A team at British-based drugs company called SEEK has isolated a naturally occurring substance in cocoa which it says stops the “root cause” of the irritating condition, ‘The Daily Telegraph’ reported.

At present, most medications to control the symptoms are opiate-based ones like cough syrups containing codeine, a narcotic.

Now, the scientists are helping develop a medication based on a drug called theobromine, which they say “has been shown to inhibit the inappropriate firing of the vagus nerve, which is a key feature of persistent cough”.

The substance is found in “significant quantities in cocoa-based products”, say the scientists.

Prof Alyn Morice from the Hull Cough Clinic, said: “Due to the drawbacks of current opioid drugs such as codeine, we are in desperate need of a non-opioid treatment with a drastically improved side effect profile for patients.”

He said that while it was “theoretically possible” to get enough theobromine in a bar of dark chocolate to alleviate a cough, studies had yet to be done to reveal the exact dose required.