Hi!

Thanks for asking your question! The short version is that any practices involving the exchange of fluids (blood, vaginal and anal secretions, semen, saliva) and contact with certain parts of the body (genital, anal, oral) can carry some degree of risk, regardless of your and your partners actual genital organs. More people being involved in the relationship could potentially increase risks of STIs, but there are definitely ways to be safe. Let me get into specifics. 

First here is a list of the more common sex acts (specifically between women), their risks (when not using any protection) and some quick tips :

Kissing (with exchange of saliva)

• • Common transmission : Herpes type 1 when there is an outbreak (cold sore)
  • Uncommon transmission : Herpes type 2, Syphilis, HPV (warts)
  • Impossible transmission : Chlamydia, Gonorrhea, Hepatitis B, Hepatitis C, HIV

• The presence of blood in the saliva of a partner infected with HIV (whose viral load is not controlled by medication), hepatitis B or C presents a low risk of transmission if there are microlesions in the mouth of the other partner.

Humping, scissoring (skin-to-skin contact, from genitals to another’s  genitals)

• Common transmission : Trichomoniasis (parasitic vaginitis), Herpes type 1 and 2, Syphilis, HPV (warts)
• Uncommon transmission : Chlamydia, Gonorrhea, Hepatitis B and C, HIV

Using your hands or fingers (to stimulate the genitals, anus or nipples, without exchanging fluid)

• • Uncommon transmission : Herpes (HSV), Syphilis, Hepatitis B, HPV (warts), Shigellosis (if fingers come in contact with the mouth following anal penetration)
  • Impossible transmission : Chlamydia, Gonorrhea, Hepatitis C, HIV

• When no glove is used, always use the same hand for masturbation, and the other hand for stimulating your partner to avoid the exchange of fluids.

• It is important to wash your hands before touching the vaginal and anal areas. 

• It is also recommended to cut your nails in order to reduce the risk of micro-lesions on the skin.

Giving or receiving cunnilingus (stimulating the clitoris and vulva with the mouth and tongue)

• • Common transmission : Herpes type 1, HPV (warts), Syphilis
  • Uncommon transmission : Chlamydia, Gonorrhea, Hepatitis B, Herpes type 2, HIV 
  • Impossible transmission : Hepatitis C

• To avoid micro-lesions in the mouth, it is advisable to avoid brushing and flossing your teeth at least one hour before one hour after oral sex (cunnilingus, anilingus or fellatio).

Sharing sex toys (without cleaning them or using protection, with exchange of bodily fluids)

• • Common transmission : HPV (warts), Herpes (HSV)
  • Uncommon transmission : Chlamydia, Gonorrhea, Hepatitis B, Syphilis, HIV
  • Impossible transmission : Hepatitis C

• To properly clean and care for your sex toys, it is important to check the manufacturer’s instructions when you buy your toys in order to use the most appropriate products for the material of the toy. 

Some sex practices don’t involve genitals, fluid exchange, and so, no STI transmission risks, for instance : non genital massages, cuddles, some kink/BDSM practices (clothing, roleplay, feetplay), sexting, striptease, reading erotic stories, exchanging nudes, watching your partner masturbate, humping with clothes on, etc.

Condoms (internal, external and ones for fingers), dental dams and gloves are some of the best tools available to protect against STIs. Dental dams are especially useful for women having sex with other women. Notably, they can mediate transmission risks associated with menstrual blood. They can be purchased in sex shops, given in community organization or made at home form condoms. For more information :

• Dental Dam Use
• Everything You Need to Know About Using a Dental Dam

Getting tested regularly is also an important measure to take to prevent STIs risks. A lot of STIs can have little to no symptoms and you can easily catch one without noticing. Getting tested relatively often, just in case, is a good way to stay healthy.

I also want to say that getting an STI is not the end of the world, once detected STIs are usually very easy to treat (especially Chlamydia, Gonorrhea and Syphilis). Those who cannot be cured can still be treated with medication (antivirals) to reduce the frequency and intensity of symptoms and to reduce (or eliminate) the possibility of transmitting them, like HIV or Herpes. 

For more details, I would warmly recommend this very cool guide (unfortunately only in french, but translatable with google translate), which was a huge inspiration for this answer.

Let us know if you have more questions, we’d be happy to help!

Take care, and have fun,

Maxime, peer support agent for AlterHeros

Iel/they/them, accords neutres