Sunscreen can be confusing. There are many different SPFs, UVA and UVB rays, expiration dates and brands. It quickly becomes overwhelming. Here is some information to keep your skin healthy, year-round.

A higher-level SPF means I can apply it less often.

FICTION. Higher sun protection factor (SPF) does not mean you can apply it less. Both sweating and swimming wash off sunblock. If you’re wondering what to look for in sunscreen, I recommend using a minimum of SPF 30. There is some controversy over SPF numbers. Some researchers suggested anything higher than SPF 50 does not give added benefit.But, a recent study suggests for people with a lot of exposure and risk of burning, a higher SPF can help. No matter what the SPF number, sunscreen should be reapplied every two hours while outdoors. It’s also a good idea to add a face lotion with SPF for year-round use.

UVA and UVB rays are all the same.

FICTION. The SPF only tells you how much UVB protection you are receiving. UVA, although it is less intense outdoors, is just as strong at 8 a.m. as it is at noon. It is present year-round and goes through window glass. UVA also goes deeper in your skin than UVB. Both cause skin cancer, but UVA also causes wrinkles because it damages the collagen and elastic tissue in the skin. You’ll want a broad-spectrum sunscreen with both UVA and UVB protection.

All sunblock is the same.

FICTION. Sunblock can work with physical or chemical blockers. Physical blockers sit on top of the skin and don’t allow the UVA and UVB rays from the sun to get into the skin. Because physical blockers don’t enter the skin, they cannot cause allergic reactions, and they don’t irritate the skin or eye. These sunscreens include active mineral ingredients like zinc oxide and titanium dioxide. Because the minerals are not reactive with the skin, they are often used alone in “sensitive skin” sunscreen and children’s sunblock. However, since it sits on top of the skin, it wipes off more easily. With young children, you can spread it on their skin and not completely rub it in, which allows you to make sure there is enough there to protect them and lets you know if they wipe off an area. The mineral blockers should make up at least 5 percent of the sunblock. If it has both types (zinc oxide and titanium dioxide), just add up the percentages.

Chemical blockers soak into your skin cells. They work to inactivate the UV rays entering the skin, turning it from electromagnetic waves into heat, which is not harmful to the skin. These sunscreens should contain a minimum of 2 percent avobenzone and a minimum of 3.6 percent octocrylene to get complete UVA protection. You’ll want to take note that the higher the SPF, the more chemicals get into your skin, giving you a chance to develop allergies or irritation from them. Allergies to sunblock often look like a bad sunburn. Chemical blockers must be put on at least 20 minutes before going outside to allow it to soak in.

Some chemicals in sunscreen seep into the blood stream.

FACT. The chemicals in the chemical blockers seep into the blood stream, they don’t just sit on top. A 2019 study by the FDA found the levels of chemicals in the bloodstream are unacceptable and toxic. Of the 16 currently marketed active ingredients, the FDA considers two (zinc oxide and titanium dioxide) to be safe and effective. Two others are not considered safe and effective (PABA and trolamine salicylate). The FDA says there isn’t enough information to decide about the 12 other ingredients just yet, and they are recommending further study of these ingredients.

Babies shouldn’t wear sunscreen until they are six months old.

FACT. Babies shouldn’t wear sunblock of any kind until they are six months old. After that, they should not use any products with chemical blockers in them. The only sunscreen safe for young children are zinc oxide and titanium dioxide, which are physical blockers. Babies have fewer protective dead skin cell layers on the outside of their skin. This is what prevents things on the outside from getting in through their skin. It’s a good idea to keep babies covered until they are a year old. Shade trees can help a little, but beware, if the sunlight under the tree is dappled (shows little flecks of light) then it is only giving partial protection. It’s a good idea to add an umbrella or other shade structure to protect babies.

People with dark skin do not need sunblock.

FICTION. Everyone needs sunblock. People with dark skin have some natural protection from the sun, but they can still sunburn, get wrinkles and skin cancer. Even if your skin is very dark, you should use a sun blocking face lotion to protect your face every day, year-round.

You can still get cancer if you use sunscreen.

FACT. Using sunscreen is something that should be a life-long habit to try to prevent skin cancer, but it’s not a 100 percent guarantee. I have seen basal cell carcinoma (the most common skin cancer) on completely non-sun exposed body areas. I’ve also seen malignant melanoma (a potentially deadly skin cancer, which is becoming more common every year) on areas normally covered with clothes or inside the mouth or eyes. Parents should start using sunscreen on children at an early age, so it’s a learned habit as they get older. Skin cancer is from an accumulation of sun exposure, not from a single episode of sunburn, however, a severe, blistering sunburn doubles your risk of skin cancer. Your DNA in your skin cells develops breaks from UV exposure, and there are repair mechanisms which fix most of them. But, you gradually collect more and more abnormalities until the cells become cancerous. If your immune system isn’t functioning properly and doesn’t get rid of this cancerous cell, then it grows and becomes visible as skin cancer.

Sunscreen will prevent the body from absorbing Vitamin D.

FICTION. Vitamin D isn’t absorbed from the sun. It is made by the body and requires UV light to trigger the reaction in the body that creates the vitamin D. You only need 10-15 minutes of direct sunlight to reap the benefits. So, while sunscreen can block the creation of vitamin D by the body, you still shouldn’t go outdoors without it, especially if you’re going to be out more than about 10 minutes. Practically speaking, if you’re enjoying the pool all day your sunscreen will wear off a bit at some point, allowing enough UV rays in to provide the vitamin D boost. Instead of more time in the sun, consider eating more foods rich in vitamin D, such as dairy products, or add a supplement.

Sunscreen doesn’t expire.

FICTION. Sunscreen does expire, and it can break down if you keep it in a hot car or golf bag. The expiration date does not mean you have to immediately throw the sunblock out. But, you should be putting it on your list of things to get. I suggest using a marker to write the date you open a new tube or bottle. It’s a good idea to toss it after about a year, even if it hasn’t expired. If the product starts to separate and form a clear, oily layer, throw it out. It is no longer able to give you predictable protection.

Dr. Carey Bligard is a dermatologist at UnityPoint Clinic.