Sexually transmitted infections (STIs)
Your health expert: Dr Naveen Puri, Associate Clinical Director, Bupa Health Clinics
Content editor review by Liz Woolf, December 2021
Next review due December 2024
Sexually transmitted infections (STIs) spread during sexual activity. They can be passed on through unprotected vaginal, anal, or oral sex. They can also be spread by sharing sex toys.
STIs are most common in people under 25. But anyone who is sexually active can catch one.
Symptoms of sexually transmitted infections
STI symptoms vary depending on which infection you have. They may also vary between people. STIs don’t always cause symptoms, so you may not realise you have one.
STI symptoms can include:
- discharge from your vagina, penis or anus, which may be thicker than usual, coloured or smelly
- stinging, pain or burning when you pee, or during or after sex
- itching, rashes, lumps, sores or blisters around your vagina, penis or anus
- bleeding between periods or after sex
- pain or swelling of your testicles or epididymis (the tube down the back of each testicle)
- pain in your lower tummy (abdomen)
- sores around your mouth or a sore throat if you are infected through oral sex
- rashes and skin changes across the body (for some STIs)
Even without symptoms, you can pass an STI to someone else. So, it's important to get tested if you think you’re at risk. Go to your GP or a sexual health clinic if you:
- have had new sexual contact without using a condom or barrier contraceptive
- are planning to have unprotected sex
Some STIs can lead to more serious health problems if not treated, including infertility.
Sometimes STIs are diagnosed through tests for a urine infection or a vaginal infection.
Diagnosis of STIs
If you think you’re at risk of an STI, you can go to a sexual health or genito-urinary medicine (GUM) clinic. If you can’t go to a sexual health clinic, call your GP for advice. Some GP practices also offer specialist sexual health services, so it’s worth checking.
It’s best to go to a sexual health clinic for a diagnosis, because the doctors and nurses there are specially trained to diagnose and treat STIs and have specialised equipment. They can also help to anonymously trace your sexual contacts, in case they need testing too.
All visits to sexual health clinics are confidential. You don't have to give your real name and may have a number to identify you instead. Your details won't be sent to your GP unless you agree.
They will usually ask about:
- your medical history
- whether you’ve had STI symptoms or an STI before
- your current and recent sexual partners
- the types of sexual activities you practice
- the type of contraception you use
You usually need an examination to check for signs of infection. This may involve internal examinations of the vagina and cervix, anus (back passage) or throat. You may have swabs (samples) taken with a small, cotton bud, blood tests and urine tests. These shouldn’t hurt, but a swab or internal examination may be a bit uncomfortable.
If you're diagnosed with an STI, it's important your previous sexual partners know, so they can be tested. If necessary, they can get treatment and avoid passing the infection on. They may not have symptoms, so not realise they have an infection. If you don’t want to contact them, the clinic can contact them anonymously on your behalf.
There are home self-testing kits for some STIs, such as chlamydia, available online and from some pharmacies. Some are NHS-approved and available for free, while others you may have to pay for. Whether these self-tests are free may depend on where in the UK you live, and your age. You should only buy or order these tests from somewhere you trust. Because chlamydia often has no symptoms in women, pharmacies can supply free test kits to women as part of the National Chlamydia Screening Programme.
Concerned about STIs, or want to check your sexual health?
Concerned you have an STI, may have been exposed to one or just want to have a full screen, we offer a range of sexual health services.
What should I do if I think I've got an STI?
Accessing sexual health services | Talking about symptoms | Watch in 2 minutes
Bupa GP, Dr Naveen Puri, gives advice about talking to a doctor if you think you have a sexually transmitted infection (STI).
Hello, I'm Dr Naveen Puri, I'm one of the GPs at Bupa Health Clinics. Today I'd like to talk to you about presenting with problems that may be of a sexual health nature.
We know that people can often feel embarrassed talking about their sexual health for fear of judgement. Some shame or embarrassment may accompany your concerns, but please let me assure you, as doctors, we've heard it all before.
Any concerns you have we've come across on many occasions and we're here to offer you a judgement and pain-free service in as far as we possibly can.
It's in your interest to tell us all your symptoms so we can help you get better and prevent any consequences that might come into play if you don't seek out help for your condition sooner rather than later.
