How many nights in a row is it safe to use BenGay? I want to know if I need to take a break or if I can use it every night if need be.

Ingredient Toxicity. The active ingredient of ben gay is methyl salicylate. Extended over use, especially in children, can be dangerous and even fatal. Older people such as adults have a larger body mass and are less likely to be affected, but there is always that possibility. Follow the directions for applications carefully.