What are STIs and when should you get tested?

Find out how and when to get an STI test.

Every year, around 400,000 people in England pick up an STI [1]. Left untreated, STIs can cause all sorts of complications, including cancer, infertility, and problems with pregnancy, which is why practising safe sex and having access to appropriate STI testing are both important. 

But how do you know when you need an STI test? We look at how STIs are spread, where you can get checked, and how to protect yourself from STIs. 

How are STIs spread?

STIs, or sexually transmitted infections, are mainly spread via sexual contact, which can include vaginal, anal, and oral sex. Yet, it is possible to get an STI without having sex.  

The bacteria, viruses, and parasites that cause STIs can be spread through kissing, genital skin-to-skin contact, sharing sex toys, sharing needles, or from a mother to their child.  

Five ways STIs are spread without having sex: 

  • Kissing — although considered low risk, kissing can transmit cytomegalovirus (CMV), herpes, and syphilis, especially when sores are present.  
  • Genital skin-to-skin contact — genital contact can spread genital warts and herpes.  
  • Sharing sex toys — sex toys can pass on STIs and blood-borne infections. You can reduce this by keeping them clean and covering penetrative sex toys with a condom. 
  • Mother to child — STIs may be transmitted during pregnancy, childbirth, and breastfeeding. 
  • Needle sharing — viruses, like HIV and hepatitis, can be passed on through blood-to-blood contact.  

     What is the green Mediterranean diet?

Who’s most at risk of an STI? 

Anyone sexually active is at risk of an STI, but certain groups are at greater risk, including:  

  • Young people aged 15–24 years old 
  • People who have unprotected sex with multiple partners 
  • People with a history of STIs 
  • Men who have sex with men (MSM) 
  • Black minority ethnic populations 

What are the symptoms of an STI?

Symptoms of STIs range from changes to your genitals (like sores, bumps, or skin growths) to pain during sex. They can develop within a few days or weeks and sometimes don’t appear until months or even years after you’ve contracted an STI.  

Your symptoms will depend on the type of STI that has been contracted – and remember, some STIs do not show any symptoms at all. 

Symptoms of STIs: 

  • Sores, bumps, or skin growths on the genitals or anus 
  • Pain or a burning sensation when urinating 
  • Unusual discharge from the vagina, penis, or anus 
  • Pain during sex 
  • A genital rash 
  • Itchy genitals or anus 
  • Unusual vaginal bleeding 

I don’t have symptoms – should I test?

If you do not have any symptoms of an STI, but are sexually active and have multiple partners or unprotected sex, then regular testing is the best way to find out whether you have contracted an STI. How often you should get tested depends on how often you’re having sex. Here’s a rough guide:  

If you do not have symptoms but are sexually active, you should get an STI test: 

  • At least every three months if you have lots of sexual partners. 
  • At least every six months if you don’t have a regular partner and you have casual sex. 
  • At the start of a new relationship, especially if you’re thinking about not using condoms. 

I’m experiencing symptoms – should I test?

People with symptoms should attend their local sexual health clinic as soon as possible. Do not delay getting treatment as you’ll be at a higher risk of complications and spreading the infection to others. 


How and when to get an STI test

If you have symptoms of an STI, you need to visit your local sexual health clinic as soon as possible and they will offer testing straight away. In the meantime, abstain from sex or practise safe sex using protection — this includes oral sex. Depending on your sexual practices, you may need to provide swabs for testing, which you’ll need to do at a sexual health clinic.  

If you suspect you have been exposed to HIV, you should attend an STI clinic or your nearest A&E urgently. You may be eligible for post-exposure prophylaxis (PEP) within 72 hours of the suspected exposure.  

Some STIs don’t show up immediately after sex. Therefore, if you have already taken a test, you should repeat it after the given timeframe to ensure the result is accurate. 

A Medichecks or online sexual health test is most suitable for asymptomatic people who are looking for peace of mind. If you have symptoms, then an online STI test isn’t suitable, and you shouldn’t delay getting tested or treatment.  