We know for example some untreated infections can lead to problems with fertility. They can lead to pelvic inflammatory diseases or severe infection of the testicles so rather than you getting worse and your symptoms progressing to something more serious, let us know sooner rather than later so we can help you.
In terms of accessing sexual health services, there are many ways young can do this. We offer the services within Bupa and you can also access the services within the NHS as well.
Some people like to go to a walk-in service where they can turn up and wait for an appointment, others prefer to book an appointment in advance and that way they know when they're going to be seen and arrive at the clinic in an appropriate time frame as well.
I'd also say there's nothing to be ashamed or embarrassed about, we have seen and heard all of the symptoms before.
The kind of things people come to us with range from pain during intercourse, a discharge, either from the penis or the vagina, or other symptoms such as abdominal pain, a sore throat or other things that could occur after an infection is acquired.
So, whatever it might be, let us do the detective work for you. Let us know what your symptoms are.
Feel free to bring someone with you if you'd like, write your problems down so you can discuss them with us. Or use the language you want to as well, we don't expect you to know the medical terms for things we can help you with that as well.
And hopefully, together we can get to the bottom of whatever your issue is, and we can provide you with an appropriate treatment or cure if that is available as well.
Causes of STIs
STIs are caused by bacteria, viruses or parasites. You can catch these infections during sex, genital contact, sharing sex toys and oral sex with an infected person.
Some blood-borne viruses can be passed on during sex, contact with bodily fluids or through drug users sharing contaminated needles and syringes.
Preventing STIs
Practising safer sex lowers your risk of catching or passing on an STI. This means:
- using condoms for vaginal, anal and oral sex
- both you and a new partner getting tested for STIs before you have sex
- not sharing sex toys, or washing them before and after anyone else uses them
- getting vaccinated against certain STIs such as hepatitis A and B if you’re at risk (if you’re not sure, ask your doctor or nurse)
- asking your doctor or sexual health clinic about tablets for preventing HIV (PrEP)
Types of STIs
Many different infections can be passed on through sex. The commonest in the UK are chlamydia, genital warts, gonorrhoea and genital herpes.
Chlamydia
Chlamydia is the commonest STI, particularly in people aged under 25. Many people infected with chlamydia don’t have any signs or symptoms. If you do get symptoms, they can appear up to three weeks after you’re infected. You may have:
- cloudy white, yellow or green discharge from your vagina, penis, or anus
- vaginal, testicular or tummy pain
- vaginal bleeding between periods or after sex
- a sore throat, sometimes, if the infection has been passed on during oral sex (although infection in this way usually has no symptoms)
Chlamydia infection can also cause a condition called lymphogranuloma venereum or LGV. This is nearly always found in men who have sex with men. It can cause painful inflammation of the back passage (rectum), a discharge and swollen lymph glands (lymph nodes).
It’s important to have any chlamydia infection treated promptly with antibiotics. If it isn’t treated, it can spread internally and lead to more serious problems, such as pelvic inflammatory disease and infertility in women, or permanent rectal damage in cases of LGV.
Genital warts
These are caused by the human papilloma virus (HPV). In the UK, everyone aged 12 to 13 is offered the HPV vaccine, as part of the National HPV Vaccination Programme. The vaccine protects against the four strains (types) of HPV that cause cervical cancer and some strains that cause genital warts. A new version of this vaccine is being introduced between autumn 2021 and summer 2022, in the UK. This protects against the same four strains that cause cancer and a further five strains of HPV that cause genital warts.
Genital warts can appear on your penis, vagina or anus as small, smooth, round bumps, several larger bumps grouped together or small cauliflower-shaped bumps. They may be painful, burning or itchy. It can take a few weeks or months after you first come into contact with the virus for the warts to appear.
You can pass the HPV virus on, even if you don’t have any warts at the time. Using a condom reduces this risk but won’t fully protect your partner.
Genital warts often disappear on their own within a few months. But your doctor may suggest treatment, depending on where your warts are, how much they’re affecting you and whether you have other medical conditions. Removal may be with solutions or gels you apply yourself. Or you may have the warts frozen off (cryotherapy), laser treatment or surgery. Treatment doesn’t always work and may have to be repeated.
