Most condoms are made from natural rubber latex, a milky fluid harvested from rubber trees. But latex isn’t the only option. Condoms also come in polyurethane, polyisoprene, nitrile, and natural animal membrane, each with distinct properties that affect thickness, sensation, allergen risk, and protection against sexually transmitted infections.
Natural Rubber Latex
Latex condoms are the most widely available and most studied type. The base material is natural rubber latex, which is processed and shaped into a thin film typically 0.070 to 0.080 mm thick. During manufacturing, the rubber undergoes vulcanization, a chemical process that uses sulfur to create cross-links between rubber molecules. These cross-links give the condom its elasticity and strength, allowing it to stretch significantly without tearing.
The formulation isn’t pure rubber. Manufacturers add antioxidants at roughly 0.5 to 2 parts per hundred of dry rubber to slow degradation. Without them, exposure to air, heat, and light would break down the sulfur cross-links over time, weakening the material. This is why latex condoms have expiration dates and shouldn’t be stored in wallets or glove compartments where heat accelerates that breakdown.
One manufacturing detail that surprises many people: most latex condoms use casein, a protein derived from milk, during production. Casein acts as a smoothing agent that helps the latex form an even film. This makes standard latex condoms unsuitable for people following a strict vegan lifestyle, though some brands now use plant-based alternatives in place of casein.
Latex condoms provide an effective barrier against both pregnancy and STIs, including HIV and hepatitis B. Their main drawback is that the proteins naturally present in rubber latex trigger allergic reactions in some people, ranging from mild skin irritation to more serious responses.
Polyurethane
Polyurethane condoms are made from a synthetic plastic polymer rather than rubber. The biggest practical difference is thickness: polyurethane can be manufactured with walls as thin as 0.035 to 0.040 mm, roughly half the thickness of a standard latex condom. That thinner wall is one reason some people report better sensation and heat transfer during use.
Because polyurethane is a plastic rather than an elastic material, these condoms don’t stretch the way latex does. They fit somewhat more loosely and are more prone to slipping if not used with adequate lubricant. Breakage rates in controlled studies have been slightly higher than latex. On the other hand, polyurethane is compatible with both water-based and oil-based lubricants, while oil breaks down latex. It also contains none of the plant proteins that cause latex allergies, making it a reliable alternative for people with that sensitivity.
Polyurethane provides a full barrier against sperm, bacteria, and viruses.
Polyisoprene (Synthetic Rubber)
Polyisoprene is essentially a lab-made version of the same molecule found in natural rubber. The key difference is that synthetic polyisoprene doesn’t contain the proteins in natural latex that trigger allergic reactions. If you’ve been told you have a latex allergy but prefer the stretchy feel of rubber over the stiffer feel of polyurethane, polyisoprene condoms are designed for exactly that situation.
In terms of thickness and elasticity, polyisoprene condoms feel very similar to latex. They stretch and conform in the same way. Like latex, they should only be used with water-based or silicone-based lubricants, since oil-based products degrade the material. They provide full STI and pregnancy protection.
Lambskin (Natural Membrane)
So-called “lambskin” condoms aren’t made from skin at all. They’re made from lamb cecum, the pouch at the beginning of a lamb’s large intestine. This natural animal membrane has been used as a barrier method for centuries, and some people prefer the sensation because the thin tissue conducts body heat more naturally than any synthetic material.
There’s a significant limitation, though. The membrane contains tiny naturally occurring pores that can be up to 1,500 nanometers in diameter. Sperm cells are far too large to pass through these pores, so lambskin condoms are effective for pregnancy prevention. But viruses are much smaller. Those 1,500-nanometer pores are more than 10 times the diameter of HIV and more than 25 times the diameter of the hepatitis B virus. This means lambskin condoms do not reliably protect against STIs.
If pregnancy prevention is your only goal and STI risk isn’t a concern, lambskin is a viable option. For STI protection, you need a synthetic or latex barrier.
Nitrile (Internal Condoms)
Internal condoms, sometimes called female condoms, are typically made from nitrile, a synthetic rubber commonly used in medical gloves. The FC2 internal condom, the most widely available version approved by the FDA, uses a nitrile sheath with a nitrile outer ring and a polyurethane inner ring for structure. An earlier version used polyurethane throughout, but the switch to nitrile reduced manufacturing costs while maintaining barrier effectiveness.
Nitrile is latex-free, so it works for people with latex allergies. It’s also compatible with both water-based and oil-based lubricants. Internal condoms are the only option that gives the receptive partner direct control over barrier use.
How Material Affects Your Choice
The material a condom is made from determines four things that matter in practice: allergy safety, STI protection, compatible lubricants, and how it feels.
- Latex allergy: If you have one, polyisoprene, polyurethane, and nitrile are all safe alternatives. Lambskin is also latex-free but doesn’t protect against STIs.
- STI protection: Latex, polyisoprene, polyurethane, and nitrile all block viruses and bacteria. Lambskin does not.
- Oil-based lubricants: Only polyurethane and nitrile hold up against oil. Latex and polyisoprene will degrade.
- Sensation and thickness: Polyurethane is the thinnest synthetic option. Lambskin offers the most natural heat transfer. Latex and polyisoprene fall in the middle.
Condoms also contain a lubricant coating, which is typically silicone-based or water-based, and many include a spermicide or are sold unlubricated for people who prefer to choose their own. The base material, however, is what determines the structural properties and safety profile of any condom you pick up.