A lice-killing lotion containing 1% permethrin or a mousse containing pyrethrins and piperonyl butoxide can be used to treat pubic (crab) lice. These products are available over-the-counter without a prescription at a local drug store or pharmacy. These medications are safe and effective when used exactly according to the instructions in the package or on the label. Lindane shampoo is a prescription medication that can kill lice and lice eggs.
Trichomoniasis is another type of vaginal infection. It is caused by a single-celled parasite that is usually spread through sex. In addition to causing bleeding after sex, it can also cause vaginal discharge and itching.
Because sperm can fertilize an egg for 72 hours (3 days) after ejaculation, having sex during a girl's period is risky. Having unprotected sex at any time is risky: Along with the chance of getting pregnant, you can also get a sexually transmitted disease (STD), such as chlamydia, genital warts, or HIV.