Do you know the signs of the 8 most common STIs?


If you have unprotected sex, there’s always a chance you could have contracted an STI - even if you have no symptoms.
In fact, 7 out of 8 of these STIs listed can be asymptomatic, meaning you may have no symptoms.
With Sexual Health Week just around the corner, it’s a reminder to prioritise your sexual health more than ever.
In this guide, we have compiled a list of the 8 most common STIs and their symptoms so you can give yourself peace of mind - but remember, don’t count on your symptoms alone to let you know something is wrong!


Chlamydia is the most common STI in the UK for under 25s, and is often known as the ‘silent infection’ due to 75% of women and 50% of men reporting no symptoms. 
If you have contracted chlamydia, it can often take a couple of weeks for symptoms to appear, and they differ between men and women.
The usual symptoms for women include: pain when urinating, unusual vaginal discharge, pain in the stomach or pelvis, pain or bleeding after sex, and bleeding between periods.
If chlamydia is left untreated, it can lead to serious complications such as pelvic inflammatory disease (PID) which is a major cause of ectopic pregnancies and infertility in women.
For men, you may notice pain when urinating; white, cloudy or watery discharge from the tip of the penis; burning or itching in the urethra (the tube which carries urine out of the body) and pain in the testicles.
If you don’t get the infection treated, it can cause swelling in the epididymis (the tubes which carry sperm from the testicles) and affect your fertility.
Chlamydia isn’t just limited to your genitals, either - you can also contract it in your rectum, throat or eyes if you have unprotected anal or oral sex.
In your rectum you may experience symptoms of discomfort or discharge, and in your eyes you may have redness, pain and discharge (conjunctivitis).


Like chlamydia, you could have contracted gonorrhoea (sometimes known as ‘the clap’) without displaying any obvious signs or symptoms - in fact, half of women and 1 in 10 men will be in this category.
The bacteria can enter the body through the entrance of the womb (cervix), the tube that passes urine, the rectum, the throat and eyes. 
Thankfully, you can’t catch gonorrhoea by kissing or hugging as the bacteria won’t survive outside of the body for long. 
You can only catch this STI by having unprotected vaginal, oral or anal sex, or if you have shared vibrators or other sex toys which have not been cleaned or protected with a condom.
Signs of gonorrhoea in women include: thick green or yellow vaginal discharge, painful urination, vaginal bleeding between periods and abdominal or pelvic discomfort.
The infection can be transferred from a pregnant woman to her baby, so it is important to get screened if you are pregnant or think you might be; if untreated, gonorrhoea can cause permanent blindness to a new-born baby.
For men, if you are experiencing painful urination, thick green or yellow discharge from the tip of the penis, pain or inflammation in one or both testicles, you must get checked.
If gonorrhoea has infected other parts of your body you may notice itching from the infected area, discharge from the rectum or eyes, spots of blood on toilet tissue, straining during bowel movements, eye pain and sensitivity to light; a sore throat and swollen lymph nodes in the neck.



Trichomoniasis is caused by a small parasite and is one of the most difficult STIs to diagnose due its symptoms being similar to others.
Around half of men and women do not experience symptoms, but if symptoms do appear, they will usually be within a month of contracting trichomoniasis.
Symptoms for women include vaginal discharge that may be thick, thin, frothy and a yellow or green in colour; you may also produce more than normal or it may have an unpleasant fishy smell.
The area around the vagina may be sore, swollen and itchy - this might also affect the inner thighs.
Pain when passing urine or having sex is also a symptom of this STI.
Men may experience similar symptoms including soreness, swelling and redness around the head of the penis or foreskin; pain during urination or ejaculation; needing to pass urine more often and thin, white discharge from the penis.

Genital warts

Genital warts are caused by a type of human papillomavirus (HPV).
You will be protected against genital warts if you have had the HPV vaccine which is offered to girls and boys aged 12 -13, men up to the age of 45 who have sex with men, some transgender men and women, sex workers and men and women living with HIV.
Many people carry the genital warts virus without symptoms and unknowingly pass on the virus to others.
Once you have the infection, it can range from weeks to months before you develop any symptoms, so it is important to get tested as soon as possible after you have had unprotected sex.
Unlike other STIs, genital warts can be caught via skin-to-skin genital contact, but you can’t catch it from kissing or sharing things such as towels or toilet seats.
We advise you to go to your local sexual health clinic if you have 1 or more painful growths or lumps around your vagina, penis, anus or upper thighs; itching, bleeding, changes to your urine flow  (for example sideways, instead of downward); or a sexual partner who has genital warts, even if you don’t have symptoms.
Genital warts are not the same as warts on the hands or the feet, and over the counter treatments will not be effective - you must seek advice from your GP or sexual health clinic.

