Does a sauna help if you have a cold?

KLAFS FAQ for well-being 

Using a sauna regularly strengthens your immune system and your circulation. This in turn has a positive effect on your metabolism – and helps to prevent you catching flu. If you feel like you might be about to come down with something, taking one or two sauna rounds can prevent it from exploding in full force. There’s no reason in such cases to avoid using the sauna. But if your immune system is already on maximum alert, or you’ve already got a temperature, the heat will do more harm than it does good.