This story originally ran May 15, 2018, and was updated August 27, 2024.
Your skin is your largest organ, and it deserves protection. When you’re outside for any length of time, you should apply sunscreen to your exposed skin—even on cloudy days and in the winter.
There’s no shortage of available sunscreens to purchase. If you’ve ever been overwhelmed by your choices or aren’t sure which option is best for you and your family, UNC Health dermatologist Shweta Shukla, MD is here to help.
Why is sunscreen important?
The sun produces ultraviolet radiation which affects the skin. UVA rays can penetrate the skin’s upper layer and cause damage under the surface, which leads to wrinkles, sagging and age spots. UVB rays affect the skin’s top layer, causing painful burns and blisters. Both UVA and UVB rays can cause skin cancer.
“Sunscreen protects the skin from UV rays and reduces the risk of skin cancer,” Dr. Shukla says. “It also reduces the risk of sunburns and premature aging of the skin.”
Remember that even a “tan” is damage: When UVA rays penetrate the skin, they begin damaging skin cells, and your cells produce melanin to try to stop that damage. That’s what gives you a darker hue, but the damage to your cells has been done. Tans don’t prevent sunburns or protect against skin cancer.
Sunscreen is not recommended for babies 6 months or younger, but it is necessary for everyone else, regardless of skin color. (Young infants should be kept out of the sun or covered with clothing and hats.)
What’s the difference between physical and chemical sunscreen?
There are two general categories of sunscreen: physical, also referred to as mineral, and chemical.
“Physical or mineral sunscreen sits on the skin and acts like a shield,” Dr. Shukla says. “Chemical sunscreen works like a sponge and absorbs the rays.”
Each sunscreen has different active ingredients. Physical sunscreen uses zinc oxide and titanium dioxide, while chemical sunscreen uses oxybenzone, avobenzone and octisalate. Some hybrid sunscreens contain a mix of both types of ingredients.
Both types of sunscreen are effective at protecting your skin from ultraviolet rays when applied correctly, so the one you choose comes down to personal preference. Chemical sunscreen is usually easier to rub in, whereas mineral sunscreen may leave a white residue and feel heavier. Dr. Shukla says that mineral sunscreen may be better for people with sensitive skin, including children, because titanium dioxide and zinc oxide are less irritating to the skin.
What is SPF and what number should I choose?
Sunscreens come with an SPF number printed on the bottle. SPF, short for sun protection factor, is a measure of how well protected you are from the sun’s UVB rays.
It is not a measure of how long you can safely be in the sun, and the increase in numbers doesn’t correspond to an increased level of protection, meaning that SPF 60 is not twice as protective as SPF 30.
“The American Academy of Dermatology recommends using SPF of at least 30, which will block 97 percent of the sun’s UV rays,” Dr. Shukla says. “A higher SPF may block slightly more rays, but no sunscreen can block 100 percent of the rays. There may only be a marginal effect as you go higher in SPF.”
What kind of sunscreen should I buy?
“Sunscreen should be broad-spectrum, which means it protects from both UVA and UVB rays, have a SPF of at least 30, and be water-resistant,” Dr. Shukla says. “Then it’s really about what works for you. A good sunscreen is the one that you will use.”
That means you have a lot of choices in the sunscreen aisle—lotions, creams, sticks and sprays. Dr. Shukla says all are fine as long as they are applied correctly and consistently.
No sunscreen is waterproof or sweatproof, but a sunscreen deemed “water resistant” by the FDA keeps its effectiveness in water for 40 minutes; “very water resistant” will remain effective for 80 minutes in water.
If you have a skin reaction to a sunscreen, Dr. Shukla recommends talking to a dermatologist. They can evaluate and suggest products that will work better for you.
How do I apply sunscreen? What are some common mistakes?
Sunscreen should be applied to dry skin about 15 minutes before you go outside. It should be applied to all exposed skin, which is where many people make mistakes.
“It’s common to forget the tops of the feet, the neck, the ears and the top of the head,” Dr. Shukla says. “Your lips also need a coverage. There are lip balms with SPF.”
Dr. Shukla says that most people don’t apply enough sunscreen. Adults need about 1 ounce, or a full shot glass, of sunscreen to cover their body. It may be easier to see where you’ve applied sunscreen when you use a gel or lotion; one issue with spray sunscreens is that it may be hard to tell if all skin is covered. If you do use a spray sunscreen, rub it in after you spray to ensure thorough coverage.
People sometimes assume that sunscreen is a one-and-done application, but sunscreen should be reapplied every two hours, or more often if you’re sweating or swimming. Don’t forget your sunscreen at home if you’re on the go, and set a timer on your phone to help you remember to reapply. If you use a moisturizer with SPF on your face and a different sunscreen product for your body, remember to keep both on hand for reapplication.
Some people think they only need sunscreen when it’s sunny, but ultraviolet rays affect our skin on cloudy days too, so apply year-round. Be sure to check any old bottles or tubes of sunscreen in your home—sunscreen does expire.
What else should I do to protect myself from the sun?
Remember, no sunscreen can block all of the sun’s UV rays. It’s important to take additional steps to protect your skin from the sun.
“Try to avoid being outside from 10 a.m. to 2 p.m., when it’s brightest,” Dr. Shukla says. “Stay in the shade as much as possible. Wear long-sleeved shirts and wide-brimmed hats.”
Ultraviolet rays can also damage your eyes and cause cataracts, so wear sunglasses with UV protection.
You could also consider sun protective clothing with an ultraviolet protection factor (UPF) but your exposed skin will still require sunscreen. Check the label of any UPF-rated clothing to see how UPF will be affected by water, washing and wear.
Isn’t it important to get some sun exposure?
You may have heard that it’s important to get sun exposure—without sunscreen—because UVB rays trigger vitamin D production, and vitamin D is critical for bone health. Even so, it’s it’s important not to increase your risk of skin cancer when there are other ways to obtain the nutrient, Dr. Shukla says.
“Using sunscreen may affect your ability to get vitamin D via the skin, but you can get vitamin D through your diet,” she says. “It’s better to protect your skin and discuss your diet and a possible supplement with your doctor.”
Concerned about your skin? Talk to your doctor or a dermatologist. Need a doctor? Find one near you.The post Everything You Need to Know About Sunscreen first appeared on UNC Health Talk.
