EESH! The thought of a sexually transmitted infection might make your skin crawl and the hairs on your arms stick up. We’re talking genitals, after all.
But it’s a serious conversation to be had, and symptoms are not something to brush off as just icky. Some are so ‘ordinary’ that you wouldn’t even notice them.
If you suspect you might have an STI, it’s important not to turn a blind eye Credit: Getty
Gonorrhoea cases have increased by more than 300 per cent in just a decade Credit: Getty
But it’s important you do, as STIs gone unchecked and untreated can have horrible consequences – not least, infertility.
The latest data by the UK Health Security Agency (UKHSA) reveals that in 2025, there were 334,151 new STI diagnoses.
It’s true that STIs are most common in under 25s, but cases are on the rise among over-55s.
Research in the Journal of Applied Gerontology found that 87 per cent of over 55s reported not using barrier protection such as condoms during their last sexual encounter, increasing their risk of STIs.
Despite what their name suggests, STIs aren’t always passed on through penetrative sex.
Dr Babak Ashrafi, GP at Superdrug Online Doctor, says that depending on the infection, they can be transmitted through vaginal, anal or oral sex, skin-to-skin genital contact and sharing sex toys.
He adds: “Some infections can also be passed through non-sexual routes such as infected blood or close bodily contact.
“Many infections can be completely symptomless, which is why testing is so important if you think you may have been exposed,” he says.
Knowing what to look out for can help you to get tested and treated quickly.
Here are some symptoms you may not have realised are related to an infection.
1. UTI-type burn
Chlamydia is the most common STI in the UK, with more than 150,000 cases annually Credit: Getty Images
Chlamydia is an easy STI to miss as it’s so often symptomless – regardless, it is the most commonly diagnosed STI, with more than 150,000 cases last year.
When there are symptoms, they can vary hugely.
Dr Ashrafi says: “Better known signs include unusual vaginal or penile discharge, pain or burning when urinating, bleeding between periods or after sex, and pain or swelling in the testicles.
“Some of the more subtle signs can include lower abdominal or pelvic pain. Chlamydia can also affect the rectum or throat depending on the type of sexual contact.”
If it’s in your rectum, you may feel itchy and notice discharge or bleeding.
“If symptoms do develop, they may not appear until several weeks after infection, so feeling completely well after a potential exposure doesn’t necessarily mean you don’t have chlamydia,” adds Dr Ashrafi.
You can usually order a free chlamydia test online, a urine or swab test.
A course of antibiotics will likely be prescribed if you’re found to have chlamydia.
Sex and your body
Everything you need to know about sex and your body:
2. Ulcers
Although it’s less common than other STIs, left untreated, syphilis can lead to severely debilitating symptoms.
There are around 8,200 cases per year.
Dr Stevenson says: “Stage one syphilis usually causes an ulcer.
“This may be painful or painless and develops where the infection enters the body.
“Less commonly, it can cause skin changes that look like psoriasis, eczema or skin ulcers.”
As well as this, as symptoms develop, syphilis can also cause isolated swelling of the head of the penis, enlarged or swollen lymph nodes and/or raised lesions at the corners of your mouth.
Dr Strevenson adds: “You may notice patchy hair loss, weakness and vision changes too.
“In rare cases where the condition has progressed to tertiary syphilis, it can cause neurological changes such as seizures, tinnitus, persistent headaches and vertigo.”
Visit your nearest sexual health or GP surgery for testing.
A single antibiotic injection or a course of injections is the usual treatment for early syphilis.
3. Diarrhoea
If you’ve got diarrhoea, you’re probably aware you’ve picked something up. But don’t always assume it’s food poisoning.
Shigella is a tummy bug that, while typically spread via food and contaminated surfaces touched by an infected person, can also be sexually transmitted.
This is particularly the case among gay, bisexual, and other men who have sex with men (MSM).
Cases have soared by 25 per cent in England in just two years, with numbers rising from 2,052 in 2023 to 2,560 in 2025, latest UKHSA stats show.
“One of the most important things to understand about Shigella is that the infectious dose is very low, meaning that ingesting just a tiny amount of contaminated material can be enough to cause illness,” the UKHSA says.
“This makes it relatively easy to transmit from person to person.”
4. Lower back pain
A sharp or dull pain affecting the lower back could be a sign of herpes, experts say Credit: Getty
Herpes, which increased in case numbers to more than 28,700 last year, is mostly known for its small blisters around the genitals or anus, “which burst and leave painful sores,” says Dr Ashrafi.
“People may also experience itching, tingling or burning around the area, as well as pain when urinating.”
It’s easy to mistake herpes for spots or ingrown hairs, as the two can look similar.
Dr James Stevenson, associate clinical director at Bupa Health Clinics, says herpes can also look like small, shallow cracks or splits in the skin.
He adds: “You might experience a sharp or dull pain affecting your lower back, thighs or buttocks.
“This can happen even if you do not have any visible blisters, bumps or sores around your genitals.
“Because herpes can affect the genital area, including the nearby nerves, inflammation in this area can cause temporary difficulty and soreness passing urine.”
Herpes symptoms can also be flu-like, such as a fever or swollen glands.
Herpes is caused by two types of the virus, known as HSV-1 and HSV-2, which can lie dormant in your body for life.
This means that, though it is there lifelong, symptoms can come and go.
Dr Stevenson says: “Many people may be affected by genital herpes once and never have another outbreak. Or, it might be several years between outbreaks.”
