What's an over-the-counter treatment for gardnerella?

Gardnerella: No, there is no effective otc treatment for gardnerella. Also, your sexual partner needs to be treated. Otherwise, you will get a ping pong reinfection.

No good otc: Gardnerella or bacterial vaginosis is a common vaginal infection cause by over growth of a bad bacteria or death of good bacterial. It can be affected by spermicide, doucheiing (don't do this!), overenthusiastic cleaning or bad luck. It is easilly treated with oral medication or vaginal suppositories prescribed by a doctor but i would not recommend treating it yourself.