Thank you for your question. No its not harmful to lick the vulva or vagina provided both of you are clear of any sexually transmitted infections or do not have sex with anyone else. If you have multiple partners or either of you has had unprotected sex with anyone else, you need to use a barrier between your tongue and her vulva so there is no direct contact between your body fluids. It is better to keep yourself safe rather than depending on the word of another person. Make it a habit never to have sex without a condom or a barrier of latex or vinyl even for oral sex. hope this helps