Some sunscreen ingredients can cause allergies

It's summer and doctors say that everyone should use sunscreen as a first defense against the powerful rays that can cause sunburns and skin cancer. But what if the very product meant to protect you is causing a skin reaction?

"Many patients come into my allergy practice and they have rashes after using products, sunscreen," Dr. Clifford Bassett, the medical director of Allergy and Asthma Care of New York, told "CBS This Morning."

Discovering which products to avoid and which to apply can keep skin healthy in the sun. People with sensitive or allergy-prone skin should monitor how skin reacts after using sunscreen. Signs that a product may be irritating the skin generally don't appear immediately, they can take up to a few days to emerge.

Contact dermatitis is the most common problem, including rash, itchy skin, blisters or swelling where sunscreen was applied.

"If you have a rash after using sunscreen or using a product in the sun, see a dermatologist or an allergist for patch testing. We can pinpoint very quickly what the problem is, whether it's the sunscreen agent, preservative or fragrance," Bassett said.

Sunscreen can work in two different ways: by physically blocking or diffusing the UV rays with zinc oxide or titanium dioxide creams, or through chemicals like benzophenone that absorb and convert the UV rays so they cause less harm. Allergies to chemical sunscreens are more common, though either could be the culprit.

Those who are sensitive to one kind of sunscreen can generally find an alternative that does not contain those ingredients. The American Academy of Dermatology stresses that the particular kind of sunscreen is not important, as long as the product is pleasant to use and meets personal preferences so it will be used often.

Anyone who's had previous skin damage or eczema may have a greater risk for sunscreen allergies, as well as those who use sunscreen often in their daily routines, like outdoor workers or women who use skin care products containing sunscreens.

Other allergic reactions can happen when skin is exposed to fruit acids like lemon or lime juice before sun exposure.

The AAD recommendations for skin care in the sun can not only reduce the risk of skin cancer, signs of aging and sunburn, but also reduce the risk for allergies that can worsen with excess sun exposure:

• Use a sunscreen with SPF between 30 and 50, even on cloudy days
• Apply one ounce for the whole body, a shot-glass size amount
• Reapply every two hours or after swimming, including on the back
• Minimize time in the sun between peak hours of 10 a.m. to 2 p.m.
• Wear clothes that minimize exposure: dark colors that deflect light, tightly woven fabrics, special UV-protective clothing