Photosensitization refers to the lowering of the light stimulus threshold of the skin. This can be done by substances acting on the skin from the outside or from the inside.Among these substances, there are a variety of drugs.
One can distinguish photoallergic and phototoxic reactions.
Symptoms – complaints
Exposure to the substances may cause various symptoms:
- Increased sunburn
- Erythema
- Change in pigmentation
- Pseudoporphyria – change in the skin with increased vulnerability of the skin and blistering.
- Photoonycholysis – detachment of the nail plate.
- Lichenoid reactions
- Subcorneal pustule formation
- Subacute cutaneous lupus erythematosus
- Phototoxic purpura
- Photocarcinogenesis – development of malignant neoplasms such as squamous cell carcinoma.
Photosensitizing drugs include:
- Antidepressants (amitriptyline, clomiramine, desipramine, doxepin, imipramine, nortriptyline, trimipramine).
- Antiepileptic drugs (carbamazepine, lamotrigine, phenobarbital, phenytoin, topiramate, valproic acid).
- Antihistamines (cyproheptadine, diphehydramine, loratadine).
- Antimicrobials (ciprofloxacin,doxycycline, enoxacin, gentamycin, griseofulvin, isoniazid, lomefloxacin, minocycline, nitrofurantoin, norfloxacin, ofloxacin, oxytetracycline, sulfamethoxazole/trimethoprim, sulfasalazine).
- Antipsychotics (chlorpromazine, chlorprothixene, fluphenazine, haloperidol, perazine, promethazine, promazine, thioridazine).
- Diuretics (amiloride, bendroflumethiazide, etycrynic acid, furosemide, hydrochlorothiazide, spironolactone, triamterene, xipamide).
- Gold salts
- Hematoporphyrin
- Hormones (corticosteroids, estrogens, progesterones, spironolactone).
- Cardiovascular agents (amiodarone, captopril, quinidine, disopyramide, enalapril, fosinopril, hydralazine, nifedipine, ramipril, simvastatin).
- Non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen, indometacin, ketoprofen, mefenamic acid, naproxen, phenylbutazone, tiaprofenic acid).
- Proton pump inhibitors (esomeprazole, lansoprazole, omeprazole, pantoprazole, rabeprazole).
- Substances against malaria (quinine, chloroquine, hydroxychloroquine, mefloquine, pyrimethamine).
- Systemic dermatics (isotretinoin, methoxsalen).
- Cytotoxic agents (azathioprine, dacarbazine, fluorouracil, methotrexate, procarbazine, vinblastine).
Diagnostics
Diagnostic procedure for suspected phototoxic/photoallergic reaction:
- Light staircase examination with determination of minimal erythema doses – Caveat: Do not discontinue medication beforehand.
Prophylactic measures
- Take medications with a short half-life in the evening
- Avoid solariums
- Avoid sunlight between 11 am and 3 pm
- Apply sunscreen with high UV-A protection
- Wear textile light protection
- For long-term use: apply UV-impermeable films to windows
Therapeutic measures
- Topical glucocorticoids, in combination with antiseptics if necessary.
- Burn therapy for extensive blistering reactions.
- Hydroquinone (5%), hydrocortisone (1%) and tretinoin (0.1%) should be used for hyperpigmentation
- In exceptional cases, laser treatment is indicated (for amiodarone or minocycline pigmentation).