Genital herpes
Genital herpes is caused by herpes simplex viruses. These can cause cold sores around your mouth and genitals.
Many people have no symptoms. Or you may have burning or tingling in your vagina, penis or anus. Fluid-filled blisters or sores can develop around your vagina, cervix, penis or mouth if you’ve had oral sex. You may feel tired and unwell, have a high temperature (fever) or pain when peeing.
This first (primary) outbreak of genital herpes can last for up to four weeks if it isn’t treated. After your first infection, you may have flare-ups in the following months or years.
You can still pass the virus on to your partner if your skin looks normal. Using condoms can reduce the risk, but won’t protect your partner completely. You can also pass it on during oral sex.
Once you catch herpes, you have it for life, but flare-ups usually lessen as time goes on. For most people, they do eventually stop. During a flare-up, you can have antiviral medicines to help clear it up more quickly.
Gonorrhoea
Gonorrhoea is a common bacterial STI. Nine out of 10 men with gonorrhoea have symptoms. But around half of women don’t, so they can be infected and not know. If you do get symptoms, it can take up to 10 days after you’re infected for them to appear. They can include:
- a smelly or coloured discharge from your vagina or penis
- pain when you pee
- mild lower tummy pain or testicular pain, usually on one side
- anal itching, bleeding or discharge
- in some cases, a sore throat
Treatment is with antibiotics (either tablets or sometimes an injection, depending on the type of gonorrhoea). You shouldn’t have unprotected sex until you’ve both been tested and finished treatment at least seven days earlier. If not treated, gonorrhoea can cause serious long-term health problems including pelvic inflammatory disease and infertility in women, and painful joints (reactive arthritis).
Hepatitis
Hepatitis is a viral infection of your liver. You can catch hepatitis A, B or C through sexual contact or sharing contaminated needles when injecting drugs.
Up to seven in every 10 people with hepatitis B or C don’t have any symptoms. If you do have symptoms, they can begin any time from six weeks to six months after you’ve been infected.
Hepatitis A may also not cause symptoms, although they can appear after around six weeks and last for weeks or months.
Hepatitis symptoms can include:
- flu symptoms
- sickness and vomiting
- right-sided aching below your ribs
- yellowing skin and eyes (jaundice)
- itching
- darker pee and lighter-coloured poo
- aching joints
- weakness and lack of energy
Hepatitis A gets better on its own, although it can take months to get back to normal.
Although it can cause serious illness, most people with hepatitis B, and some with hepatitis C, get better without treatment. You’ll need regular blood tests and you may have antiviral medicines.
However, many acute hepatitis infections go away on their own without antiviral treatment. Some people develop chronic (long-term) hepatitis, increasing risk of liver cirrhosis or cancer.
You can be vaccinated against hepatitis A and B at a sexual health clinic if you are at high risk. If you think you’ve been exposed to hepatitis A or B and haven’t been vaccinated, go to a sexual health clinic as soon as possible. You can have an injection of the vaccine, sometimes with a protective injection (hepatitis A or B immunoglobulin). The hep B protection works best if you’re given it within 48 hours of being exposed to the hepatitis B virus. For hep A, you can have the protective injection up to two weeks after exposure.
There’s no vaccine for hepatitis C.
HIV
Human immunodeficiency virus (HIV) is the virus that causes AIDS. It can be passed on during sex or through contaminated needles or syringes.
Some people with HIV have no signs and symptoms when they first become infected. Or you may have flu-like symptoms up to six weeks after infection. Symptoms may include a high temperature, aches and pains, a sore throat, headaches and swollen glands. Over time, the HIV virus can weaken your immune system, increasing your risk of other infections and tumours.
There are treatments that can control the virus, called antiretrovirals. These reduce your risk of serious complications, including developing AIDS, and keep you well.
If you think you’ve been exposed to HIV, visit a sexual health clinic or Accident and Emergency (A&E) department as soon as possible. You can take a course of antiretroviral medicines (called post-exposure prophylaxis) to reduce your risk of infection. This works best the sooner you have it, but you can have it up to 72 hours after exposure to HIV.
