Condoms are thin, balloon-like sheaths made of latex, natural membrane, lambskin or polyurethane. Condoms are designed to cover the entire penis, including the opening at the tip and the shaft.

Condoms are available with or without a spermicidal (sperm-killing) coating that further decreases the chance of pregnancy and provides extra protection should the condom tear.

Condoms are about 85% effective in preventing pregnancy when used in a typical way. This means that if 100 couples use condoms for one year as their only method of preventing pregnancy, 15 of the women will become pregnant.

The effectiveness of condoms may be as high as 95% if condoms are used perfectly, meaning that a couple uses condoms consistently and correctly, and that there is no accidental slippage or breakage. Forgetting to use the condom or not using it correctly is the most common reason for failure and unplanned pregnancy.

If a condom is used with a spermicide, the effectiveness may be as high as 95%.

Advantages

• Use of a condom does not interfere with a man's or a woman's chance of conceiving a child in the future. Pregnancy is possible whenever sexual intercourse occurs without a condom.
• Condoms provide a "two-for-one" benefit because, in addition to preventing pregnancy, they also help to decrease the risk of sexually transmitted diseases (STDs).
• Latex condoms are the only barrier method proven to prevent HIV. They also are proven to help to reduce the risk of exposure and spread of other sexually transmitted bacteria and viruses such as chlamydia, gonorrhea and human papilloma virus. However, even when a man uses a condom, these viruses may infect areas of the genital skin that are in direct contact during sexual intercourse, such as the male's scrotum and the female's labia.
• Unlike latex condoms, natural membrane or lambskin condoms do not provide a high level of protection against STDs, although they do protect against pregnancy. Polyurethane condoms may decrease the spread of STDs, but more studies are needed before this can be confirmed.

Disadvantages

• Condoms need to be put on correctly before each act of sexual intercourse.
• A new condom must be used each time you have intercourse.
• Latex condoms for men can be combined with every other method of reversible and permanent birth control with one exception: They should not be used together with female condoms because either or both can dislodge and slip off.
• Side effects from condoms are rare, but some people may have allergies to latex or skin irritation due to chemical spermicides.