How do you use a dental dam?
A dental dam is a thin latex or polyurethane sheet placed flat over the vulva or anus during oral sex. Use a new one every time, put it in place before any mouth-to-skin contact, keep it there until you finish, and add water-based or silicone lube on the skin side if you like. Never flip it over or reuse it.
A dental dam is a thin, flexible square that sits between the mouth and a partner's vulva or anus during oral sex, lowering the chance of passing on an STI. Most are latex or polyurethane (CDC, 2024), and Planned Parenthood also mentions nitrile and neoprene. Cleveland Clinic notes that dental dams reduce the risk of STIs such as oral HPV (Cleveland Clinic, 2025).
Step by step: check the expiry date and look for tears; open the packet carefully so you do not rip the dam; if you like, add a little water-based or silicone lube to the side that will touch the skin; lay it flat over the vulva or anus before there is any mouth-to-skin contact; hold it gently in place, since it does not need stretching or pressing tight; keep it there until you finish; then throw it in the bin (CDC, 2024; Planned Parenthood, 2025).
The common mistakes are flipping the dam over to use the other side, reusing it, stretching it, which can tear it, using oil-based products such as baby oil, lotion or petroleum jelly, which can break it, and using nonoxynol-9, a spermicide that can cause irritation (CDC, 2024; Planned Parenthood, 2025). Use a fresh dam for each partner.
No dam to hand? CDC and Planned Parenthood both describe making one from an external condom: unroll it, cut off the tip and the bottom ring, cut down one side and open it out flat. Make sure the condom is latex or polyurethane, not lambskin (CDC, 2024). Planned Parenthood notes that an internal condom can be cut open the same way.
Store dams somewhere cool and dry, away from sunlight and sharp objects, and throw away any that are expired, damaged, sticky, dried out or discoloured (Planned Parenthood, 2025). Put used dams in the bin, not the toilet (CDC, 2024). Dams can be harder to find than condoms: they are sold online and in some pharmacies and sex shops, and some sexual health clinics give them out (Planned Parenthood). The JoinTheSwing guides to dental dams and to condom types cover barriers in more depth. This answer is general information, not medical advice.
How this answer was checked.
Written by JoinTheSwing editorial and not reviewed by a clinician; general information, not medical advice. The steps and the condom-to-dam method follow the CDC and Planned Parenthood instructions below, opened on the review date; improvised materials those sources do not describe are left out.
- CDC, April 3, 2024
How to Use a Dental Dam (opens in a new tab)
Latex or polyurethane sheets for oral sex on the vagina or anus: a new dam every time, check the date and for tears, on before oral sex starts and kept on until the end, water- or silicone-based lube, no stretching, no nonoxynol-9, no oil-based products, no reusing; how to cut a latex or polyurethane condom into a dam.
- Planned Parenthood, June 5, 2025
What's a dental dam? (opens in a new tab)
A thin square of latex, polyurethane, nitrile or neoprene; place it before any mouth-to-skin contact and hold it gently in place; water-based or silicone lube on the side touching the skin; never flip it over or reuse it; throw out expired, damaged or sticky dams; a condom can be turned into a dam.
- Planned Parenthood
Condoms (opens in a new tab)
Latex, plastic (polyurethane, nitrile, polyisoprene) and lambskin condoms; oil damages latex, and oil-based lube works with plastic condoms except polyisoprene; lambskin only helps prevent pregnancy; condoms work very well against fluid-borne STIs and somewhat less well against skin-to-skin STIs; avoid flavoured products for vaginal or anal sex; a condom cut open makes a dam.
- Cleveland Clinic, updated November 18, 2025
Condoms (opens in a new tab)
Latex, plastic (polyurethane, polyisoprene, nitrile) and natural-skin materials; oil-based lube breaks latex and polyisoprene; natural-skin condoms prevent pregnancy but are not recommended for STI prevention; most failures are human error, including one condom used with more than one partner during group sex; condoms generally last one to five years; store cool and dry, not in a wallet; spermicide-lubricated condoms can cause UTIs.