Sun protection when your medicine makes skin sun-sensitive

This page is for people taking medicines that can make skin react to sunlight. It explains the two kinds of reaction, FDA's sun protection checklist, and what to do if a reaction happens.

Some medicines change how your skin behaves in sunlight. FDA calls this photosensitivity. It defines it as a chemically induced change in the skin that makes a person sensitive to sunlight. It can cause sunburn-like symptoms, a rash, or other unwanted side effects.

FDA describes it as a reaction linked to the medicine and light.

FDA separates photosensitivity into two kinds. The difference clears up a lot of confusion.

Phototoxicity is described as an irritation of the skin that can occur within a few hours of sun exposure. This is the one that looks and feels like an unexpectedly severe sunburn.

Photoallergy is described as an allergic reaction of the skin. It may not occur until several days after sun exposure. That delay is why people often fail to connect a rash on Wednesday with an afternoon outdoors on Sunday.

If a reaction shows up days later, the sun can still be the cause.

FDA's protection advice is a short set of steps. They work together, so use them all rather than picking one.

• Seek shade. FDA says to seek shade especially between 10 a.m. and 2 p.m. It notes that some groups suggest protection as late as 4 p.m.
• Cover up. FDA names long-sleeved shirts and pants.
• Protect your eyes and face. Sunglasses and broad-brimmed hats are named specifically.
• Use sunscreen. FDA recommends broad-spectrum coverage with an SPF value of 30 or higher.
• Reapply it. FDA says to apply sunscreen as directed and as needed based on physical activity, especially after swimming or sweating.

FDA names a wide range of medicine types that may cause photosensitivity. Its list includes:

• Antibiotics and antifungals
• Antihistamines
• Cholesterol-lowering drugs
• Diuretics (water pills)
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Oral contraceptives and estrogens
• Phenothiazines
• Psoralens
• Retinoids
• Sulfonamides
• Sulfonylureas (for type 2 diabetes)
• Alpha-hydroxy acids (in cosmetics)

Several of those turn up in the medicine cabinet of someone going through cancer treatment, often for reasons unrelated to the cancer. An antibiotic for an infection or an anti-inflammatory for pain can be enough.

The practical step is to ask a pharmacist to look at your full list, including the things you buy yourself. That is a short conversation, and it beats guessing.

Sun exposure adds up in small pieces: waiting for a ride, walking from the parking lot to the clinic, sitting in a garden for twenty minutes.

A few habits cover most of it:

• Keep a hat and sunglasses where you keep your keys
• Choose the shaded side of the street by default
• Put sunscreen on skin that clothing does not cover
• Reapply after any activity that involves sweating

FDA also says reactions can come from artificial light, such as a tanning booth, not only sunlight.

FDA advises talking with your health care professional or pharmacist if you have concerns about a medicine and sun exposure. Tell whoever prescribed the medicine if your skin reacts. Do not stop a medicine on your own.

Describe when you were in the sun, how long for, and when the skin changed. Because photoallergy can lag by several days, that timeline is useful information, not a minor detail.