The hidden menace that can cause death during surgery. How a cough syrup can kill you.

Dr Harry Morrow Brown reports

Nowadays muscle relaxing drugs are given routinely before anaesthesia for surgical operations, but these drugs are also the commonest cause of potentially fatal anaphylactic shock during surgery. A French study, published in Anesthesiology in 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.

The real cause of these reactions was a mystery until a recent meeting of the Allergy Research Foundation at the Royal Society of Medicine in London when Professor Johansson, from Stockholm, presented important new research (reported in Allergy) in collaboration with Professor Florvaag from Bergen, proving conclusively that anaphylactic shock from muscle relaxant drugs is most often caused by taking cough syrups containing the cough suppressant drug pholcodine, which can be purchased freely from any pharmacy in Britain, France, and Australia.

Professors Florvaag and Johansson’s research began some years ago when they questioned why dangerous reactions to these drugs were common in Norway, yet none were reported in Sweden. They also observed that pholcodine cough syrups were very popular in Norway, but not available in Sweden. Testing stored blood from patients who had had reactions during surgery showed that many had very high levels of IgE allergy antibodies to pholcodine. Further research revealed that part of the pholcodine molecule has a similar structure to the molecules of these muscle relaxing drugs. When patients who had had reactions were traced years later and given pholcodine cough syrup again antibodies reappeared very quickly in dangerous amounts. This research caused these cough syrups to be forbidden in March 2007 in Norway, with the result that in the last two years reactions have decreased remarkably and, in 2009, no reactions or deaths due to muscle relaxants have been reported in that country.

Eighty cough remedies, most containing pholcodine, are freely available in Britain. A troublesome cough is never fatal, and none of these remedies are really effective anyway. Help for severe coughs should be obtained from your doctor rather than get a potentially deadly cough suppressant from the pharmacy.

This new evidence is more than adequate to justify the withdrawal of cough mixtures containing pholcodine in the UK and other countries to prevent totally unnecessary anaphylaxis and death from anaphylactic shock due to muscle relaxant drugs.

Without testing for IgE antibodies to pholcodine before surgery neither patients nor anaesthetists can be aware if these deadly antibodies are present or not. As the risk of anaphylaxis is one in a thousand or more it may not be considered financially justifiable to test before every operation, but when IgE antibody is found to be present the risk of a reaction can be as high as one in twenty...

It is obvious that pressure should be applied to the relevant authorities for pholcodine to be withdrawn immediately from all medication.

H Morrow Brown  MD FRCP(Edin)  FAAAAI (USA)

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Public awareness of the potentially lethal effects of cough syrups must become more widely known to prevent unnecessary deaths and life-threatening attacks when patients are at their most vulnerable. What happens is that the patient goes through the usual procedures for an anaesthetic, which usually includes injection of a muscle relaxant into a vein, and becomes unconscious. Within minutes the patient suddenly stops breathing, with a very weak pulse and a precipitous drop in blood pressure. This crisis situation has to be recognised at once and emergency treatment, especially adrenaline, given immediately. Delay will be fatal.

It is disturbing to realise that nobody knows if they are carrying these lethal antibodies. This research by world renowned scientists has produced very strong evidence to support a ban on pholcodine in all the countries where is freely available.

First published in 2010

If you found this article interesting, you will find many more articles on anaphylaxis here, and reports of research into anaphylaxis here.
You can also find articles on peanut and tree-nut allergy here, cow's milk allergies here, egg allergy here, histamine intolerance hereand articles on a wide range of other allergic and intolerance reactions to a wide range of other foods here.

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