This summer, while you’re having fun in the sun, keep in mind that three conditions linked to sun exposure — drug-induced sun sensitivity, sun allergy, and sun-induced eczema — can seriously damage older skin.

Drug-induced sun sensitivity, also known as phototoxicity, most often occurs when the sun’s ultraviolet (UV) rays interact with a medication you’re taking and cause an almost immediate reaction on your skin. (See table below for a list of medications likely to cause skin reactions.)

A sun allergy, often called a photoallergy, comes on more slowly but can also be dangerous.

This type of sun sensitivity usually happens when UV rays convert a chemical, such as a fragrance on your skin, into a substance that your immune system decides to attack.The result is an itchy, red rash that can take several days to go away.

Finally, sun-induced eczema occurs when your entire immune system goes haywire, causing itchy, red skin or, in severe cases, blisters.

Dermatologists think long-term, intense sun exposure may alter our skin in such a way that our immune system no longer recognizes it as our own. The condition tends to be more common in older men with a history of working outdoors, though it has also been seen in women who love to sunbathe.