Drug-Induced Photosensitivity

How drug-induced photosensitivity happens

Some medicines absorb ultraviolet (UV) light, mostly UVA, which passes through window glass and clouds. The energized molecules either damage skin cells directly or trigger an immune reaction.

Typical areas are the face, the V of the neck, the backs of the hands and forearms. The areas under the chin and behind the ears are often spared.

Medicines that cause photosensitivity

This list is not complete. Check the leaflet or ask a pharmacist about any medicine.

Antibiotics and antifungals

• tetracyclines, especially doxycycline and demeclocycline
• fluoroquinolones (ciprofloxacin, levofloxacin)
• sulfonamides (trimethoprim-sulfamethoxazole)
• voriconazole, which also raises skin cancer risk with long-term use
• griseofulvin

Heart and blood pressure medicines

• hydrochlorothiazide and other thiazide diuretics, furosemide
• amiodarone, which can also cause blue-gray skin discoloration
• some calcium channel blockers and quinidine

Pain and inflammation

• NSAIDs, especially piroxicam, naproxen and ketoprofen gel

Skin and acne medicines

• isotretinoin and acitretin
• topical retinoids (tretinoin), which thin the outer skin
• coal tar products

Others

• chlorpromazine and some other antipsychotics
• tricyclic antidepressants
• St. John's wort
• some diabetes medicines (sulfonylureas)
• methotrexate and some cancer drugs (vemurafenib, 5-fluorouracil)
• hydroxychloroquine (rarely)
• psoralens, used deliberately in light therapy

Some plants (limes, celery, parsnip, figs) cause a similar reaction called phytophotodermatitis when juice on the skin meets sunlight.

Other features

• Photo-onycholysis: separation of the nails from the nail bed, especially with doxycycline.
• Pseudoporphyria: fragile skin and blisters on the backs of the hands, like porphyria, with naproxen and some others.
• Lasting dark marks after phototoxic reactions.
• Increased skin cancer risk with long-term voriconazole and hydrochlorothiazide.

Diagnosis

The diagnosis is usually based on the rash pattern, timing and medicine history. A dermatologist may perform:

• phototesting: exposing small skin areas to measured doses of UVA, UVB and visible light
• photopatch testing: for suspected photoallergy to creams or sunscreens
• blood tests to exclude lupus and porphyria, which also cause sun sensitivity

Other conditions to consider include polymorphous light eruption, ordinary sunburn and contact dermatitis.

Treatment

• Get out of the sun and avoid further exposure until the skin heals.
• Cool compresses and cool baths.
• Moisturizers and aloe vera gel.
• Pain relief: acetaminophen (paracetamol) or ibuprofen at the label dose, unless an NSAID is the suspected cause.
• Steroid creams or tablets for severe photoallergic or phototoxic reactions, prescribed by a doctor.
• Do not pop blisters.
• Review the medicine with your prescriber. Do not stop an important medicine on your own. Sometimes an alternative is available, or the dose can be taken in the evening, which may reduce phototoxic reactions for some drugs.

Prevention

• Use a broad-spectrum sunscreen of SPF 30 or higher with good UVA protection, applied generously 15 minutes before going out and reapplied every 2 hours.
• Wear long sleeves, a wide-brimmed hat and UV-protective sunglasses.
• Seek shade, especially between 10 a.m. and 4 p.m.
• Remember UVA passes through car and home windows. Car window film helps.
• Avoid tanning beds.
• Ask a pharmacist whether any new medicine causes sun sensitivity, especially before a vacation.

Frequently asked questions

Which medications cause sun sensitivity?

Common examples include doxycycline and other tetracyclines, fluoroquinolone and sulfa antibiotics, hydrochlorothiazide and other diuretics, NSAIDs like naproxen and piroxicam, amiodarone, voriconazole, isotretinoin and topical retinoids, some antipsychotics and St. John's wort.

What does a drug-induced photosensitivity rash look like?

A phototoxic reaction looks like a bad sunburn limited to sun-exposed skin, with redness, burning and sometimes blisters, often followed by darkening. A photoallergic reaction is an itchy, bumpy, eczema-like rash appearing 1 to 3 days after exposure.

How long does photosensitivity last after stopping a medicine?

It depends on how long the drug stays in the body. For most medicines, sensitivity fades within days to a couple of weeks after stopping. With amiodarone, it can last months. Photoallergic reactions occasionally persist for longer.

Can sunscreen prevent drug-induced photosensitivity?

Sunscreen helps but may not be enough, because many reactions are triggered by UVA, which is less blocked by some sunscreens. Choose broad-spectrum products with strong UVA protection, and combine with clothing, hats and shade.

Is doxycycline sun sensitivity dangerous?

It usually causes a painful, exaggerated sunburn and occasionally nail separation, which heal once you avoid the sun. It can be severe with intense exposure. Use strict sun protection while taking doxycycline and for a few days afterward.