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Everything You Need To Know About STIs

But Were Afraid To Ask!

There are over thirty sexually transmitted infections.

This guide gives an overview of their causes, symptoms, testing and treatment.

There are over thirty sexually transmitted infections and this guide gives a summary of the most frequent infections. Learn about their causes, symptoms, testing and treatments. This guide covers:

  1. What Is A Sexually Transmitted Infection?
  2. STDs or STIs? What’s The Difference?
  3. How Are STIs Transmitted?
  4. How Do You Protect Against STIs?
  5. What Are The Most Common STIs?
    1. HIV
    2. Syphilis
    3. Chlamydia
    4. Gonorrhea
    5. Hepatitis B
    6. Genital Herpes
  6. How To Get Tested For STIs?
  7. When to Visit A Doctor About STIs?


What Is A Sexually Transmitted Infection?

Sexually transmitted infections are, as the name suggests, infections that can be transmitted during sex. Some of these infections can also be transmitted by other routes, via contact with blood or other bodily fluids.

Note that STIs are transmissible by any mode of sexual intercourse (vaginal, anal, vaginal or oro-genital (mouth to genital contact).


STDs or STIs? What’s The Difference?

The World Health Organisation (WHO) now recommends the use of the expression "Sexually Transmitted Infection" rather than sexually transmitted disease.

This is because the term “disease” implies the existence of symptoms. However, it is not uncommon to contract an infection without having symptoms. Certainly at the beginning, or even throughout the infection. But the infection is still contagious and can cause ongoing problems.

The use of the term STI is intended to encourage the public to be tested following risk exposures - even without the existence of symptoms. At Vitall we exclusively use the term STI.

But ultimately, STI and STD mean the same thing.


How Are STIs Transmitted (Spread)?

In the case of sexually transmitted infections, the main risk factor is having unprotected sex.

Of course, the more unprotected intercourse you have, and the more multiple partners you have it with, the greater the risk. Likewise, sexual practices like anal sex increase your risk from the blood-borne transmission of STIs like Hepatitis C.

You can assess your risk of infection using our risk assessment tool here.


How Do You Protect Against STIs?

The only real protection to date remains the condom. The male condom is the most common, but the female condom is just as effective. 

The withdrawal technique is not at all effective since STIs are transmissible by many other fluids than sperm.

What Are The Most Common STIs?


HIV is short for Human Immunodeficiency Virus. More specifically, it is a retrovirus.

Retroviruses have the ability to integrate their genome with the DNA of its host cell. These genetic mutations make it a virus against which it is particularly difficult to develop a vaccine.

Gay men are the population most at risk, but the risk of heterosexual transmission is very much present. Anal intercourse with ejaculation is the most at risk, followed by anal intercourse without ejaculation.

HIV destroys the immune system of the infected person. Left untreated it eventually causes acquired immunodeficiency syndrome (AIDS) after about 10 years. 

When AIDS occurs, the immune system has been severely damaged. This results in serious infections and even death that wouldn't be a problem for person with a healthy immune system. 

HIV testing is done by serology (blood test analysis). The screening test can be done in a sexual health clinic or at home using an HIV home test kit. Positive results need further confirmation testing for a full diagnosis.



Since the discovery of HIV in the 1980s research has progressed considerably. Although we cannot completely remove the retrovirus, current therapy has considerably increased the life expectancy of the patients. It is now considered that the life expectancy of an infected and treated person exceeds 70 years. HIV treatment also significantly decreases the contagiousness of patients.

For people who have put themselves at risk from HIV, there's a treatment available called post-exposure prophylaxis (PEP). PEP may prevent HIV infection even after the virus has entered the body.  Anti-HIV medicines are taken for four weeks.

PEP needs to be prescribed immediately after unprotected sex, ideally within 24 hours. It can be prescribed up to 72 hours (three days) after exposure, but it's best not to wait that long. PEP is available for free from NHS sexual health (GUM) clinics and hospital Accident and Emergency departments (A&E).

