Cough medicine often contains cough suppressants and expectorants.
A cough medicine is a medicinal drug used to treat coughing and related conditions. Dry coughs are treated with cough suppressants (antitussives) that suppress the body's urge to cough, while productive coughs (coughs that produce phlegm) are treated with expectorants that loosen mucus from the respiratory tract. These medicines are widely available in the form of cough syrup, also known as linctus.
Diphenhydramine and its derivatives are often useful as non-narcotic cough suppressants by themselves and they dry out bronchial secretions, boost the effects of opioids and combat cold/allergy symptoms caused by immune responses which release histamine into the system.
In 2002, researchers at the University of Bristol (Schroeder & Fahey) published a study in the British Medical Journal indicating that some cough medicines are no more effective than placebos for acute coughs in adults, including coughs related to upper respiratory tract infections.[1] In 2006, the American College of Chest Physicians published a guideline that had the dual message that many over-the-counter cough medicines are not effective and that those that are effective in treating the symptom do not treat the underlying cause; the underlying disorder emphasized by the guideline was pertussis (whooping cough) in the elderly.[2]
Recent studies have found that theobromine, a compound found in cacao, is more effective as a cough suppressant than prescription codeine. This compound suppresses the "itch" signal from the nerve in the back of the throat that causes the cough reflex. It is possible to get an effective dose (1 g, though 0.5 g may be sufficient, according to PMID 15548587) from 50g of dark chocolate, which contains 2 to 10 times more cacao than milk chocolate. Cocoa powder contains roughly 0.1 g per tablespoon (5g).[3] Theobromine was also free from side effects in the blind tests.[4]
Mass poisonings due to diethylene glycol
According to the New York Times, at least eight mass poisonings have occurred as a result of counterfeit cough syrup, mostly if not totally produced in China, substituting inexpensive diethylene glycol in place of glycerin. Recently, 365 deaths were reported in Panama, which were associated with cough syrup laced with diethylene glycol. [5]
