An ingredient in chocolate may actually be a more effective cough medicine than traditional remedies, a new study suggests.

And not only that, the UK-based research showed that the cocoa-derived compound had none of the side effects associated with standard drug treatments for persistent coughs.

“These sorts of coughs, often lasting for weeks after a viral infection, can be difficult to treat, especially since it is not possible to give large doses of opiate-based medication to patients due to the side effects,” says Peter Barnes, professor of thoracic medicine at Imperial College London, UK, who led the study.

Barnes and colleagues gave 10 healthy volunteers tablets containing: theobromine, a constituent of cocoa or; codeine, the cough suppressant against which other drugs are measured or; a placebo.


The volunteers were then asked to inhale a gas containing capsaicin – a derivative of chilli peppers – which induces coughing and is used as an indicator to test the effectiveness of cough medicines.

Lung patients

Those given theobromine needed about one-third more capsaicin to produce coughing than those who took codeine. Codeine was only marginally more effective than the placebo at preventing coughing.

Dame Helena Shovelton, chief executive of the British Lung Foundation, says: “The results of this research sound very promising. Persistent coughing often affects lung disease patients so this could be a progressive step in treating it.”

But she advises that “patients to speak to their family doctor before changing their medication or treating their cough with chocolate”, as tempting as that may be.

Drowsiness and constipation

Notably, theobromine appeared to have no unwanted side effects. This is not true of codeine, which is a narcotic and lists drowsiness and constipation among its negative effects.

“We gave them the equivalent of about two cups of cocoa,” Barnes explains: “The next stage will be to look at different doses.”

The researchers believe theobromine acts on the sensory nerve endings of the vagus nerve, which runs through the airways in the lungs to the brain. Capsaicin stimulates these endings to provoke coughing.

The team explored their hypothesis by looking at theobromine’s action on the vagus nerve in separate experiments involving guinea pigs and excised human trachea tissue.

Their results confirmed that theobromine does indeed inhibit the capsaicin-induced sensory nerve depolarisation in the vagus nerve.

Journal reference: Federation of American Societies for Experimental Biology Journal (DOI: 10.1096/fj.04-1990fje)

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