Researchers link common cough medicines like Night Nurse to fatal allergic reactions in patients undergoing surgery

A cough medicine taken by millions of Britons can cause a fatal allergic reaction in patients undergoing surgery.

Experts suspect that pholcodine, a cough suppressant found in popular products such as Day Nurse and some Covonia syrups, causes life-threatening anaphylactic shock when combined with certain narcotics. This causes the patient’s blood pressure to drop and the airways to narrow, blocking breathing.

Concerns about the safety of pholcodine are such that the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has launched an investigation and is advising patients to tell anesthetists if they have taken the drug in the year before the knife took. .

Last year, the European Medicines Agency (EMA) recommended a ban on the drug. It was also previously withdrawn from sale in France. This move followed a series of French and Australian studies showing that patients who took pholcodine within a year were more likely to have a specific reaction to two of the most common anesthetics, rocuronium and suxamethonium, which in approx. a quarter of the cases used are operations.

Patients are asked to tell their doctor if they have taken cough medicine such as Night Nurse in the year before surgery (photo by models)

Pholcodine is a non-sedating opiate – therefore it is not included in the Sleep Inducing Night Nurse.

It suppresses cough reflexes by reducing nerve signals sent from the brain to the muscles involved in coughing. Experts believe that due to the similar chemical composition of anesthetics, some people’s immune systems may overreact and go into anaphylactic shock.

The link to anaphylaxis was discovered in 2007 when Norwegian health authorities found that there were ten times more anesthesia-related deaths than in neighboring Sweden, where pholcodine was not available in over-the-counter medicine.

Health chiefs in Norway subsequently removed pholcodine from sale and the number of allergy deaths during surgery dropped from around five a year to zero.

In 2014, the results of a French study of more than 500 patients suffering from allergic reactions to anesthesia also concluded that those who had recently taken pholcodine were more likely to be affected.

At the time, EU health authorities considered this insufficient evidence to categorically prove the link and called for further studies. However, subsequent research from Australia and New Zealand raised concerns again. In 2021, doctors at Sir Charles Gairdner Hospital in Perth published the results of an eight-year study that analyzed risk factors for allergic reactions after surgery in 145 patients. They concluded that pholcodine use in the year before surgery was a significant risk factor.

The Australian New Zealand Anesthetic Allergy Group, a team of specialist doctors working to prevent allergic reactions during operations, claims the drug is responsible for at least seven deaths every three years.

However, some British experts say these concerns are unfounded.

Dr Penny Ward, Visiting Professor of Pharmaceutical Medicine at King’s College London, says: “Studies estimate this happens in eight out of 100,000 procedures. This means that even if pholcodine increases the risk, the likelihood of an allergic reaction is still very low.”

In addition, Dr. Ward that the EMA-recommended ban is based on the idea that the cough medicines have minimal benefits. “The decision was based on the fact that pholcodine is used to treat a dry cough that usually goes away without treatment,” she says. “The evidence that it relieves symptoms is very weak.

“I suspect that many of the experts who made the decision thought that when a patient gets the same benefit from drinking warm water with honey and lemon, it is not worth the risk, even though the risk small.” could.

“Several major safety reviews have been carried out over the years and yet health chiefs in Australia, the US and the UK have not yet recommended a ban – probably because this type of allergic reaction is so rare.”

British health authorities have yet to confirm the link. The Royal College of Anesthetists says a link between pholcodine and allergic reactions to anesthetics is “possible” and notes in a recent report that more research is needed. So far, no study has provided conclusive evidence of the problem.

There are also questions about the reliability of studies that rely on patients recalling cough medicines they took in the year before their surgery.

Pharmacist Claire Frank, of the UK Clinical Pharmacy Association, says: “A year is a long time to think back and remember – especially when there are so many different OTC cough medicines out there.

“Patients may not know if the cough medicine they have taken contains pholcodine or not.”

In a statement last night, the MHRA said: “There is already a known link between pholcodine and a very low risk of a serious allergic reaction to muscle relaxants used during general anaesthesia. We will release further details in due course.”