Photosensitizing Medications: Sun Reactions and What to Do

Photosensitizing medications make your skin react to sunlight more easily. You burn faster than usual, or you get an itchy rash or blisters on skin the sun reached. Common ones include some antibiotics such as doxycycline, ketoprofen gel, water tablets such as hydrochlorothiazide, amiodarone and isotretinoin. This guide is by Dr. Pedro Yelamo Vera, a GP licensed in Spain (Colegiado No. 484814280).

What are photosensitizing medications?

They are medicines that cause a skin reaction when sunlight hits the skin. Doctors call this photosensitivity. It is mostly caused by UVA light, which still reaches you on cloudy days. The MSD Manual describes two kinds:

• Phototoxic reaction: the most common kind. It shows up within hours and looks like a severe sunburn, only on skin that was in the sun.
• Photoallergic reaction: an allergy. It shows up a day or more later as an itchy, bumpy or eczema-like rash, and it can spread to covered skin.

In Spain the leaflet word is fotosensibilidad. You may also hear medicamentos fotosensibles, but pharmacists use that term for medicines that spoil in light and must stay in their box. That has nothing to do with your skin.

Which medicines cause sun sensitivity?

The list is long. These are the groups you are most likely to meet in Spain:

• Antibiotics: tetracyclines such as doxycycline, quinolones such as ciprofloxacin and levofloxacin, and sulfa drugs such as co-trimoxazole. Read more about Septrin (co-trimoxazole).
• Anti-inflammatory painkillers: ketoprofen gel is the best known. Others, such as ibuprofen and piroxicam, can also do it.
• Water tablets and blood pressure medicines: hydrochlorothiazide and other thiazides, and furosemide.
• Heart medicine: amiodarone. Over time it can also turn sun-exposed skin a blue-grey colour.
• Acne treatments: isotretinoin and retinoid creams. See our guide to isotretinoin in Spain.
• Others: some antifungals (voriconazole), some antipsychotics, methotrexate and St John's wort.

Some skin products with alpha-hydroxy acids, and some perfumes, do the same. To check your medicine, look for fotosensibilidad in the Spanish leaflet. You can read every leaflet on CIMA, the Spanish medicines agency's database. In the UK and the US the leaflet says "sensitivity to sunlight" or "photosensitivity".

How do you know it is a reaction to a medicine?

Think of it if you burn much more than usual after little sun, or if only uncovered skin reacts after you start a new medicine.

• Redness, burning or pain on the face, neck, chest, forearms or the backs of the hands.
• Blisters or swelling after only a short time in the sun.
• An itchy, bumpy or eczema-like rash the next day.
• Nails that lift off, or dark patches that take a long time to fade.

With ketoprofen gel the reaction appears where the gel went on, sometimes weeks later. The Spanish medicines agency (AEMPS) reviewed it in 2010 because of these reactions. It advises keeping the treated skin out of the sun while you use it and for two weeks after you stop.

What should you do if you react?

• Get out of the sun and cover your skin.
• Cool the area with cool, damp cloths and use a fragrance-free moisturiser.
• For pain you can take paracetamol. Follow the leaflet.
• Do not pop any blisters.
• If it was ketoprofen gel, stop using it, wash the skin and get advice.
• If it is a prescribed medicine, do not stop it on your own. Talk to your doctor or pharmacist. They may switch it, change when you take it or tell you how to protect your skin.

If it looks like a bad burn, read our guide to sun poisoning and when to worry.

How can you protect your skin while you take one?

• Stay in the shade in the middle of the day, when the Spanish sun is strongest.
• Wear clothes that cover you, a wide-brimmed hat and sunglasses.
• Use broad-spectrum sun cream with high UVA protection. Put more on after swimming or sweating.
• Remember that UVA light passes through clouds and car windows.
• Do not use sunbeds.

For hydrochlorothiazide, the AEMPS warned in 2018 that long-term use may raise the risk of non-melanoma skin cancer. If you take it, protect your skin and check it. See a doctor about any new or changing spot.

When to see a doctor and when to call 112

See a doctor soon if you have large blisters, a fever or feel unwell, if the rash is not better after a few days, or if it spreads to covered skin. Also ask if you are not sure whether to keep taking your medicine.

Call 112 if your face, lips or tongue swell, if you find it hard to breathe, or if you are confused or very dizzy after a long time in the sun.

Frequently asked questions about photosensitizing medications

Getting a medical assessment

If you are in Spain and think a medicine has caused a sun reaction, you can book a video consultation with Dr. Pedro Yelamo Vera, a physician registered in Spain. You can also read about sunburn and sun damage. A prescription is never guaranteed: it is issued only where clinically appropriate after a genuine evaluation, as a private electronic prescription under Spanish law. This service is for urgent, non-emergency care. In an emergency, call 112.

This guide is general information. It does not replace the package leaflet or the advice of your doctor or pharmacist.