Pubic lice
Pubic lice are tiny insects that live in coarse body hair, including pubic hair, chest hair, eyelashes and eyebrows. They are sometimes called ‘crabs’. They’re different to head lice but they can live on your head, so if you have them you need to check everywhere on your body where there’s hair.
Pubic lice are very hard to see. You may notice itchy red spots on your skin or brown eggs (nits) stuck to your body hair. You may also see brown-black powdery spots in your underwear from lice droppings.
Treatment is with insecticide lotions or shampoos. You use these over your whole body, including eyebrows, beard and other body hair. You repeat the treatment seven days later. Any sexual partners you’ve had in the previous 3 months need to check whether they’re infected.
Syphilis
Syphilis is a bacterial STI that has three stages: primary, secondary and tertiary.
The primary stage begins any time between nine and 90 days after you’re infected. You may have one or more ulcers, called chancres, on your skin (pronounced ‘kangker’). Because they are painless, you may not notice them. They can be anywhere on your body, but most often on the penis, anus, vagina, cervix, mouth or lips. They usually heal within six weeks.
The secondary stage usually begins around six weeks after your chancres have healed. But it may develop some months later. You may feel generally unwell with flu-like symptoms, swollen glands (lymph nodes) and a rash.
It’s very important to have treatment with antibiotics. This is usually given through an injection into a muscle of the bottom. If you don’t, you may develop the tertiary stage of the disease years later. This causes serious health problems, affecting many parts of your body including your nervous system, eyes and heart.
Yes, you should. STIs don’t always cause symptoms, but if left untreated, could get worse or cause serious health complications. Some can lead to infertility. And if you are infected, you could pass a STI on to someone else. Go to a sexual health or genito-urinary medicine (GUM) clinic.
Mostly, yes. There are some that you have for life once infected, but even then medicine can help to control the symptoms. These are generally the viral infections, such as herpes or HIV. You can also develop a chronic infection if you catch hepatitis.
Go to your doctor or a sexual health clinic. There is treatment that can help, even if it won’t get rid of the infection completely.
If you think you may have an STI, you should see a doctor, preferably at a sexual health clinic. Sexual health clinics are totally confidential and you don’t even have to give your own name. Many STIs cause similar symptoms and you really can’t get diagnosed online as you may need to have urine, blood or swab tests. It’s important to get treatment to avoid future health problems, to avoid passing on the infection.
Pelvic inflammatory disease
Pelvic inflammatory disease (PID) is inflammation of the upper part of a woman’s reproductive organs.
Vaginal thrush
Vaginal infections
You can get a vaginal infection if bacteria, fungi or viruses grow in and around your vagina.
What is chlamydia?
Chlamydia is one of the most common sexually transmitted infections (STIs) in the UK. Dr Naveen Puri answers some very common questions about chlamydia.
What is gonorrhoea?
Gonorrhoea is a type of sexually transmitted infection (STI). Alongside chlamydia, it is one of the most common STIs in the UK. Dr Naveen Puri explains more about this common STI.
What is syphilis?
Syphilis is a sexually transmitted infection (STI). Like other STIs, it can be passed on during unprotected sex. Dr Naveen Puri describes how to recognise the signs of syphilis, and what you should do if you think you may have it.
Did our Sexually transmitted infections (STIs) information help you?
We’d love to hear what you think.∧ Our short survey takes just a few minutes to complete and helps us to keep improving our health information.
∧The health information on this page is intended for informational purposes only. We do not endorse any commercial products, or include Bupa's fees for treatments and/or services. For more information about prices visit: www.bupa.co.uk/health/payg
This information was published by Bupa's Health Content Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals and deemed accurate on the date of review. Photos are only for illustrative purposes and do not reflect every presentation of a condition.
Any information about a treatment or procedure is generic, and does not necessarily describe that treatment or procedure as delivered by Bupa or its associated providers.
The information contained on this page and in any third party websites referred to on this page is not intended nor implied to be a substitute for professional medical advice nor is it intended to be for medical diagnosis or treatment. Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites. We do not accept advertising on this page.
