Onset: Usually immediate (0-6 hours)
Duration: Resolution within 24-72 hours
Region(s) affected: Lips, eyelids, earlobes, tongue, mouth, larynx, genitalia
Morphology: Skin-coloured circumscribed edema involving the subcutaneous tissues. (can be asymmetrical/unilateral)
More details: Non-pruritic; often very frightening for patients; can be painful
Onset: 1-8 weeks after exposure
Duration: Weeks-months (even after discontinuing the suspected medication)
Region(s) affected: Classic distribution: Face, upper trunk, extremities (but can progress anywhere on the surface of the skin and can sometimes have mucosal involvement)
Morphology: Most commonly begins as an erythematous, pruritic, morbilliform rash
More details: Pruritis and fever usually precede cutaneous eruptions. Can cause facial edema, which can be mistaken for angioedema
Systemic systems involved:
Onset: Within 3-5 days (May include prodromal symptoms of an upper respiratory infection)
Duration: Approximately 2 weeks
Region(s) affected: Often appear on the extremities (hands, palms, extensor of the forearms, soles of the feet, etc.) and can spread inwards towards the trunk. May involve mucous membranes of the mouth and genitalia
Morphology: Well-demarcated, circular, erythematous papules; often “target” or “iris”-like
More details:
Onset: Delayed (often more than 72 hours), within the first 2-4 weeks following the initial dose
Duration: Usually fades within 2 weeks
Region(s) affected: Commonly begin on head, neck or upper torso, and progress downward to the extremities
Morphology: Often bilateral and symmetrical. Usually flat, barely raised, erythematous patches (one to several mm in diameter). Can also include papules
More details:
Onset: 5-20 hours after drug + UV light exposure
Region(s) affected: Areas most often exposed to the sun (ex: face, back of the hands, back and sides of the neck, extensor surfaces of the forearm, etc.). Classical presentation spares shaded areas, such as under the chin, under the nose, behind the ears.
Morphology: Often resembles exaggerated sunburn, sometimes with blisters. Sharp demarcation at sites where clothing or jewelry were present during light exposure
More details: Not common with beta-lactam antibiotics
Region(s) affected: Localized or generalized itching; more often generalized when drug induced
Morphology: Does not require visible cutaneous signs of a reaction
More details: Mechanism not always clear
Onset: Delayed (within 8 weeks of first exposure), but with abrupt onset of symptoms
Duration: Up to 6 weeks
Region(s) affected: Less than 10% of the body surface is affected. Can affect the skin, eyes, and mucous membranes; such as the lips, mouth, and genital mucous membranes
Morphology: Often begins with dusky red, flat lesions (sometimes target-like, similar to erythema multiforme), progressing to bullae and necrotic lesions. Leads to blisters and dislodgement of the epidermis
More details:
Onset: Delayed (within 8 weeks of first exposure), but with abrupt onset of symptoms
Duration: Up to 6 weeks
Region(s) affected: Greater than 30% of the body surface is affected. Can affect the skin, eyes, and mucous membranes; such as the lips, mouth, and genital mucous membranes. Hairy regions of the skin are often spared
Morphology: See Stevens-Johnson Syndrome; eventually can resemble extensive second degree burns
More details:
Onset: Immediate, usually within 36 hours
Duration: Rarely persist for more than 24 hours
Region(s) affected: Can occur in any location. Involves the superficial portion of the dermis, and not subcutaneous tissues
Morphology: Raised, erythematous areas of edema (wheals), sometimes with central pallor. Will often blanch with pressure
More details: