Many STIs that are commonly present within the UK can often be rather easy to miss due to the fact that they can remain completely symptomless for long periods of time. However, just because there are no noticeable symptoms, it doesn’t mean that you are not affected. This point is especially important and we will get back to it – not the least because even when the symptoms are completely absent, the condition can still be transmitted via unprotected sex.

It goes without saying that having multiple sex partners will significantly increase the risk of contracting an STD, but at the same time, any unprotected sex carries a potential risk. And if you do contract a sexually transmitted disease, you will not be immune to it, no matter what your general sexual habits are.

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How can I know if I have an STI?

In this article, we will try to provide you with a most general overview of the most general symptoms of various STIs which are, according to the NHS, rather common in the UK. Naturally, like any other text on the topic, this article also cannot replace professional STI testing which can be conducted both at home with a STI testing kit and in a STI clinic.


Undoubtedly the most common STD in the UK, chlamydia affects more than 200.000 people every year. Caused by a strain of bacteria called chlamydia trachomatis that can be transmitted via unprotected anal, vaginal or oral sex, or the use of shared sex toys.

If infected, both men and women will experience abdominal pain, especially in the lower part of the abdomen. For women, this will be accompanied by bleeding between periods and more intense menstrual bleeding, while men might experience pain in testicles. In rare cases, chlamydia can also spread to the eyes, causing symptoms identical to those of conjunctivitis, including redness, ocular discharge and pain.

However, what makes chlamydia especially difficult to detect is the fact that it can remain completely asymptomatic in up to 80% of women and 50% of men affected. This is why STD testing is crucial and its importance is further emphasized by the fact that even when asymptomatic, when left untreated, this condition can cause severe fertility problems and a number of other complications.


Another bacterial STI, gonorrhoea is caused by a strain of bacteria called Neisseria gonorrhoeae. It can be transmitted by any form of unprotected sex and, similarly to chlamydia, it can remain symptomless for long periods of time, potentially indefinitely. Although it was considered to be relatively rare in the first years of the 21st centuries, recent years brought a noticeable increase in prevalence of gonorrhoea with the most prominent spike being in the year 2013, when the number of affected doubled, reaching staggering 20.000 people within the UK alone.

When symptoms do appear, they are rather unpleasant, yet easily identified. Both sexes can notice an unpleasantly smelling yellow to green discharge from their sex organs, with the possibility of further spread of infection to rectum, eyes or throat where it can cause not only discharge, but also swelling and significant discomfort.

There are also certain symptoms of gonorrhoea that will remain gender-specific. These include:



Swelling of the foreskin of the penis, painful urination, discomfort, tenderness and over-sensitivity of the testicles

Painful and burning sensation when urinating, tenderness and over-sensitivity of the lower abdomen, bleeding between periods, more intensive and painful periods

Despite this array of rather uncomfortable symptoms, this condition can still remain asymptomatic for a significant portion of those affected – 10% of men and 50% of women. Similarly to chlamydia, when left untreated, gonorrhoea can cause infertility and other health problems.


Caused by bacterium Treponema pallidum, syphilis is yet another bacterial STD that is more common in men than in women, with 80% of recorded cases involving homosexual men. This illness is exceptionally dangerous and it evolves through three distinct phases, with each succession being more destructive to the body as a whole as compared to previous phases.

Usually, the first symptom of syphilis that is often overlooked is the formation of a small sore or ulcer called chancre at the site where the transmission took place – usually, penis, vagina, anus, mouth, lips or buttocks. In this phase, swelling of the lymph glands can also occur.

What’s especially troubling with syphilis is the fact that the first and most prominent symptom – often overlooked sore – usually heals by itself within a few week. When this happens, even those who noticed it can simply assume that whatever was the problem, it is now sorted out. But, this cannot be further from the truth. Once the sore has healed, second phase of syphilis usually begins.

At this point, the list of symptoms significantly expands to include:

  • Skin rash on hands and feet
  • Small skin growths on anus or vagina
  • Weight loss
  • Hair loss
  • Symptoms of flu and general malaise
  • Further swelling of the lymph glands

These symptoms aren’t always present – instead they can go through several phases of withdrawal and flare-up. However, if left untreated, these symptoms will go away by themselves in a couple of months. At that point, many may assume that the immune system managed to defeat the infection. And again, this can’t be further from the truth.

