We've said it again and again: Sunscreen is the one beauty staple you should be wearing daily and reapplying regularly. But what do you do if this crucial product that protects you from harmful UV rays leaves your skin red and itchy? Here's what you need to know if you suspect you may have a sunscreen allergy.

What causes sunscreen allergies?

Sunscreen allergies affect only a small percentage of people. A study conducted between 2001 and 2010 found that among 24,000 tested patients, only 1 percent had a sunscreen-related allergy. If you think you fall into that 1 percent, there are two types of sunscreen allergies you should know about, each with their own unique cause.

Contact allergy: This occurs when a chemical in a product triggers a reaction directly on the skin where it's applied. This can occur whether you're outdoors or not, and is the most common type of sunscreen allergy, according to dermatologist Dr Arielle Nagler.

Photoallergy: This occurs when sunlight interacts with a chemical in a product and causes a reaction. Symptoms will only arise where sunscreen was exposed to the sun.

Generally speaking, allergies develop after a first exposure. "In this case, the initial exposure could come from the ingredient being in another product like lip balm, shampoo, or makeup," explains allergist-immunologist Dr Karen Hsu Blatman.

Both active and inactive ingredients in sunscreen can trigger an allergic reaction, so anything from preservatives to fragrance could be the culprit. "There are also a variety of ultraviolet light-blockers that may cause allergic reactions, including oxybenzone, avobenzone, and cinnamates," says dermatologist Dr Joshua Zeichner. "PABA (para-aminobenzoic acid) is a very effective blocker of UVB light, but it's rarely used anymore because of a high risk of allergies."

Are some people more likely to have a sunscreen allergy than others?

People with a history of eczema and other skin reactions are more prone to sunscreen allergy, Dr Nagler explains. Young women may also be more at risk. The study found that people were less likely to have a sunscreen allergy if they were male, had occupational dermatitis, or were older than 40. This could be because women are more prone to using cosmetics that contain sunscreen.

Symptoms of sunscreen allergy

This type of allergy usually manifests as a red, itchy rash with bumps in the area you applied sunscreen. "Usually it is a delayed rash, as if you touched poison ivy," Dr Blatman says. There may also be swelling or fluid-filled blisters.

If you suspect you're having a reaction to sunscreen, wash the product off immediately and avoid using it again, says Dr Zeichner. Schedule an appointment with your dermatologist and bring the sunscreen product with you. "Your dermatologist may discuss with you patch testing, which is a specialised test in the office that can evaluate allergies to specific ingredients," he explains.

How to protect yourself from the sun

Being allergic to sunscreen doesn't mean you're destined to burn to a crisp every beach day and eventually develop skin cancer. To stay sun safe, opt for a physical or mineral sunscreen, which sits on top of the skin, rather than a chemical sunscreen that soaks in. "Physical sunscreens, which contain zinc oxide or titanium dioxide, reflect light and are less known to cause allergic reactions. This is because their ingredients don't penetrate the skin," explains Dr Blatman. Physical sunscreen tends to be more visibly white and gooey because it's not sinking in, but it's less likely to irritate your skin if you have allergies.

Remember that a wide-brimmed hat, sunglasses, and rash vests also go a long way toward protecting your skin from UV light. Combine a few of these accessories with the proper mineral sunscreen, and you'll still be able to enjoy the sun just like everyone else. 

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