Competitive athletes suffering from a sore throat should think twice before popping a lozenge into their mouths.

Or at least examine the ingredients of the throat candy they are about to suck on.

Higenamine, which can dilate the windpipe, was added to the prohibited list for athletes by the World Anti-Doping Agency (WADA) and the new ruling came into effect this month. The chemical is contained in nandina, small red berries traditionally used as herbal medicine and used in several popular nonprescription throat lozenges.

It's now a hot topic among Internet users due to the popularity of nandina.

The Japan Table Tennis Association (JTTA) sent out official notification of the change in December to coaches and trainers nationwide to make sure players avoid anything with nandina in it.

The prompt notification was made as the national table tennis championship is scheduled to start Jan. 16 at the Tokyo Metropolitan Gymnasium in the capital's Shibuya Ward.

The JTTA also reminded its players about ephedrine, an active component taken from the ephedra plant. It has been banned for some time and is an ingredient in Asada-ame throat lozenges.

“We would like concerned persons (competitive athletes) to be thoroughly aware of what they take,” said a spokesperson from Tokiwa Pharmaceutical Co, which sells Nanten-nodo-ame throat lozenges that contain nandina.

A rumor making the rounds online asserts that the popular herbal Ryukakusan Throat Refreshing Candy includes higenamine, but it does not.

The candy's manufacturer, Ryukakusan Co., posted a statement on its website: “(Ryukakusan Throat Refreshing Candy products) contain no higenamine component at all. Please be assured.”