Oh yay! I’m so glad that you asked this question, since we don’t talk about it nearly enough.
This goes for all types of sex between all types of people/genders/sexes: If you are unsure of your partner’s sexually transmitted infection status, follow this very basic rule: don’t mix fluids.
If you know someone well enough that you both get tested and decide that you’re willing to commit, you can decide to become fluid-bonded to them. This means that you decide to share bodily fluids with one another and begin to participate in sex acts without a barrier method.
Until then, use barrier methods.
For people with vaginas having sex with people with vaginas (try to say that 10 times fast), here are some good basic rules:
- Use dental dams for oral sex. If you don’t have a dental dam you can cut an external or internal condom down one side and open it up to lay against the vulva or anus. You can even use saran wrap.
- Use latex or non-latex disposable gloves when inserting fingers/hands/fists into vaginas/rectums. Once the glove has been used in one vagina, do not use it for the other vagina. You’re not just protecting your fingers from the vaginal discharge, you’re protecting each vagina from the other. Keep the box on hand and use them liberally. They’re cheap compared to an STI, I promise. Additionally, once the glove has been used in an anus, it should never go back into any vagina.
- Wash your hands and fingernails well before sex, even if gloves are going to be used.
- Clean sex toys before use, and cover them in condoms during sex. Each partner should get their own condom. Again, I promise that condoms are cheaper than STIs.
- Use lots of lube. On the one hand, this is just for fun. On the other hand, lube protects vaginal tissue, making it less likely to get a scrape or cut that leaves people open to infection.
- Use internal (female) condoms as desired. You can combine them with dental dams and gloves while giving oral sex that includes fingering/dildos/vibrators.
Read more here:
Safer sex for lesbians
Safer Sex for Lesbians and Bisexual Women