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Results are most accurate: 

  • Two weeks after a sexual encounter for chlamydia and gonorrhoea 
  • Four weeks after a sexual encounter for HIV and syphilis (often with a repeat test at three months) 

Ways to get a sexual health check-up:  

  • Attend a sexual health clinic – if you have symptoms of an STI, you must attend a clinic. Book an appointment with your nearest sexual health clinic.  
  • Order a test to your home – If you don’t have symptoms of an STI, but are looking for peace of mind, our 6-in-1 STI Blood and Urine Test checks for six of the most common STIs, including gonorrhoea, chlamydia, and HIV. You may also require further tests, such as rectal, throat or vaginal swabs, depending on the type of sex you have. Men who have sex with men (MSM) are advised to carry out triple-site testing (throat, rectal, and urine tests). 
  • Find a free online service – depending on where you live, there are also some free online sexual health services available.  

If you need sexual health advice, you can also call the National Sexual Health Helpline free on 0300 123 7123.  

How long do STI test results take? 

STI results are usually available in seven to ten days. Our 6-in-1 STI Blood and Urine Test aims to return results within five working days. If there’s a high chance you have an infection, you may be given treatment before the results come back. Although we do not provide treatment for STIs, we can signpost you to appropriate treatment services. 

Can STIs be cured?

The good news is that most STIs are treatable, and even those without a cure can be effectively managed. 

More than 30 different microorganisms can be spread via sexual contact [3], which may be caused by bacteria, viruses, and parasites. Generally, bacterial STIs can be treated with antibiotics and parasitic STIs can be treated with creams or antibiotics. Viral STIs often have no cure, but some treatments can improve symptoms and prevent the infection from spreading.  

  • Bacteria — chlamydia, gonorrhoea, and syphilis 
  • Viruses — HIV, hepatitis B, and human papillomavirus (HPV/genital warts) 
  • Parasites — pubic lice, scabies, and trichomoniasis 

HIV – tests and treatments

HIV can be transmitted in several ways, through sharing blood and other bodily fluids. HIV can sometimes take years to show itself and people frequently have no early symptoms at all or mistake them for flu-like symptoms. Regular testing is important to help keep you and others protected, yet there are steps you can take if you believe you may have been exposed to HIV. 

What is post-exposure prophylaxis (PEP)? 

PEP is a medication to reduce the chance of HIV transmission, but it must be taken as soon as possible and within 72 hours of the suspected exposure. PEP is available in sexual health clinics or if it’s out of hours, you can attend A&E.  

If you think you may have been exposed to HIV (had sex with someone with HIV or someone whose HIV status you do not know), you may be suitable for post-exposure prophylaxis (PEP)

What is pre-exposure prophylaxis (PrEP)? 

PrEP (pre-exposure prophylaxis against HIV) is a course of pills that protects you from HIV. It’s most suitable for people who are HIV-negative but at high risk of HIV. PrEP will not protect you from STIs or unplanned pregnancy. You should continue to practise safe sex. Find out if you’re eligible for PrEP.  

How to prevent STIs

Anyone who has sex can get an STI — you don’t need to have lots of sexual partners. The best way to avoid catching an STI is to practise safe sex. 

Lower your risk of catching an STI by:  

  • Using a condom for any sexual activity, including vaginal, anal, and oral sex.
  • Talking to your partner(s) about STIs, sexual health, and contraception before having sex.
  • Getting tested regularly, especially before sexual activity. 
  • Avoiding sex when under the influence of alcohol or drugs.
  • Getting vaccinated against human papillomavirus (HPV) and hepatitis B (if advised by your sexual health practitioner).

     What is the green Mediterranean diet?

Sexual health help and support

Read our 5 surprising facts you didn’t know about STIs or find more information on STIs from the NHS, Terence Higgins Trust, and Let’s Talk About It.  



  1. GOV.UK. 2022. Sexually transmitted infections (STIs): annual data tables. [online] Available at: <https://www.gov.uk/government/statistics/sexually-transmitted-infections-stis-annual-data-tables> [Accessed 29 Dec 2023]. 
  2. GOV.UK. 2022. Health matters: preventing STIs. [online] Available at: <https://www.gov.uk/government/publications/health-matters-preventing-stis/health-matters-preventing-stis> [Accessed 29 Dec 2023]. 
  3. WHO. 2022. Sexually transmitted infections (STIs). [online] Available at: <https://www.who.int/news-room/fact-sheets/detail/sexually-transmitted-infections-(stis)> [Accessed 29 Dec 2023].

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