Do condoms protect against all STIs?

What condoms work for and what they don't

Male condoms are the only form of contraception that both prevent pregnancy and protect against some STIs. Most condoms are made of latex, but polyurethane or polyisoprene condoms are available for those who are sensitive to latex. Free condoms are available at contraception clinics sexual health clinics and some GP surgeries.


How do condoms work?

Condoms provide a ‘barrier’ which is 98% effective in preventing pregnancy. When used correctly during vaginal, anal and oral sex, they are also effective in protecting against STIs. Male condoms are worn on the penis to collect semen and prevent it being transferred into the vagina, stopping sperm from meeting an egg.

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Do condoms protect against all STIs?

Condoms are 98% effective in protecting against STIs which are spread through semen or vaginal fluids, including chlamydia, gonorrhoea and hepatitis B. However, chlamydia and gonorrhoea can be transmitted through oral sex as well, because they are bacterial infections spread via the mucous membranes present at all openings to the body. Although rare, it is also possible for hepatitis C to be spread through sex, and wearing a condom greatly reduces the chance of transmission.

Condoms will not protect against STIs which are transferable via skin-to-skin contact, such as herpes, HPV (which sometimes results in genital warts) and syphilis. Wearing a condom reduces the likelihood of transmission, but if these infections are present in the groin area not covered by the condom, they can be passed on regardless. Pubic lice, or crabs, is another one you may have heard of, although it is not so common nowadays as people tend to groom more. Since lice live and lay eggs in pubic hair, a condom will do nothing to prevent their spread.


Do condoms protect against HIV?

Consistent and correct use of condoms has proven effective in preventing sexual transmission of HIV, the virus that causes AIDS. HIV is spread through blood, semen, pre-seminal fluids rectal fluids and vaginal fluids, and laboratory studies have been conducted to ensure that the materials used to make condoms (latex, polyurethane, and polyisoprene) do not let the HIV virus pass through them.

The bottom line of STIs is that if you are sexually active, you should get checked regularly for infection, even if you practice safe sex and use a condom.

How to apply a condom

Most cases of condom failure are due to mechanical errors, such as breakage, slippage or improper application. It is therefore vital to make sure you know how to apply a condom correctly whether you are male or female.

  • Remove the condom from the packet carefully, being careful not to tear it

  • Check the condom for damage before and after use. Even the smallest tear can allow sperm to pass through.

  • Place the condom on the tip of the penis and squeeze the small teat at the end to make sure no air is trapped. Roll the condom down to the base of the penis.

  • If you have difficulty at this stage, the condom may be inside out. It so, throw it away and try again with a new one, as it might have sperm on it.

  • After ejaculating, a man must withdraw while the penis is still erect to prevent sperm leaking into the vagina. Holding the condom at the base while doing this will prevent it from slipping off.

  • Remove the condom, being careful not to spill any semen, and discard in a bin, not the toilet.

If the penis comes into contact with the vagina before a condom has been put on or after it has been taken off, and STI may still be transferred, so you may wish to take emergency contraception and an STI test. Semen can come out of the penis before full ejaculation. Similarly, if a condom slips off during sex, you can be at risk of STIs or pregnancy.



NHS - Condoms -


CDC - Condom Failure:

CATIE - COndoms for the prevention of HIV and hepatitis C transmission:

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