"Can I perform oral sex when my girl friend has her period?"

If you are not sure that your lover doesn’t have an STD, you have to use a dental dam to protect yourself. If - for whatever reason - you don’t use a dental dam, then you better avoid oral sex during her period. If you do lick her, prevent blood from entering your mouth in connection with HIV. If she doesn’t have a STD then there’s no problem having oral sex during her period. If you find it messy, ask her to wash her vulva and put a clean tampon in her vagina before you start.