What Dermatologists Actually Want You to Know About Sun Protection

Not all sunscreens are created equal, and the differences matter more than most people realize. Jennifer Sawaya, M.D., a board-certified dermatologist and fellowship-trained cosmetic and laser specialist at the Center for Aesthetic and Laser Medicine in Scottsdale, Arizona, said the first thing to look for is broad-spectrum protection. “You want to find something that is broad spectrum, and that means that it is protective against both UVA as well as UVB rays,” she said. From there, SPF matters, but less than people assume beyond a certain point. “SPF 30 protects about 97% of rays. SPF 50 protects about 98% of rays,” Sawaya said, noting that dermatologists generally recommend SPF 30 or greater, with little marginal benefit above that threshold.

Sawaya also pointed to formulation type as a major consideration. Sunscreens generally fall into two categories: mineral formulas containing zinc oxide or titanium dioxide, which physically deflect UV rays, and chemical formulas, which rely on UV-absorbing filters. Mineral sunscreens tend to be the safer choice for children and for anyone with an impaired skin barrier. “Not only are they great for sun protection, but they’re actually great at restoring your skin barrier,” she said, comparing the effect to zinc oxide-based diaper rash treatments.

For those managing acne, formulation matters more than active ingredient. Joel Spitz, M.D., co-founder and chief medical officer at Honeydew, said the vehicle a sunscreen is mixed into, rather than the UV-filtering ingredient itself, is usually what triggers breakouts. “It’s not the active ingredient that’s causing the problem, it’s what the ingredient sits in that can cause more acne,” Spitz said. He recommends products labeled noncomedogenic or nonacnegenic, pointing to brands like Neutrogena, CeraVe and Cetaphil as reliable options with strong dermatology ties, along with lighter gel or lotion textures over thicker formulas that trap oil and dead skin cells in the pores.

If pushed to pick one type, Spitz said mineral-based sunscreens have a slight edge for acne-prone skin. “The chemical has to get absorbed into your skin, whereas the mineral-based sunscreens sit on the top layer,” he said, which can reduce irritation. Application timing differs too: Chemical sunscreens need about 20 minutes to absorb before sun exposure, while mineral formulas work immediately.

How Much and How Often

Even a well-chosen sunscreen falls short if it isn’t applied correctly. Sawaya said most people significantly underestimate how much product they need. “For an adult body, you want to apply a full 1 ounce. So think of like a shot glass,” she said, with children needing about half that amount, roughly a palm-full. “I’m probably guilty of a little bit of this myself,” she added, describing how difficult it can be to fully cover an active, moving child.

Reapplication matters just as much. The standard guidance is every two hours outdoors under normal conditions, but that window shrinks significantly with water or sweat exposure. “You’re not going to be wrong for reapplying every half an hour, 40 minutes if they’re getting wet,” Sawaya said. She noted that UPF swimwear and rash guards can help close that gap by covering the torso and arms, and recommends treating sunscreen as a daily habit rather than a special occasion. “It’s just like brushing our teeth in the morning,” she said, alongside sun-protective clothing, hats and avoiding peak UV hours between 10 a.m. and 4 p.m.

Spitz offered similar practical reminders: Avoid peak sun hours when possible, wear a wide-brimmed hat, reapply every two hours, and stay skeptical of “water resistant” labeling. "I don’t think the water-resistant label is really holding true to its claim,” he said.

Sunscreen’s Role in Treating Acne Marks and Scarring

Sun protection isn’t just about preventing new damage; it also affects how existing skin issues heal. Spitz said one of the biggest frustrations for acne patients, particularly those with darker skin tones, is the dark marks acne leaves behind. “Sometimes the marks bother patients more than the acne,” he said. Those marks, called post-inflammatory hyperpigmentation, typically take six months to a year to fade, and sun exposure can prolong that timeline by overstimulating the melanocytes already producing excess pigment in the area. “The biggest thing for hyperpigmentation is to wear your sunscreen,” Spitz said.

He drew a distinction between hyperpigmentation and true acne scarring, indented scars like ice-pick or rounded atrophic scars, which sunscreen doesn’t directly treat, though unprotected sun exposure can make such scars more visually noticeable. Spitz also flagged an often-overlooked interaction between sun exposure and common acne medications. Tretinoin, a topical retinoid typically applied at night, is chemically unstable in sunlight. “Sun exposure breaks down the tretinoin, and it doesn’t work as well,” he said. Tretinoin also thins the skin’s outer layer, allowing sunlight to penetrate more deeply toward the melanocytes and increasing both pigmentation risk and inflammation. Isotretinoin, commonly known by the former brand name Accutane, has a similar effect internally. “Dry, irritated skin, either from tretinoin or from Accutane, could make you more sun sensitive,” Spitz said.

Retiring Common Myths

Misconceptions about sun protection remain widespread, even among people who consider themselves sun-safety conscious. Shawn Allen, M.D., a dermatologist practicing in Colorado and a spokesperson for The Skin Cancer Foundation, said a higher SPF number doesn’t mean sunscreen can be reapplied less often. “You want to reapply every two hours regardless of the SPF,” he said, since chemical sunscreens lose potency through a reaction triggered by UV exposure.

Allen also pushed back on the idea that people with darker skin tones don’t need to worry about skin cancer. “People with darker skin tones actually do need to worry about skin cancer,” he said, citing roughly a 1% to 2% risk in Black or African American individuals, 2% to 4% in Asian individuals, and skin cancers accounting for 4% to 5% of all cancers among Hispanic individuals. Melanomas that develop in less-pigmented areas, such as the palms, soles of the feet or under the nails, are often detected later. “Those can be more dangerous, more advanced by the time they get detected,” Allen said.

Clouds and windows offer less protection than most people assume, too. “The clouds will protect about 80% of the UVB coming through,” Allen said, but UVA rays largely pass through unaffected, a pattern that also holds true for car and office windows. A base tan doesn’t offer meaningful protection either. “A tan is actually a sign that you had already received some damage,” he said, since tanning reflects the skin’s own attempt to guard against further harm.

Recognizing Sun Damage Early

Because sun damage is cumulative, its effects often aren’t visible until years after the exposure that caused them. Early signs include freckles, sunspots, uneven pigmentation and a rough or leathery skin texture. More advanced photoaging can appear as fine lines, broken capillaries or actinic keratoses, rough, precancerous patches that should always be evaluated by a dermatologist.

More serious warning signs follow the ABCDE rule commonly used to screen for melanoma: asymmetry, irregular borders, uneven color, a diameter larger than a pencil eraser, and any evolution in size, shape or sensation over time. Allen noted that most skin cancers are highly treatable when caught early. “We have almost a 99% cure rate,” he said, citing a roughly 99% five-year survival rate for melanoma detected before it spreads.