Genital herpes

Herpes can affect the genital and anal area, in addition to the mouth and nose, which you may recognise in the form of cold sores. 
Unprotective sex is not the only way you can catch this virus - you can pass genital herpes on by receiving oral sex from somebody who has a cold sore, or if a person with whitlows (herpes on the hand) touches a person’s genital area.
However you can’t get genital herpes from sharing baths, towels, swimming pools, toilet seats, cups, plates or cutlery.
Many people who have genital herpes have no signs or symptoms, although you may experience:

  • Flu-like symptoms, such as a fever, headache, aches and pains
  • Stinging, tingling or itching in the genital or anal area
  • Discharge from the vagina or penis
  • Fluid-filled blisters appearing in the infected area, and when burst, leave behind small red sores which can be very painful - this will cause discomfort when passing urine due to the urine passing over the sores.

Unfortunately there is no cure for genital herpes and recurrences are common, however, they will usually be less severe as your body will have had the opportunity to produce antibodies.
You may find that certain things will trigger an outbreak such as feeling run down, stress, being on your period, friction from sex or masturbation, sunbeds or sunbathing, tight underwear which isn’t cotton, and drinking or smoking excessivley.



Scabies is a common and very contagious disease caused by tiny mites who reproduce on the surface of your skin and burrow into it to lay their eggs.
While scabies is not solely considered an STI, it is usually transmitted through sexual contact.
You can, however, also catch it through prolonged skin-to-skin contact such as sharing a bed with an infected person.
It is unusual to contract this disease through hugging or with a handshake. 
You may have developed scabies if there is a red, itchy, raised rash or pimple-like spots on your skin.
These may look different on darker skin, but you should be able to feel them.
The itching may become worse at night.


You may think syphilis is a disease of the past - with famous sufferers like notorious gangster Al Capone, King Henry VIII and Oscar Wilde.
Whilst it is less common than other STIs, it is slowly on the rise.
The symptoms of syphilis are similar for both men and women and will usually start off mild, leading many to ignore the problem until their condition worsens.
It is sometimes referred to as ‘the great imitator’ due to the symptoms being very similar to other diseases, so it is important to get yourself screened if you have had unprotective sex or are experiencing any of the symtoms featured below.
You cannot transmit syphilis through sharing things such as towels - you can only become infected by having unprotected sex, sharing unclean or uncovered sex toys, or if you are an injecting drug user and share a needle with someone who is infected.
If you are pregnant you could pass syphilis on to your newborn baby, but you and your baby can be treated during pregnancy.
But don’t worry, as all pregnant women are offered a blood test to check if they have syphilis as part of their 11 - 20 week screening.
In the early stages of syphilis, symptoms at this stage may include a small painless sore known as a chancre (pronounced ‘shanker’ which means ‘creepling ulcer’) which will appear on the area where the infection entered the body.
This chancre will not hurt and should disappear after 2 - 6 weeks, but it is extremely infectious.
If syphilis has been left untreated, it can develop into more dangerous stages that can have really serious outcomes like heart disease, dementia, stroke, deafness, blindness and even paralysis. 

Human papillomavirus (HPV)

We covered one of the problems caused by the HPV virus in the genital warts section - but if HPV doesn’t go away on its own, it may increase your risk of developing certain types of cancers in years to come.
You do not need to have penetrative sex to get HPV - it can be transmitted through skin-to-skin contact of the genital area, vaginal, anal or oral sex; or from sharing sex toys.
HPV can have no symptoms, so you may not know you have it - but it is very common and most people will get some type of HPV in their lifetime.
There is no way to determine which people with HPV will develop cancer or other health problems, but those with weakened immune systems may be more at risk.
There is no simple way of finding out if you have HPV, such as a swab or a blood test, which is why many people are not aware they have the virus until they are faced with problems years down the line.
However, HPV tests can be done at cervical cancer screenings, which all women are invited to aged 25 - 64.

As many STIs do not present any symptoms, you could be putting yourself and others at risk if you’ve had unprotected sex.
If you’ve been deliberating getting tested for an STI, we hope this guide has persuaded you to do so.
Don’t be a super spreader! After all, what’s the worst that could happen?
For more information about any of these STIs, visit Brook or the NHS website.


Alexandra Moses - Medical Content Writer
James O'Loan - CEO & Superintendent Pharmacist
James O'Loan , CEO & Superintendent Pharmacist on 15 March 2023
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