What are phototoxic reactions?

A phototoxic reaction is where the damage to the skin is caused by the chemicals. These chemicals may be activated or made more damaging by exposure to sunlight. This is quite common, and an exaggerated sunburn or rash will develop only a few minutes after being exposed to sunlight. The skin can become reddened and swollen, and may or may not be itchy. You may also develop blisters on the skin. This reaction only happens in places exposed to sunlight, which are commonly the cheeks and bridge of the nose, and hands and arms. Less commonly, skin might have changed colour – a blue-greenish colour is associated with amiodarone. In some cases, the nail might lift off from the nail bed (photo-onycholysis).

Drugs that cause phototoxic reactions include:

  • Phenothiazines, such as chlorpromazine (which can be used in the treatment of psychoses such as schizophrenia or bipolar disorder) and promethazine (which is an antihistamine with sedative effects).
  • Amiodarone, which is a drug used in the treatment of an irregular heart rhythm.
  • Thiazide, which is another drug used to treat high blood pressure.
  • Tetracyclines, sulphonamides, quinolones (which drugs used in infections), and griseofulvin (an anti-fungal drug).
  • NSAIDs, which are a type of painkiller, such as ibuprofen
  • Sulphonylureas, such as tolbutamide, which are used in the management of type 2 diabetes mellitus.

Photosensitivity Guide Index:

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