Lay a new dental dam flat over the vulva or anus before any oral contact, hold it in place until finished, and throw it away after one use.
A dental dam is a thin latex or polyurethane sheet that acts as a barrier during oral sex. It covers the vulva or anus, blocking the skin-to-skin and fluid contact that passes many sexually transmitted infections (STIs).
Here is exactly how to use one, what to pair it with, and the mistakes that quietly ruin its protection.
What a Dental Dam Covers — and What It Doesn’t
A dental dam protects oral-vaginal and oral-anal contact. It is not designed for oral sex on a penis, and it does not prevent pregnancy.
The barrier stops the mouth from touching the vulva or anus directly, reducing exposure to infections spread through oral contact. The CDC lists dental dams as one option for safer oral sex; Cleveland Clinic notes the dam creates a physical wall between mouth and genitals or anus.
Two limits matter. A dam does not replace a condom for penetrative sex — they cover different contact. And reducing risk is not eliminating it: used correctly and consistently, a dam lowers STI exposure but is not a guarantee.
Condoms offer a cheaper, easier-to-find barrier for oral sex on a penis. Our review of the best condoms for oral walks through the options we tested.
How Do You Use a Dental Dam Step by Step?
Open a fresh dam, lay it flat over the entire vulva or anus before any contact, hold it in place, and keep it on until you finish.
- Check the package and expiration date. Inspect the dam for tears, holes, or defects.
- Open the package carefully — fingernails and teeth can nick the material.
- Lay the dam flat over the vulva or anus, covering the whole area.
- Hold it in place so it does not slip or fold.
- Keep it on for the entire act. Do not flip it over or turn it inside out.
- Throw it away after one use. One dam, one use.
The dam should stay flat, stay put, and never touch skin-to-skin. If it slips or tears, stop and start again with a fresh one.
Which Lubricant Is Safe With a Dental Dam?
Use water-based or silicone-based lubricant. Oil-based products — baby oil, lotion, petroleum jelly, cooking oil — can weaken and break latex dams. A little lubricant on the genital side reduces friction and helps the dam resist tearing.
- Latex dams — water-based or silicone-based lubricant only. Oil-based products degrade latex.
- Polyurethane dams — water-based, silicone-based, and oil-based lubricants are all compatible.
Do not use products containing nonoxynol-9. It can cause irritation, which increases risk rather than lowering it.
| Situation | What to Do | Why It Matters |
|---|---|---|
| Dam slips during use | Stop and replace with a new dam | Exposed skin removes the barrier protection |
| Dam tears or has a hole | Discard it and start with a fresh one | A break defeats the entire purpose |
| Switching from anal to vaginal contact | Use a new dam | Never share one dam between the two |
| Latex dam plus baby oil or lotion | Switch to water- or silicone-based lube | Oil breaks down latex |
| Dam has expired | Throw it out, use a new one | Old material can be weak or brittle |
| Finished with the dam | Wrap it and put it in the trash | Dams do not flush; they clog plumbing |
| Reaching for the same dam again | Use a new one instead | Reusing or flipping a dam removes protection |
Cleveland Clinic and Alberta Health Services both list these same rules on reuse, flipping, and lubricant choice. CDC guidance on dental dams covers the basic barrier and STI-reduction points.
Common Mistakes That Weaken Protection
Most failures come down to flipping, reusing, or storing the dam wrong.
- Flipping it over: once a side has touched the genitals or anus, it should never touch the mouth.
- Reusing it: a dam is single-use. Washable versions exist, but a used one should still be thrown out after the act.
- Stretching it: stretching thins the material and can create weak spots.
- Sharing between acts: going from anal to vaginal contact without a fresh dam moves bacteria and fluids where they should not go.
- Flushing it: dental dams belong in the trash, not the toilet.
- Storing it badly: heat and moisture degrade latex. Keep dams in a cool, dry place.
Dams are sold in drugstores and online and are inexpensive per use — the real barrier is remembering to restock before you need one.
Common Questions
Does a dental dam prevent pregnancy?
No. It blocks mouth-to-vulva or mouth-to-anus contact, so it reduces STI exposure. It does not cover the vagina during penetration and does nothing to stop sperm from reaching an egg. If pregnancy is a concern, use a separate method such as condoms or another contraceptive alongside it.
Can you use a dental dam for oral sex on a penis?
Not effectively. A dental dam is designed to cover the vulva or anus, not the penis, and it does not stay in place well during that kind of contact. For oral sex on a penis, a standard condom is the better barrier and far easier to find. The two do different jobs.
How long can you keep a dental dam before it expires?
Follow the expiration date printed on the package. Latex and polyurethane break down over time, so an expired dam may be weak or brittle. Store it in a cool, dry place away from heat and sunlight. Check the date and inspect the material for tears every time before use.
Sources
- CDC. “Dental Dam.” U.S. public health guidance on dental dam use for STI reduction.
- Cleveland Clinic. “Dental Dam.” Covers use steps, lubricant compatibility, and common mistakes.
- Alberta Health Services. “Dental Dams: Instructions.” Step-by-step instructions and single-use rules.