UKPAN Statement on withdrawal of Pholcodine containing products

16th March 2023

In light of the recent withdrawal of pholcodine-containing products due to concerns about a possible link to neuromuscular blocking agent allergy, the UK Perioperative Allergy Network* has written the following response.

Allergic reactions to neuromuscular blocking agents (NMBAs) are extremely rare. Best estimates in the UK are that for every 10,000 patients given one of these medicines, one patient may suffer an allergic reaction to it (1). The reason why some people develop this problem is only partially understood and is the subject of ongoing research. The biggest risk factor appears to be previous exposure to an NMBA, but there may be other reasons why people become allergic to this group of drugs. 

One theory is that the use of pholcodine-containing cough syrups may predispose patients to NMBA allergy. However, because these events are so rare it is very difficult to be certain if this is true. Even if a link were confirmed, the increase in risk would be extremely small.

Since there are lots of good alternatives to pholcodine-containing products and there is only very limited evidence of pholcodine providing benefit in terms of cough suppression, the Medicines and Healthcare products Regulatory Agency (MHRA) have decided that, on balance, pholcodine-containing cough syrups should be removed from the market.

Around half of the general anaesthetics given in the UK involve the administration of an NMBA. Where one is indicated, anaesthetists are aware of the potential for adverse reactions, including allergic reactions. Anaesthetists are highly skilled at managing allergic reactions and undertake regular training for this throughout their careers.

Despite the recent MHRA guidance, our view is that there is no benefit to the patient or their anaesthetist to ask about previous use of pholcodine-containing cough medicines. The anaesthetist will only give an NMBA if this is clinically indicated, and the risk of an allergic reaction remains extremely small. If an NMBA is indicated, but not given, this would substantially increase other risks associated with anaesthesia and surgery and may make it impossible for the procedure to be completed. 

We therefore do not support the screening of patients for use of pholcodine-containing products in the previous 12 months and advise anaesthetists to use an NMBA where this is clinically indicated.

* The UK Perioperative Allergy Network is a multidisciplinary forum for anaesthetists, allergists and immunologists who work in this field. We are a UK-wide network created jointly by the British Society for Allergy and Clinical Immunology, Association of Anaesthetists and the British Society for Immunology Clinical Immunology Professional Network.

1. Harper N. et al. Anaesthesia, Surgery and Life-Threatening Allergic Reactions. BJA 2018
2. https://www.gov.uk/drug-safety-update/pholcodine-containing-cough-and-cold-medicines-withdrawal-from-uk-market-as-a-precautionary-measure (accessed 15/03/2023)

More information is available for patients in General anaesthetics and pholcodine in
cough medicines leaflet from Anaphylaxis UK www.anaphylaxis.org.uk/fact-sheet/general-anaesthetics-and-pholcodine-in-cough-medicines/