Oscier and Milner [1] point out that hypersensitivity reactions to paracetamol are rare. Whilst this might be the case it is worth commenting further on this issue. Hassani et al [2] studied hypersensitivity to cyclo-oxygenase inhibitory drugs in children. They found some cross-sensitivity between non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol.10.6% of NSAID-sensitive children reacted to paracetamol. Conversely, and in contrast, all paracetamol-sensitive children reacted to NSAIDs. The hypersensitivity reaction to paracetamol may include full blown anaphylaxis in both adults and children. Gowrinath et al [3] reported an anaphylactic reaction to paracetamol in a 58 year old woman, and Liao et al [4] reported a case in a 9 year old girl. The cross-sensitivity between paracetamol and other cyclo-oxygenase inhibitors would indicate a non allergic hypersensitivity, but allergic hypersensitivity may also occur [2]. de Paramo et al [5] suggested an IgE-mediated mechanism in four patients with adverse reactions to paracetamol and, interestingly, they tolerated aspirin and other non-steroidal anti-inflammatory drugs.

There are several learning points from this. Firstly, although hypersensitivity to paracetamol is unusual, it does occur in both children and adults and may be severe. Secondly, there may be cross-sensitivity with other cyclo-oxygenase inhibitors, depending on the underlying immunological mechanism. Thirdly, adverse events to drugs are proportional to their usage. As the use of intravenous paracetamol becomes more common place, we need to be prepared for the occasional reaction. Certainly, in the event of anaphylaxis occurring during anaesthesia, a possible reaction to paracetamol should be investigated along with other drugs used.

T.A. King

East Sussex Hospitals NHS Trust

East Sussex, UK

References

1.Oscier CD, Milner QJW. Peri-operative use of paracetamol. Anaesthesia 2009; 64: 65-72.

2.  Hassani A, Ponvert C, Karila C, Le Bourgeois M, De Blic J, Scheinmann P. Hypersensitivity to cyclooxygenase inhibitory drugs in children : a study of 164 cases. Eur J Dermatol 2008; 18: 561-5.

3. Gowrinath K, Balachandran C. Anaphylactic reaction due to paracetamol. J Indian Med Assoc 2004; 102: 223-6.

4. Liao CM, Chen WC, Lin CY. Study of an anaphylactiod reaction to acetaminophen. Acta Paediatr Taiwan 2002; 43: 147-52.

5. de Paramo BJ, Gancedo SQ, Cuevas M, Camo IP, Martin JA, Cosmes EL. Paracetamol (acetaminophen ) hypersensitivity. Ann Allergy Asthma Immunol 2000; 85: 508-11.