over the body. Don’t forget to screen up every two hours, either. “I tell patients that if they are going to the beach for the day, they should expect to put on sunscreen three times,” Fournier says.

How do I care for my skin after too much sun exposure?

Take a cool shower, then apply a moisturizer to keep the skin hydrated, Fournier says. Taking an anti-inflammatory medication, like ibuprofen, may also help reduce swelling.