Symptoms
Photosensitivity often manifests like sunburn in extensive skin redness, pain, a burning sensation, blistering, and hyperpigmentation after healing. Other possible skin reactions include eczema, itching, urticaria, telangiectasia, tingling, and edema. The nails may also be affected less frequently and may peel off in front (photoonycholysis). The symptoms are limited to the areas of the body that have been exposed to solar radiation. Photosensitivity is a risk factor for the development of white and black skin cancer. This has been shown, for example, for the antifungal drug voriconazole.
Causes
The cause of drug-induced photosensitivity is topical or systemic administration of a photosensitizing drug. When combined with UVA/B radiation or visible light, an adverse skin reaction occurs. UVA is the most common trigger. Two mechanisms of occurrence are distinguished. Phototoxicity is a non-immunological reaction in which the active ingredient absorbs and subsequently releases energy, causing damage to cellular components and the generation of reactive oxygen species (ROS). It usually manifests itself like a sunburn. The rarer photoallergy is based on a delayed allergic reaction of type IV. The active substance forms an allergen together with a protein. Unlike phototoxicity, photoallergy does not occur in every person and only after sensitization. Photoallergy usually causes itchy contact dermatitis. The following table shows a small selection of photosensitizing agents:
| Antiarrhythmics | Amiodarone, quinidine |
| Antibiotics | Quinolones: ciprofloxacin, sulfonamides, tetracyclines |
| Antifungals | Griseofulvin, itraconazole, ketoconazole, voriconazole |
| Calcium channel blockers | Amlodipine, diltiazem, nifedipine |
| Diuretics | Furosemide, thiazides: hydrochlorothiazide |
| Kinase inhibitors | Vemurafenib |
| Neuroleptics | Phenothiazines: chlorpromazine |
| NSAIDS | Celecoxib, dexibuprofen, diclofenac, ketoprofen, mefenamic acid, naproxen, piroxicam |
| Botanicals | Furanocoumarins |
| Retinoids | Acitretin, isotretinoin |
| Statins | Fluvastatin, rosuvastatin |
Diagnosis
The diagnosis can be made on the basis of the clinical picture, physical examination, patient history, provocation tests, and laboratory methods. Other skin diseases, common sunburn, and other photodermatoses must be excluded.
Prevention
It is important for patients to be informed by health care professionals of the risks and precautions of drug use or to read the package insert carefully.
- Avoid sun exposure, especially between 11 am to 3 pm.
- Wear protective clothing and sunglasses.
- Sunscreen with a high protection factor.
- In any case, a visit to the solarium is not recommended.
Treatment
For treatment, discontinuation of the triggering drug may be considered. Especially with short-acting agents, it is helpful to administer the drug in the evening. Cooling with water is a first measure for sunburn, for example with moist compresses or with a shower. Treatment of skin reactions may include hydrating skin care products and, in the case of allergic reactions, topical glucocorticoids.