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Sexually transmitted infections

This section contains a brief explanation of how common sexually transmitted infections (STIs) are passed on, their symptoms and their treatment.

STIs can be caused by bacteria, viruses or parasites. More common STIs include:

  • Chlamydia, including Lymphogranuloma Venereum (LGV)
  • genital and anal warts (caused by the human papillomavirus, or HPV). An HPV vaccine is available for girls aged 12 and 13. It will be considered for boys following a two-year research project.. It is recommended for men who have sex with men aged 45 and under. The vaccine is likely to become available to men who have sex with men through sexual health clinics during 2016, subject to funding.
  • gonorrhoea
  • hepatitis A, B and C (see Transmission and prevention of STIs, below, for more information)
  • herpes (caused by the herpes simplex virus, or HSV). This can cause both oral (on the mouth) and genital infection
  • syphilis
  • parasites such as pubic lice (sometimes called crabs) and scabies
  • shigellosis, an illness caused by the bacteria Shigella, and other illnesses that cause diarrhoea
  • trichomoniasis, an infection caused by a very small parasite.

Common symptoms

There are some common symptoms of STIs. These include:

  • a discharge from your vagina, penis or anus. This may be discoloured – for example, milky, yellowish or like mucus – or may have blood in it
  • pain or a burning feeling when you urinate (pee) or needing to urinate more often than usual
  • pain while you are having sex
  • pain or swelling around your anus or testicles
  • generally feeling unwell
  • for herpes, numbness, itching and tingling, followed by bumps that become small, fluid-filled blisters
  • for syphilis, small sores, spots or ulcers on the penis or around the mouth, vagina or anus
  • for hepatitis A, B and C, symptoms can include jaundice (a yellowing of skin and eyes), nausea and vomiting, and tiredness
  • for genital warts, lumps and bumps around the genital area and anus
  • diarrhoea with blood and pain.

However, many people have no symptoms at all when they first get an STI, or their symptoms are so mild they don’t notice them. Regular sexual health checks are important because they can diagnose STIs even if you have no symptoms. Many STIs can go on to cause serious, long-term health problems if they are not diagnosed and treated, including causing infertility. Hepatitis B and C can become chronic (long-term) conditions and lead to serious liver damage.


Bacterial infections and trichomoniasis can be cured with antibiotics. These may be given as tablets or by injections, depending on the STI you have.

Antiviral drugs can be used to treat some viral infections. Herpes cannot be cured and the virus stays in nerve cells for life, although most of the time it may not cause symptoms. You may have flare-ups from time to time, especially if you have a weakened immune system. Your immune system may cure HPV, the genital warts virus, but this may take a long time and for some people never happens.

Lotions can clear infestations of parasites such as scabies or pubic lice, along with washing clothing, towels and bedding at high temperatures.

It is important to finish the whole course of any drugs prescribed and to go to any follow-up appointments you are advised to have. This will ensure you get the correct treatment and are completely cured of the STI, if that is possible.

Any sexual partners you have had since the time you may have been infected should also go for a sexual health check, as they may also need to be treated.

You can read more about these STIs, their transmission, prevention, diagnosis and treatment, in NAM’s factsheets.

Transmission and prevention of STIs

STIs can be transmitted through anal, oral and vaginal sex, and by sharing sex toys. Some can also be passed on through rimming (mouth-to-anus contact), kissing or other close physical contact. Parasites can be passed on by sharing towels or bedding. Some STIs (including hepatitis A) and other infections (for example, gut infections such as giardia) can be caused by contact with infected faeces (excrement, shit), such as during rimming or fisting. Hepatitis A can also be transmitted through contact with infected faeces in contaminated food, for example, shellfish.

Hepatitis B is passed on by contact with the blood, semen, saliva, or vaginal fluids of a person with hepatitis B. It is easily passed on during sex without a condom and from a mother to her baby during delivery. It is many times more infectious than HIV.

Hepatitis C is normally passed on through blood-to-blood contact. Since 2000, there have been increasing numbers of cases of hepatitis C passed on through sex among gay men having anal sex without using condoms. Other factors that seem to be associated with sexual transmission of hepatitis C are group sex, injecting or snorting drugs, anal administration of drugs and the presence in either person of other STIs, especially syphilis or LGV infection.

Using condoms during anal or vaginal sex, using a condom or dental dam for oral sex, and not sharing sex toys can protect you against most STIs. If you are fisting, to protect yourself against hepatitis C, wear latex gloves and do not share pots of lubricant.. With some STIs, using a condom or dental dam will reduce the risk of infection, but not protect you completely. See part 2 for more information on using male and female condoms and other safer-sex information.

There are vaccines available for hepatitis A and B. Unless they have a natural immunity to these viruses, people with HIV are recommended to be vaccinated against them. You may have these vaccinations at your GP surgery rather than your HIV clinic. If your immune system becomes weaker, you may need to have your immunity level checked.

If you have been diagnosed with an STI, or are having a flare-up of herpes symptoms, you may be advised not to have sex (even with a condom) until any treatment is finished, and sometimes for a while after that.

HIV & sex

Published January 2016

Last reviewed January 2016

Next review January 2019

Contact NAM to find out more about the scientific research and information used to produce this booklet.

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.