Common STIs and their symptoms

Dr Nicholas Antonakopoulos

Medically reviewed by

Dr Nicholas Antonakopoulos

Last reviewed: 17 Mar 2019

Types of STIs, their symptoms, and how they compare

Man outside building typing on mobile phone to see a list of STDs

Key takeaways

  • The most common STIs in the UK are chlamydia, genital warts, genital herpes, and gonorrhea

  • Other serious STIs include hepatitis B&C, syphilis and HIV. There are also non-STI infections with similar symptoms

  • If you are worried you may have caught an STI you can get home test kits and treatment from ZAVA

  • Many STIs do not have symptoms, so you cannot know for sure that you do not have an STI without testing

The following list of STIs will provide you with information on the different types of sexually transmitted infections as well as the main symptoms for each of them. STIs (or STDs) are infections that can only (or mostly) be passed on to another person when having sex, be it anal, oral or vaginal sex. There are different types of STIs, from very benign to potentially very harmful ones.

If you worry you may have been infected, our sexual health clinic offers home STI test kits for different kinds of infections as well as STI treatments (for chlamydia, genital herpes and genital warts) – delivered to your door by our partner pharmacy.

List of STIs and their symptoms

The most common types of STIs in the UK include chlamydia, genital warts, genital herpes, gonorrhoea, (among the treatable ones), but also hepatitis B&C, syphilis and HIV(among the incurable and/or very severe ones).

Then there are also various other STIs of the urinary tract and the genitals which can cause annoying symptoms but are usually easy to cure. The sooner your infection is diagnosed, the better your chances of getting it treated and cured.


Chlamydia is the most common STI in the UK. It is also easily curable - chlamydia treatment usually consists of a course of antibiotics. About 50% of men and 70% of women do not have any symptoms for years (if at all).

When symptoms of chlamydia appear, people often suffer from abnormal vaginal discharge and vaginal bleeding, discharge from the tip of the penis and pain when peeing or during sex.

When left untreated, chlamydia can lead to infertility in women and men. When you’re infected with chlamydia, other STIs may also be present.


Gonorrhoea is often caught alongside chlamydia. About 1 in 3 women infected with gonorrhoea also has chlamydia. The bacteria that cause gonorrhoea need to be inside the human body to survive. For this reason, you can only catch it through sexual activity (and not through contact with objects/swimming etc).

The symptoms of gonorrhoea include the same irregular discharge as the one caused by chlamydia (from the vagina or penis). As with chlamydia, many infected patients won’t develop any symptoms even though the infection can cause damage to women’s reproductive system in the long run.

Men, however, sometimes suffer from infections of the urinary tract and associated symptoms when infected with gonorrhoea: painful urination and discharge from the penis. If untreated, the bacteria can spread to the rest of the body, sometimes infecting the skin or muscle joints.

Gonorrhea treatment normally involves a course of antibiotics.

Genital herpes

Over 80% of people who are infected with genital herpes, don’t know they have the virus. Most of them will never find out - it’s quite common for patients to live a lifetime without knowing about their infection or suffering from any symptoms.

However, they can pass the virus to another partner who can then develop symptoms. Asymptomatic patients tend not to use protection (condoms) every time they have sex, unlike patients who know they have herpes.

Genital herpes is caused by the herpes simplex virus. The symptoms are soreness of the infected area and/or painful blisters around the genitals. Most people are able to recognise recurrent episodes due to the itching and tingling sensation in the genitals that they feel a few hours before the blisters appear. This is the best time to start an antiviral treatment, right before the virus starts producing genital herpes blisters.

In general, the first herpes outbreak is the most severe one and lasts longer than any episode that follows – up to 2-3 weeks. Over time, outbreaks of genital herpes tend to get milder.

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Genital warts

Genital warts (also known as anogenital warts) are located in or around the anus and genital area. They’re caused by the human papilloma virus (HPV) which often doesn’t cause any symptoms at all, and sometimes shows only years after infection.

Genital warts appear as little bumps that sometimes form clusters with a cauliflower shape. Since they come in different sizes treatment ranges from creams (e.g. Warticon) to surgery (e.g. laser, cryosurgery).

