That tingling feeling on your lip is unmistakable. You know what's coming before you can see it. And if you've had cold sores before, you've probably noticed they show up at the worst possible times: when you're already run down, before something important, after a stretch of poor sleep.

Urinary tract infections (UTIs) are one of the most common infections I see in practice. If you have a vagina, chances are you've experienced one at some point — or you will. In fact, about 50–60% of women will develop a UTI at least once in their lifetime, and many will experience recurrent infections.