Dental dams come up constantly in STI-prevention advice — including our own STI prevention guide and oral sex guide — but rarely with actual instructions on how to use one. Here's the practical version.
What it is
A thin sheet of latex or polyurethane placed over the vulva or anus during oral sex, creating a barrier that reduces STI transmission risk the same way a condom does for penetrative sex — reducing risk significantly, not to zero, the same caveat that applies to any barrier method.
How to actually use one
- Place it flat over the area being orally stimulated, covering the relevant skin before any contact begins.
- Hold it in place — with hands, or some people use a small amount of lubricant on the body side to help it stay put.
- Use one side only, once. Don't flip it over mid-session and don't reuse it for a second session — the same single-use logic as a condom.
- Water-based lubricant on the receiving side can increase sensation for the person being stimulated, similar to how lube enhances other kinds of contact.
Making one from a condom
If a purpose-made dam isn't on hand, an unrolled condom can work as a substitute: cut off the closed tip and the ring at the open end, then cut down one side lengthwise to unroll it into a flat sheet. Use a non-lubricated condom or one with water- or silicone-based lubricant only — avoid anything oil-based, for the same reason it's avoided with condoms generally, covered in our condom guide.
Why they're less commonly used than condoms
Mostly unfamiliarity and lower availability, not impracticality — they're less commonly stocked and less commonly discussed than condoms, which means a lot of people simply don't know they exist as an option or how to use one, rather than having tried and rejected them.
Frequently asked questions
Can you actually make a dental dam from a condom?
Yes — cut off the tip and the closed end of an unrolled, non-lubricated (or water/silicone-lubricated) condom, then cut down one side to unroll it into a flat sheet. It's a genuinely common improvised option when a purpose-made dam isn't on hand.
Can a dental dam be reused or flipped over?
No — use one side once, for one session, then discard it, the same single-use logic as a condom. Flipping it over or reusing it defeats the purpose, since fluid from one side can end up on the other.
Why don't more people use them?
Mostly unfamiliarity and availability — they're less commonly stocked than condoms and less commonly discussed, not because they're impractical to use once someone actually knows how.
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