Cough medicines that include Pholcodine can cause anaphylaxis

I was reminded last week by an excellent post on Ruth Holroyd’s What Allergy? blog of the Pholcodine issue which, 25 years after it was first discussed, has still not been resolved in the UK.

Pholcodine is a drug that is to be found in a wide range of cough medicines. Unfortunately pholcodine has a similar molecular structure to the muscle relaxing drugs which are routinely given to patients about to undergo operations. If that patient has recently (within the last year) had an allergic reaction to pholcodine they could easily react to a muscle relaxant administered prior to an operation.

According to research and an article in FoodsMatter by the great, but sadly late, Dr Harry Morrow Brown, a French study, published in Anesthesiology as long ago as 2003, ‘found that in 1999, in France alone, there were 518 cases of anaphylactic shock during surgery, of which 300 were attributable to these drugs’.

In the early 2000s further investigations were carried out by Professor Johansson from Stockholm, in collaboration with Professor Florvaag from Bergen. They observed that while the risk of pre-operative anaphylaxis under anaesthetic was negligible in Sweden where pholcodine cough syrups were not available, in Norway where they were, dangerous reactions to pre-operative muscle relaxants were common. As a result of their work in March 2007 cough medicines containing pholcodine were banned in Norway and two years later, reported reactions and deaths due to muscle relaxants had dropped to zero.

In 2010 Dr Morrow Brown was calling for all pholcodine-containing cough medicines to be banned in the UK. Sadly, and despite further studies in 2014 and 2021 relating pholcodine to anaphylactic incidents (and quoted by Ruth in her post) this has not happened. As Dr Harry rightly said then – and Ruth confirmed in her blog post – most cough medicines achieve meagre results and can be addictive. So why are they still being sold?

So, if you have a cough, instead of buying a bottle of cough medicine, check in to Ruth’s post where she offers a number of suggestions for more natural – and effective – ways of dealing with it.

30th March 2023

I am happy to report that at more or less the same moment as I was publishing this piece the Medicines and Healthcare products Regulatory Agency were taking action and have now withdrawn  Pholcodine-containing cough medicines from the market – see this guideance.