While sunshine can feel good on your skin, overexposure to harmful rays definitely won’t.

Make sure you know how to keep your skin protected while enjoying the warming weather. Here’s some guidance:

Who should use a sunscreen?

Everyone over 6 months of age should use sunscreen to avoid premature wrinkling of the skin and age spots. Cumulative exposure to sunlight also increases your risk of skin cancer. It has been estimated that one in five people will develop a skin cancer in their lifetime.

Can I use sunscreen on an infant?

It is not recommended for children under 6 months of age. Infants should be kept in the shade, and when in the sun should wear protective clothing with long sleeves, pants and a wide-brimmed hat.

What is the best sunscreen to use?

Look for a sun protection factor (SPF) of 30 or higher. A 30 SPF blocks about 97% of the sun’s harmful burning rays (UVB). Look for products labeled “broad spectrum,” which helps to block both the UVB shorter wavelengths of light that cause sunburn, as well as UVA rays, longer wavelengths of light that penetrate deeper into the skin and contribute to aging of the skin and wrinkling. Over time, overexposure to both UVB and UVA can increase an individual’s skin cancer risk.

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Also, look for a sunscreen label that says “water resistant” and indicates how long it works. Even a very good water-resistant sunscreen can be effective for up to 80 minutes, and then needs to be reapplied.

Ultimately, the best sunscreen for you is the one that you will consistently use.

How much sunscreen should I use?

Approximately one ounce of sunscreen (enough to fill a shot glass) would be needed to cover an adult’s entire body. Not using enough sunscreen will provide less than the SPF stated on the product’s label. And don’t forget to protect your lips, which are also prone to skin cancer. Use a lip product with an SPF of at least 30.

How often should I use sunscreen?

Sunscreen should be used every day on any skin that is exposed to the sun, even on overcast days. UVA rays can also penetrate window glass. I see more skin cancers and precancers on the left side of the face and hand than on the right side, which is likely due to sun exposure through the car window while driving.

You should apply sunscreen 15 minutes before sun exposure, and then reapply every two hours, or after swimming or sweating. Sunlight is reflected off sand, snow and water, so be extra cautious when boating, fishing, or swimming outdoors or at a beach. I tell golfers to reapply their sunscreen when they make the turn at the ninth hole.

What is the best sunscreen to use for sensitive skin?

Look for products with zinc oxide and/or titanium dioxide, which are physical blockers and act like shields by deflecting the sun’s harmful rays.

Which forms of sunscreen are best?

I like stick sunscreens, especially for the face, because they won’t irritate your eyes when you perspire. I also find that kids like the stick sunscreens, as it doesn’t make their hands greasy.

I recommend avoiding spray sunscreens, because it’s easy to miss spots on the skin. Also, they shouldn’t be used near the face to avoid inhaling them. Sunscreen sprays are flammable, and burns requiring hospitalization have been reported as a result of their use.

Creams are best for dry skin, while gel sunscreens are useful on hairy areas, like a man’s chest. For acne-prone individuals, look for the word “noncomedogenic” on the label.

I have a tan. Do I still need sunscreen?

A tan is your body’s reaction to injury from sunlight. Tanned skin does not take the place of sunscreen. In fact, you should avoid tanning as it increases your skin cancer risk and ages your skin. If you want a tan look, use a self-tanning cream.

How else can I protect myself from the sun in addition to using sunscreen?

Look for clothing with an ultraviolet protection factor (UPF) label of 50. UPF indicates how much of the sun’s ultraviolet light will penetrate the fabric and reach the skin. Sun-protective clothing is useful in covering large areas of skin. Rash guard shirts are very effective, while wide-brimmed hats add extra protection.

And don’t forget about eye protection. Wear sunglasses labeled UV400, which means that the lens will block 99% to 100% of UVA and UVB rays. This will help protect your eyes and may lessen your risk for cataract formation.

Jeffrey Pollock, MD, FAAD, FACP, is a dermatologist affiliated with Nazareth Hospital in Philadelphia.