- Overview of sexually transmitted infections. BMJ Best Practice. bestpractice.bmj.com, last updated December 2020
- A BASHH Guide to Safer Sex. British Association for Sexual Health and HIV (BASHH). bashh.org, accessed October 2021
- Sexually transmitted infections. PatientPlus. patient.info, last reviewed June 2016
- Chlamydia genital infection. PatientPlus. patient.info, last reviewed August 2016
- Gonorrhoea infection, BMJ Best Practice. bestpractice.bmj.com, last reviewed September 2021
- Anogenital Warts. PatientPlus. patient.info, last reviewed June 2015
- Syphilis infection. BMJ Best Practice. bestpractice.bmj.com, last reviewed September 2021
- Genital Herpes Simplex. Patient. patient.info, last reviewed October 2015
- Oxford Handbook of General Practice. Oxford Medicine Online. oxfordmedicine.com, published June 2020
- Sexually transmitted infections. Patient. patient.info, last reviewed June 2016
- A healthy sex life. Terrence Higgins Trust. tht.org.uk, last reviewed January 2019
- Sexual health. National Institute for Health and Care Excellence. nice.org.uk, published February 2019
- Refer Yourself to NHS Sexual Health Services. Patient. patient.info, last reviewed March 2019
- Genitourinary History and Examination (Female). Patient. patient.info, last reviewed June 2019
- Sexually Transmitted Infections in Primary Care 2013. Royal College of General Practitioners/British Association for Sexual Health and HIV. bashh.org, accessed October 2020
- Changes to the National Chlamydia Screening Programme. Public Health England. gov.uk, published June 2021
- UK National Guidelines on safer sex advice. The Clinical Effectiveness Group of the British Association for Sexual Health and HIV (BASHH) and the British HIV Association (BHIVA). bashhguidelines.org, published July 2012
- PreP. Terrence Higgins Trust. tht.org.uk, last reviewed October 2020
- Health Matters: Preventing STIs. UK Health Security Agency. ukhsa.blog.gov.uk, published August 2019
- Genital tract chlamydia infection. BMJ Best Practice. bestpractice.bmj.com, last reviewed September 2021
- Chlamydia – uncomplicated genital. NICE Clinical Knowledge Summary. cks.nice.org.uk, last updated March 2021
- LGV (lymphogranuloma venereum). Terrence Higgins Trust. tht.org.uk, last reviewed September 2018
- Genital warts. BMJ Best Practice. bestpractice.bmj.com, last reviewed September 2021
- Scenario: Childhood immunization – over 10 years of age. NICE Clinical Knowledge Summary. cks.nice.org.uk, last updated July 2021
- Gardasil. Electronic Medicines Compendium. medicines.org.uk, last updated April 2021
- Information on HPV vaccination. Public Health England. gov.uk, published September 2021
- Gardasil 9. Electronic Medicines Compendium. medicines.org.uk, last updated June 2021
- Human Papilloma Virus Infection. MSD Manuals. msdmanuals.com, last reviewed December 2020
- Herpes simplex virus infection. BMJ Best Practice. bestpractice.bmj.com, last reviewed September 2021
- Gonorrhoea. Patient. patient.info, last reviewed June 2021
- Gonorrhoea. NICE Clinical Knowledge Summary. cks.nice.org.uk, last reviewed November 2020
- Hepatitis B. BMJ Best Practice. bestpractice.bmj.com, last reviewed September 2021
- Hepatitis C. BMJ Best Practice. bestpractice.bmj.com, last reviewed September 2021
- Hepatitis B. Patient. patient.info, last reviewed July 2016
- Hepatitis C. Patient. patient.info, last reviewed December 2018
- Hepatitis A. Terrence Higgins Trust. tht.org.uk, last reviewed September 2018
- Hepatitis B Vaccination and Prevention. Patient. patient.info, last reviewed June 2015
- Human Immunodeficiency Virus. Patient. patient.info, last reviewed September 2020
- HIV Post Exposure Prophylaxis. Patient. patient.info, last reviewed April 2015
- Pubic and body lice. Patient. patient.info, last reviewed January 2017
- Syphilis. NICE Clinical Knowledge Summary. cks.nice.org.uk, last updated December 2019
- Syphilis. Patient. patient.info, last reviewed December 2016
- Syphilis infection. BMJ Best Practice. bestpractice.bmj.com, last updated 29 July 2021
- How to use self-test kits safely. NHS. www.nhs.uk, last reviewed 28 February 2019