Note that PEP is not guaranteed to prevent an HIV infection and it isn’t a cure.



Condoms remain the most effective and efficient way of preventing the spread of HIV.

If you’re at risk of HIV in the future, for example you have an HIV positive partner, you might want to consider Pre-Exposure Prophylaxis or PrEP . 

PrEP is a pill that protects you from HIV. It involves taking a course of antiretroviral therapy (tablets) before and after sex. Having antiretrovirals in your body prevents the retrovirus infecting you in the event of contact. 

You can get PrEP here:


Syphilis is a sexually transmitted infection caused by a bacteria called treponema pallidum.

Syphilis is especially common among gay men aged 20 to 59 years.

Syphilis was widespread before the twentieth century. Fortunately, the discovery of antibiotics has considerably reduced this infection over the last century. However, like most STIs, there has been a resurgence of syphilis since the early 2000s.

Syphilis develops in 3 phases, and symptoms usually progress during these phases. There are also cases of latent syphilis, that is, infection without symptoms.

  1. Primary syphilis occurs between 3 weeks and 3 months after infection. The main symptom is the appearance of one or more syphilis sores known as chancres. These are usually painless and disappear within a few weeks.In most cases there is only one chancre. It can be located on the genital areas but it can also appear elsewhere. For example, in the mouth in particular, on the tonsils or the tongue, and also on the anus.
  2. The secondary phase occurs between a month and a year after infection. During the secondary phase, the disease causes numerous skin and mucosal lesions, some of which can be contagious. Symptoms can also include swollen but painless nodes, abnormal fatigue, increased body temperature, and headaches.If syphilis is not identified and treated in this phase, the symptoms will eventually disappear, but the disease will remain dormant.
  3. After a few months or years of inactivity, the disease wakes up to go into the tertiary phase. The effects can then be varied and severe, including damage to your brain, liver, kidneys, heart & digestive organs.

Identification of syphilis is done by serology (blood test analysis) and the resulting antibiotic treatment is very effective. It's included in our essential STI check for men and the corresponding female STI test here.



Chlamydia is a sexually transmitted infection caused by the bacteria Chlamydia trachomatis.

Chlamydia is the most common sexually transmitted infection in the UK and Europe.

Young people represent the population most affected, probably due to having multiple sexual partners and a declining use of condoms.

One of the main features of chlamydia infection is that it very often has no symptoms (i.e. is asymptomatic). In fact, as many as 70% of women and 50% of men experience no symptoms once infected.

People therefore do not know that they are infected and contagious, even though chlamydia home tests are widely available. But left untreated, chlamydia can cause severe health problems, including infertility. This is why regular screening is strongly recommended for sexually active people.

In cases where symptoms appear they are:

In women:

  • Pain in the lower abdomen
  • Unusual and possibly smelly vaginal discharge
  • Burning sensation during urination
  • Vaginal bleeding unrelated to menstruation
  • Abnormal discharge from the anus.

In men:

  • Burning sensation while urinating
  • Swelling and pain in the testicles
  • Itching in the urethra

Screening for chlamydia infection is done by genital swabbing in women and by urine analysis in men.

In the event of a positive infection, treatment is by the administration of antibiotics either as a single dose or over 7 days. The treatment is very effective. Although, in rare cases, the infection can persist, which is why it is recommended to re-screen a few months after treatment.



Gonococcal disease, or gonorrhea is an infection caused by a bacteria called Neisseria gonorrhoeae or Gonococcus.

Most new gonorrhea infections occur in women. It can also be transmitted to newborn babies during childbirth.

Women show no symptoms in 70% of cases. When symptoms do occur, they can include:

  • Yellowish vaginal discharge, sometimes bleeding.
  • Pelvic pain
  • Pain during intercourse
  • Burning sensation during urination and difficulty urinating.

In men the symptoms are more obvious.

