Acute or subacute adverse cutaneous reactions to a drug or medicine

Ranges from a mild/unnoticed rash to severe cutaneous adverse reaction (SCAR)

Types

Urticarial eruption

• An urticarial eruption is characterized by itchy red wheals (hives) with angio-oedema.
• A wheal can last a few minutes and can change form.
• Urticaria is type 1 IgE-mediated hypersensitivity reaction and so occurs very rapidly after taking the drug.
• It can be diagnosed by a skin prick test and is treated with an antihistamine.

Common causes of an urticarial eruption include:

• NSAIDs
• Beta-lactam antibiotics
• Opiates
• ACE-inhibitors

Morbilliform eruption

• fine erythematous macules and papules are distributed over the trunk
• It is a type IV T cell mediated hypersensitivity reaction and so there is a delay of 1-2 weeks between starting the drug and the rash.
• However on re-exposure the rash can appear much faster.

Common causes include: