We all know - don't we? - that the over-the-counter cough medicines don't do much to help fight our children's coughs. So it's not an enormous leap of logic to conclude that they don't do much for us adults either.
Researchers couldn't find any convincing evidence that cough remedies are effective when they reviewed 25 studies. Six of the nine studies that were paid for by the manufacturer came back with a positive result, compared with just three of the 16 trials that were independently funded.
The new study, carried out by the Cochrane Collaboration, follows a warning given by America's drug regulator, the Food and Drug Administration, not to give the remedies to children younger than two years.
(Source: Cochrane Database of Systematic Reviews, 2007; 4: CD006088).