Lambskin condoms aren’t actually made from true lambskin. They’re made from lamb cecum, which is the pouch located at the beginning of a lamb’s large intestine. These have been around for longer than you might expect.

Condoms made from the bladders and intestines of lambs and other animals have been around for thousands of years. They are often referred to as “natural skin condoms,” but the correct name for this type of condom is “natural membrane condom.”

Despite their ability to prevent pregnancy and provide a natural and more intimate feel, lambskin condoms began to lose popularity after the invention of latex condoms in the 1920s.

Sales of lambskin condoms increased again in the 1980s after the release of the Surgeon General’s report on AIDS. This was short-lived, as natural membrane condoms were found to be less effective in the spread of sexually transmitted infections (STIs).

Here is a brief rundown of how lambskin condoms compare to latex condoms:

  • Latex condoms are far more common and readily available than lambskin condoms. Approximately 80 percent of the condoms made in the United States are latex condoms. Natural membrane condoms account for just 5 percent.
  • Lambskin condoms seem to provide increased sensitivity and feel more natural than latex condoms. They’re also thought to transmit body heat better.
  • Lambskin condoms are an alternative to latex condoms for people with latex allergies.
  • Condoms, including lambskin condoms, are 98 percent effective in the prevention of pregnancy when used correctly. Improper use drops the effectiveness to around 85 percent.
  • Lambskin condoms are considerably more expensive than latex condoms.
  • Lambskin condoms are biodegradable. Latex is also biodegradable, but most latex condoms contain other materials besides latex.
  • Lambskin condoms can be used with all types of lubricants, including oil-based ones, which can’t be used with latex.
  • Natural membrane condoms are not recommended for the prevention of STIs and HIV, according to the Centers for Disease Control and Prevention (CDC).

A condom provides a barrier that keeps semen, vaginal fluids, and blood from passing from one partner to another during intercourse. This helps prevent pregnancy as well as the transmission of viruses and bacteria that can cause HIV and STIs.

Lambskin condoms are used just like other types of condoms and are worn over the penis. They protect against pregnancy by preventing the passing of sperm, but they don’t protect against the spread of viruses.

This is because natural membrane condoms contain tiny pores that, while small enough to block sperm, are big enough to allow virus leakage, according to a number of studies. These pores can be up to 1,500 nanometers (nm) in diameter, which is more than 10 times the diameter of HIV and more than 25 times the diameter of hepatitis B virus (HBV).

To prevent the spread of HIV and other STIs, latex condoms are recommended. If you’re allergic to latex, there are alternatives available:

  • Condoms made from plastic (such as polyurethane condoms) protect against both pregnancy and STIs. Plastic condoms break more often than latex; using a water- or silicone-based lubricant can help prevent breakage.
  • Condoms made from synthetic rubber (such as polyisoprene condoms) protect against both pregnancy and STIs.

Condoms are most effective when used correctly. While most types are applied in the same general manner, always read the instructions on the packaging to ensure proper use.

Lambskin condoms may be an option for those who are only concerned about preventing pregnancy, such as people in committed relationships who have tested negative for STIs.

If you’re allergic to latex, better options exist to lambskin condoms. For example, polyurethane condoms, unlike lambskin condoms, can also prevent the spread of STIs and HIV.