Paracetamol hypersensitivity

Type B effects are not related to the pharmacological properties of these drugs. Serious side effects may occur. Allergic skin and liver reactions to aspirin and paracetamol have been reported with risk of fibrosis, particularly in the retroperitoneal region for methysergide and hypersensitivity reactions with NSAID and pure analgesics. 

Side-effects are rare and may include hematological reactions, leucopenia, agranulocytosis and other hypersensitivity reactions. Paracetamol has a narrow therapeutic dose range and overdosage induces severe liver and renal damage (Lewis and Paloucek, 1991) via accumulation of a toxic metabolite, N- acetyl-benzoquinoneimine (NABQI). Acetylcysteine or methionine, which increase glutathione conjugation of the metabolite, are used as the antidote. 

On rare occasions therapeutic doses of paracetamol have been reported to cause hepatotoxicity as a result of hypersensitivity. Rechallenge with small doses triggered a recurrence of the reaction [9]. 

Hypersensitivity pneumonitis has been associated with co-proxamol (paracetamol plus dextropropoxyphene) (5). 

Acute hypersensitivity reactions due to paracetamol are rare (SEDA-22,114), but can be life-threatening (67). 

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