While they are not dangerous, they are easily transmitted and require treatment. As far as symptoms go, genital warts are sometimes itchy and in rare cases they can be painful. Women can suffer from irregular vaginal bleeding or discharge.


Syphilis is one of the oldest infections on this list of STIs. While, nowadays, syphilis is fairly easy to treat with antibiotics, if left untreated the infection can cause severe symptoms (e.g. contagious ulcers on the genitals, anus and mouth; then infection of the brain, eyes or ears) and is potentially life-threatening.

In the early stages, like many types of STIs, the symptoms of syphilis are hard to recognise and it can take several months before they appear. However, as soon as the bacteria enters your body, the illness progresses – in three stages – with the symptoms getting worse at each stage.

Hepatitis B

As for hepatitis B, it is a virus that attacks the liver (like hepatitis C) and is passed through sexual contact and blood (e.g. via needles). The symptoms of hepatitis B start with a short acute infection to which everyone responds differently: a few will develop chronic hepatitis B and others will develop liver dysfunction.

The majority of people actually develop their own antibodies against the virus and are protected from further infections. Yet, 5 in 100 people who are infected will suffer from serious consequences from the virus.

Note that hepatitis A and C can also be passed on through sexual activity but it remains quite rare, so we won’t include them in this list of STDs. If you have had unprotected sex you may need to get tested for hepatitis as well as other STIs.

HIV – Human Immunodeficiency Virus

Finally, HIV is the last item on this list of the different STIs. It’s caused by a virus that attacks your immune system. The HIV virus doesn’t kill you directly, but if you have the virus, any benign infection that your body cannot cope with may cause death. This is the final stage where HIV infection leads to AIDS – Acquired Immune Deficiency Syndrome (i.e. your immune system is down).

Like Hepatitis B, HIV can be transmitted through blood exchange (for example sharing needles) or sex. It can also be transmitted by a pregnant woman to her baby. And like Hepatitis B and other types of STIs, the first symptoms are difficult to recognise as they can feel like the flu (with muscle pain, sore throat), sometimes in combination with vomiting and diarrhoea.

This fever tends to develop within 2 to 4 weeks after the virus has entered the body, but it can sometimes take several months.

There’s no cure or vaccine for HIV at the moment, but early treatment considerably slows down the spread of the virus in infected patients. There are over 8,000 HIV-positive people in the UK, and an estimated 30% of them are not aware of their condition.

Other infections

There are many infections that are often misunderstood as STIs, such as urethritis, which is simply an infection of the urethra (part of the urinary tract).


Pubic lice (crabs) is another example, which is neither an infection nor a disease but just tiny bugs (lice) that settle in your pubic hair to lay their eggs and reproduce. They are transmitted during intimate contact between the pubic areas of two people.

Many people don’t have any symptoms, but some do suffer from itchy genitals and inflammation. You can only get rid of them with special treatment for lice (shampoos, lotions & creams).

Trichomoniasis (Trich)

Trichomonas is a germ causing a benign infection known as trichomoniasis. It’s a treatable infection which is cured with a simple course of antibiotics. The symptoms it causes are common STI symptoms, namely an abnormal discharge from the genitals and pain when urinating or when having sex.

Not strictly STIs…

There is also a whole range of infections that are sometimes considered to be STIs, but they are not strictly speaking STIs. Although they are sometimes transmitted during sex they may be genital infections that are aggravated by sexual activity.

These STI infections are easily curable and include:

  • Bacterial vaginosis (smelly discharge) in women;
  • Water warts caused by a virus which leads to liquid-filled warts around the genitals. These warts are relatively contagious and can be transmitted by skin contact and exchanging towels and clothes;
  • Chancroid, caused by a bacteria and results in bump-like warts that turn into painful ulcers. The symptoms are very similar to genital warts.

Did you know, ladybirds can also get STIs? But don't worry they cannot pass them on to humans.

Medically reviewed by:
Dr Nicholas Antonakopoulos Accreditations: MBBS, BSc

Dr Nicholas Antonakopoulos graduated from the University of London in 2006. He did his postgraduate training in hospitals in the London area, and he trained for four years in Trauma and Orthopaedic Surgery before completing his training in General practice in 2015.

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Last reviewed: 17 Mar 2019

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