You may be eligible for a free at-home herpes testing kit, or visit your nearest sexual health centre.
Dr Ashrafi says: “Symptoms can settle on their own or be treated with antiviral medicines.
“It’s important to start any prescribed treatment as soon as possible if you think you may have genital herpes.”
5. Damp feeling
One of the most hardest STIs to spot is genital warts.
“They typically appear as small fleshy growths or bumps around the genitals or anus,” says Dr Ashrafi.
“They can appear individually or in clusters but they aren’t necessarily large or immediately obvious.
“Instead, they can be very small or flat and therefore difficult to notice.”
The warts won’t usually cause you any pain but you might feel itchy.
Occasionally, you may notice vaginal bleeding during sex.
Or, you may feel damp in the area of your warts.
Genital warts are caused by the human papillomavirus (HPV), which can be passed through sex but also skin-to-skin contact.
It’s one of the rarer STIs, causing 23,280 cases in 2025.
Dr Ashrafi says: “Warts can develop weeks or months after becoming infected with HPV, and sometimes even later, which means their appearance doesn’t necessarily tell you when you acquired the infection.”
If you notice an unfamiliar lump or growth around your genitals, have it properly assessed.
Typically, you will be prescribed a cream or lotion to get rid of the warts.
Gonorrhoea complications
If gonorrhoea isn’t treated, it can cause serious problems including:
Eye infections (gonococcal conjunctivitis) if you touch your eyes after touching infected fluid from your penis or vagina
An infection of the womb, fallopian tubes and ovaries (pelvic inflammatory disease), which can lead to infertility if not treated
Infection in the testicles or prostate (prostatitis)
The sooner you get treatment, the easier these complications are to treat.
Having gonorrhoea during pregnancy can increase your risk of premature birth and your baby having a low birth weight.
There’s also a risk the infection could spread to your baby’s eyes during birth, which is called gonococcal conjunctivitis.
This can cause blindness if it’s not treated with antibiotics.
Source: NHS
6. Pelvic pain
Could you name a symptom of gonorrhoea?
Some 63,900 cases were spotted last year, making it one of the more prevalent STIs.
“Symptoms of gonorrhoea include an unusual vaginal or penile discharge,” says Dr Ashrafi.
If you notice your discharge looks different to normal, it’s worth noting.
“[It might be] yellow or green, alongside pain or burning when urinating,” says Dr Ashrafi.
Dr Ashrafi says: “Women may experience bleeding between periods, while men can develop pain or swelling in the testicles. Pelvic or lower abdominal pain can also occur.”
Left untreated, gonorrhoea can cause serious problems, potentially leading to infertility and infection in the testicles or prostate. So do not delay getting tested and treated.
Gonorrhoea in the rectum can cause itching, discomfort, discharge or bleeding.
Dr Ashrafi says: “Symptoms often appear within around two weeks of infection, although they can take longer.”
To find a testing centre near you, visit the NHS ‘Find a Sexual Health Centre’.
A course of antibiotics is the usual treatment for gonorrhoea.
According to the NHS, touching your eyes after touching infected fluid from your penis or vagina, can lead to an eye infection called gonococcal conjunctivitis.
7. Itchy skin
There are dozens of causes of itchy skin, from eczema to a new laundry detergent.
But if it comes with diarrhoea and dark yellow wee, these are potential signs of hepatitis.
This is an inflammation of the liver tissue.
Hepatitis A can be spread by sex, close contact with someone who has the infection or sexual activity that involves contact with faecal matter.
Hepatitis B can be transmitted through infected blood and certain bodily fluids, including during sex.
These are just some of the ways hepatitis, which has many types, can spread, though.
Dr Ashrafi says that subtle signs of hepatitis can be confused for another illness, including fever, diarrhoea, joint or muscle pain and itchy skin.
He says: “Some of the better known signs include fatigue, nausea or vomiting, loss of appetite, abdominal discomfort, dark urine, pale stools and jaundice, where the skin or whites of the eyes turn yellow.”
Symptoms can typically develop around two to seven weeks after infection.
A blood test will test for hepatitis. This can be done at your GP surgery or at a sexual health clinic. You may be prescribed medications to control symptoms.
8. Headaches
Possible early signs of HIV include swollen glands, headaches and muscle or joint pain Credit: Getty
When it comes to HIV, symptoms are very similar to other common illnesses, making it hard to spot. But if HIV isn’t treated, it can develop into AIDS which is fatal.
While cases of HIV among men who have sex with men has been steadily decreasing, they have risen among straight men and women in the recent five years.
Overall, there were 6,400 new cases in 2023, according to the National Aids Trust.
Dr Ashrafi says: “Some people develop a short flu-like illness following a HIV infection, which can include a fever, sore throat, rash and fatigue.
“Other possible early signs include swollen glands, headaches and muscle or joint pain. None of these symptoms is specific to HIV, and some people won’t experience noticeable symptoms at this stage at all.”
When early symptoms do occur, they often appear within the first few weeks after infection.
“After this initial period, someone with untreated HIV can have no noticeable symptoms for years, which is why HIV should never be diagnosed or ruled out based on symptoms alone.”
If you have any doubt that you may have contracted HIV, take an at home test or visit a sexual health clinic.
HIV can be treated with anti-HIV medicines called antiretrovirals, which are tablets to be taken every day.
