TheMarker found that Listerine costs 30% more than Colgate and Orbitol mouthwashes, almost 60% more than Aquafresh, and double the cost of the private-label brand of supermarket chain Super-Sol.

Last July, Listerine was selling for NIS 30 in a special deal to capture market share, but even then it cost far, far more than it does abroad.

The drugstore chain New-Pharm, which imports Listerine, explained that the the antiseptic mouthwash product sold in Israel is kosher.

The product's manufacture is supervised by the Chief Rabbinate and the mouthwash undergoes the processes needed to sell it to the ultra-Orthodox community, New-Pharm said. Supervision at that level involves extra costs. Kosher Listerine is also sold in the U.S. at about the same price as in Israel, New-Pharm said.

Also, it added, shelf prices are set by stores: the company and distributor aren't involved.

Listerine is also popular in the United States, where its marketing slogan is that its antiseptic quality kills the bacteria causing bad breath. It is manufactured by Johnson & Johnson.