  • Discharge of pus from the urethra
  • Burning sensation while urinating
  • Pain and swelling of the testicles
  • Pain and discharge from the rectum

Gonorrhea can also be anorectal in case of anal intercourse. The symptoms are then:

  • Anal itching
  • Discharge from the anus
  • Swelling of the anus
  • Diarrhea
  • Bleeding from the anus
  • Discomfort during defecation
  • Gonorrhea is spread through sexual, oral, vaginal or anal intercourse. The vectors of transmission are biological sera and mucous membranes. Like Chlamydia, Gonorrhea is rarely transmitted by cunnilingus. 

Gonorrhea testing is done by local sampling and you can test for it using this combination chlamydia & gonorrhea home test kit. If detected, gonorrhea is treated with an antibiotic.


Hepatitis B (Hep B)

Hepatitis B is a viral infection that affects the liver. The hepatitis B virus is transmitted by blood and sexual fluids. It is able to survive at least a week outside the human body.

Hepatitis B largely an asymptomatic disease i.e you are unlikely to have symptoms.

After an incubation period of 2 to 6 months the infected individual enters the acute phase of development.  90% of the time no symptoms present. In cases where symptoms do appear, individuals first present with flu-like symptoms followed a few days later by jaundice, the urine becomes dark, and there can be fatigue and itching.

In a large part of the cases, the body gets rid of the virus on its own and the individual is cured. Occasionally (about 1% of cases) the body is too aggressive trying to remove hepatitis. By trying to destroy the virus it also destroys the liver itself. This is known as fulminant hepatitis, when the liver begins to fail very quickly. An emergency liver transplant is the only viable outcome for the patient.

In 10% of cases the cure for Hepatitis B is not complete. The body has fought the virus but has failed to eliminate it completely. The disease then progresses to chronic hepatitis.

In the case of chronic hepatitis, the disease returns regularly. A third of chronic carriers are asymptomatic, the virus is present in their body, but inactive. For the remaining two thirds, the disease can progress to cirrhosis, which can eventually lead to liver cancer.

Hepatitis B screening is done by serology (Hepatitis B blood test analysis). It can be tested together with Hepatitis C in a home test kit, or as part of a high-risk STI screening test.

There are treatments for chronic hepatitis that prevent the virus reproducing. The aim is to slow down the progression of the virus as much as possible.


Genital Herpes

Genital herpes is not caused by a bacterium but by a virus . Once this virus is contracted it is impossible to get rid of it. The infection will be present for life.

It is estimated that 20% of the UK population is a carrier of the genital herpes virus and that 80% of the infected people are unaware that they are infected.

Genital herpes is a chronic disease with symptoms that appear and then eventually go away. It is during these outbreaks that the subject is contagious. But also, there are cases of asymptomatic flare-ups. In these cases, the virus multiplies in the body, but there is no apparent herpes. The subject is just as contagious during sexual intercourse, so it’s when the majority of transmissions occur.

Although there is no treatment to cure the disease, there are oral treatments that can significantly reduce the symptoms of genital herpes. It is recommended to consult a doctor and not to try to treat yourself with over-the-counter medicines. Misuse of treatment can make the disease worse.

How To Get Tested For STIs?

STI screening can be done in several ways:

  1. Sexual health and GUM clinics offer screening services, although these services can be oversubscribed & difficult to make an appointment.
  2. Self-test kits (aka rapid tests) which can be obtained in pharmacies or similar. While convenient, the quality of analysis can be questionable.
  3. STI Home testing services, which Vitall offer, where your sample is sent to a professional medical laboratory for testing. These give both the reassurance of professional analysis with the convenience and privacy of home testing.

There are many infections and asymptomatic cases are not uncommon, which is why regular screening is advised.

When To Visit A Doctor About An STI?

It is recommended to consult a doctor as soon as possible after a risk report. For some STIs there are preventive treatments, their effectiveness depends directly on the time between infection and taking treatment. People with a multiplicity of partners are encouraged to carry out regular screenings.

Get Yourself Tested With Vitall's Home Test Kits

Article Reviewed By

Doctors, Scientists & Experts Delivering Private Blood Testing Online

Ben Starling MSc. |Chief Executive

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