The third and final stage of syphilis infection is also called the latent phase, as no symptoms of the infection will continue to be present. However, at this point, the relatively simple treatment with antibiotics will no longer be possible and the chances for potentially life-threatening complications will rise significantly.

The latent phase is followed by delayed tertiary phase which occurs 15 years after the infection on average and includes symptoms such as the formation of so-called gummas, soft, tumour-like inflamed balls on the skin, bone and liver. In addition, the disease can spread to other organs, causing blindness, permanent neurological damage and even death.

Genital herpes (HSV-2)

As opposed to conditions discussed so far, genital herpes is a viral STI caused by herpes simplex virus (often abbreviated to HSV). Its easily recognizable and very uncomfortable symptoms include the formation of painful blisters in the genital region. It is a very contagious condition, transmitted through direct contact between mucous membranes. Despite this, symptoms of herpes can often be absent, or can go through various periods of remission and flare-up.

It is important to note that HSV is not just one specific type of a virus – instead, this term denotes various closely related strains that can, in turn, infect different mucous membranes in the body. For example, HSV-1, also known as cold sore is not an STD and anyone can get affected. This type of HSV virus usually infects the area around the mouth. On the other hand, HSV-2 is a type of virus commonly known as genital herpes and as such, it affects the genital area.

Aside from the tell-tale blisters, symptoms include painful urination, general malaise and vaginal discharge and blisters on the cervix in women.

It is important to note that once when this virus enters the body, it cannot get completely cured. However, with proper treatment, it can be successfully managed, so that flare-ups of symptoms remain rare if not completely absent.

Genital warts

Genital warts are a very common viral STI, ranked as the second most prevalent in the UK. Caused by Human papillomavirus, better known as HPV, is moderately contagious as it is transmitted through skin-to-skin contact. The symptoms of genital warts are relatively easy to recognize, with the tell-tale sign being the formation of clusters of small growths in the genital area. The growths will have an appearance of cauliflower.

In affected women, the growths usually appear inside the vagina, on the vulva, cervix, upper thighs or anus, while for men, the most common locations include penis, anus, urethra, scrotum, upper thighs. However, these symptoms do not necessarily occur as soon as one contracts the virus – on the contrary, genital warps can lay dormant for several weeks or even months before the symptoms manifest.

Trichomoniasis (TV)

Unlike any of the STIs considered so far, trichomonisasis, also known as TV is a sexually transmitted disease caused by a parasitic infection. According to the most recent estimates, it affects roughly 6000 residents of the UK annually, with around 50% of them not experiencing any symptoms.

Once symptoms do manifest, they tend to be rather gender-specific:

  • Irregular vaginal discharge (changes in consistency, colour or smell)
  • Pain and inflammation around the vagina
  • Itching in the upper thighs
  • Painful urination
  • Painful sexual intercourse

Males experience the following symptoms:

  • Infection of the urethra
  • Infection of the foreskin
  • Inflammation of the prostate gland
  • Painful urination
  • Painful ejaculation
  • Frequent urination
  • Thin white discharge and soreness around the head of the penis (balanitis)

Bacterial vaginosis (BV)

Bacterial vaginosis, usually abbreviated to BV is yet another very specific health condition. While it is commonly called a sexually transmitted infection, this is not completely true. This condition does affect the vagina, but it is not transmitted through unprotected sex. In fact, while sexually active women are at a higher risk, any woman can get affected. The tell-tale sign of BV includes thin and grey vaginal discharge of unpleasant “fishy” smell. However, many affected women don’t experience any symptoms whatsoever.

On the other hand, this condition is very easily treated with oral antibiotics and while it can cause some complications, those cases are very rare.


As can be deduced from the text above, many of the common STIs in the UK can remain asymptomatic for long periods of time. This means that virus, bacteria or parasite that is the main cause of the condition can be present in the body without displaying any noticeable symptoms. This is why STD testing is of uttermost importance for your health if you are practicing unprotected sex.