There's actually little research that they do, beyond placebo. It works a lot better in animal trials than with humans. Probably because of differenced in our a

There's actually little research that they do, beyond placebo. It works a lot better in animal trials than with humans. Probably because of differenced in our ability to actively cool ourselves. https://bjsm.bmj.com/content/46/4/296 https://bjsm.bmj.com/content/46/4/296