Patients who have an allergic reaction to one cephalosporin drug may be inaccurately labelled as ‘allergic’ to the whole family of medicines, according to an article in the latest issue of Australian Prescriber. Drs Carlo Yuson and William Smith (Royal Adelaide Hospital) and Professor Constance Katelaris (Campbelltown Hospital) question the label ‘cephalosporin allergy’.

The structural diversity of medicines in the cephalosporin family make it unlikely that cross-reactivity occurs across the whole class. A person who may react to one cephalosporin may be able to tolerate other cephalosporins.

The authors also point out that a history of a penicillin allergy should not rule out the use of cephalosporins and vice versa. Recent studies have demonstrated cross-reactivity rates are as low as one per cent.

Clinicians need to be aware that cross-reactivity within the cephalosporin class and between cephalosporins and penicillins is statistically unlikely. This will help prevent unnecessary prescribing of other broad-spectrum antibiotics,” says Professor Katelaris.

Allergic reactions to cephalosporins can be life-threatening. Referral for further investigations is needed if a patient has a severe reaction.

Professor Katelaris says that taking an accurate history is essential when recording a reaction: “Clinicians should include the illness the antibiotic was used to treat, comorbidities, and concurrent drugs. A detailed description of the reaction is essential, including the date and the actual name of the drug rather than the family or class of drug.

The term ‘cephalosporin allergy’ should not be used. Professor Katelaris says “It is inaccurate and indicates a contraindication to the entire class of cephalosporins. Concepts of drug allergy have changed and we now know that such a blanket contraindication is usually inappropriate.”


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