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Sexually Transmitted Infections (STIs)

Sexually Transmitted Infections, popularly called STIs, are primarily transmitted through sexual (e.g. vaginal, anal and oral sex) or initimate contact. These infections can also spread through contact with infected blood and body fluids.

Transmission of STIs to newborns from their mothers having infections is not uncommon, and in most instances can be prevented with adequate medical care of the pregnant mothers.

Most STIs can go without showing any symptoms or signs and that is why it is important to have regular check up for sexually active individuals.

On this page, we will thoroughly cover what you need to know about STIs and information on getting tested & treated.

STI Testing

Accurate from 45 days and with results in 20 minutes, we can help you move on with your life today.

STI Treatments

If you’re at high risk of acquiring HIV, we can look for HIV after 10 days of possible exposure.

HIV-1 viral load test

The HIV-1 Viral Load measures the amount of the HIV virus in your blood – only for HIV positive patients.

List of STIs

The following STIs can affect both men and women and can be present in the body without producing any symptoms. We will cover the symptoms STI may produce below.

Tested from the genital tract

  • Chlamydia (+/- throat/rectum)
  • Gonorrhoea (+/- throat/rectum)
  • Mycoplasma genitalium
  • Trichomonas vaginalis
  • Ureaplasma urealyticum
  • HPV (DNA)
  • Genital herpes (DNA)
  • Haemophilus ducreyi
  • Lymphogranuloma venereum (LGV)

Tested from the blood

  • HIV
  • Syphilis
  • Hepatitis B
  • Hepatitis C
  • Genital herpes (antibody)
  • HTLV 1&2

STIs diagnosed from a clinical examination

  • Genital warts
  • Molluscum contagiosum
  • Genital herpes (not a part of routine STI screens)
  • Pubic Lice
  • Scabies


Other genital infections which are not STIs

  • Bacterial vaginosis
  • Balanitis
  • Candida (Thrush)
  • Cervicitis
  • Gardnerella vaginalis
  • Non-gonococcal urethritis (NGU)
  • Non-specific urethritis (NSU)
  • Pelvic inflammatory disease
  • Urinary tract infection (UTI)


Most STIs are able to be present in your body without you experiencing any symptoms. This is why it is recommended for sexually active individuals to get a regular check up and avoid having any symptoms and complications in the first place (and not to mention prevent passing it onto others).

When symptoms present, they can vary between men and women.

Individual wellbeing

The stress & anxiety caused by having (or even worrying about) an STI is often underestimated (especially by those who don’t specialise in the field). Symptoms of this include difficulty in focusing on studies/work, breakdown of relationships and substantial lifestyle changes.

Genital symptoms in men

  • ‘Doesn’t feel right’ – as often described by patients
  • Discomfort in water pipe
  • Irritation in water pipe
  • Itching sensation
  • Burning sensation
  • Painful urination
  • Pain in testicles
  • Pus-like discharge from urethra
  • “Wetness” at penile tip
  • Redness or inflammation of the foreskin
  • Redness or inflammation of the glans penis
  • Unusual lumps or bumps
  • Ulcers, sores & blisters

Additional genital symptoms in men who have sex with men

  • Irritation in back passage
  • Mucoid or slimy or blood-stained discharge from the back passage
  • Diarrhoea
  • Unusual lumps or bumps in the back passage
  • Ulcers, sores & blisters in the back passage

Genital symptoms in women

  • Abnormal discharge
  • Change in discharge
  • Spotting
  • Bleeding after sexual contact (post-coital bleeding)
  • Bleeding between periods (intermenstrual bleeding)
  • Pain on having sexual intercourse
  • Painful urination
  • Mucoid or slimy or blood-stained discharge from the back passage (with rectal infection)
  • Unusual lumps or bumps
  • Ulcers, sores & blisters
  • Swollen lymph nodes in the groin

Symptoms of STIs can affect areas other than the genital region.

General parts of the body

  • Changes in skin
  • Development of skin lesions


  • Hair loss on scalp
  • Patches
  • Loss of eyebrows
  • Loss of eyelashes
  • Loss of body hair
  • Loss of hair from the armpits
  • Loss of hair from genitalia


  • Redness
  • Stickiness
  • Discharge
  • Reduced vision


  • Reduced hearing
  • Dizziness


  • Mouth ulcers
  • Patches in mouth
  • Ulcers/sores on the tongue
  • Lesions on the lips
  • Swollen lymph nodes

Upper airway

  • Flu, Cold, Fatigue &/or Tiredness
  • Sore throat
  • Swollen lymph nodes

Abdominal area

  • Abdominal pain or tenderness
  • Pelvic pain or tenderness

Other genital infections which are not STIs

  • Bacterial vaginosis
  • Balanitis
  • Candida (Thrush)
  • Cervicitis
  • Gardnerella vaginalis
  • Non-gonococcal urethritis (NGU)
  • Non-specific urethritis (NSU)
  • Pelvic inflammatory disease
  • Urinary tract infection (UTI)


The complications from STIs can vary depending on the residing infection.

In the instance of Chlamydia, Gonorrhoea and Mycoplasma genitalium, the following complications may arise:

  • In men & women: SARA (Sexually Acquired Reactive Arthritis)
  • In men: Epididymitis or Epididymo-orchitis
  • In women: Pelvic Inflammatory Disease (PID)
  • In women: Infertility

In addition to the three complications above, Pelvic Inflammatory Disease (PID) is a complication in women which can lead to these further problems if left untreated:

  • Tubo-ovarian abscess (short term complication)
  • Fitz-Hugh Curtis syndrome (short term complication)
  • Infertility (long term complication)
  • Ectopic pregnancy (long term complication)
  • Chronic pelvic & back pain (long term complication)
  • Pelvic adhesions (long term complication)

Click here to learn more about PID >

An undiagnosed and/or untreated STI can be passed on from a pregnant mother to their child during birth. The newborn may experience stickiness of the eyes in the case of Chlamydia & Gonorrhoea

HIV, Syphilis & HPV can have more serious complications which can be difficult to manage when not diagnosed and treated early.

Please click on the following to learn more about their complications.


Here are images of some severe symptoms (before receiving treatment) that STIs may produce along with common dermatological problems that affect the genital area .

Please be advised that the images are highly graphic in nature.


STIs can be transmitted in the following ways:

  • Unprotected vaginal, anal or oral sex
  • Sharing of unclean sex toys (with/without a condom)
  • Very close contact with partners’ genitals
  • Infected semen and/or vaginal fluid in the eye
  • During childbirth from infected mother
  • Exposure to blood or body fluids


Risk Factors

The risk of catching an STI is not the same for everybody

In order to understand the risk of your exposure, we may try and determine whether you have engaged in any of the following activities (in no specific order):

  • You (or your partner) have multiple sexual partners
  • You (or your partner) pay for sexual activity
  • You (or your partner) have had an STI in the past
  • You (or your partner) are a Man who has Sex with other Men (MSM)
  • You (or your partner) engage in ChemSex
  • You (or your partner) are an Intravenous Drug User (IVDU)
  • You (or your partner) have engaged in sexual activity with someone with an STI
  • You have had unprotected sex with a new partner
  • You (or your partner) have unprotected sex with someone born outside of the UK in a high-risk country (the prevalence of STIs varies from country to country)

For Women, we advise further caution by ensuring you get tested (as appropriate) without delay. The key reason is that you may be subject to more serious consequences by leaving an STI untreated. This may include problems like Pelvic Inflammatory Disease (PID), infertility and complications during pregnancy.

For men with female partners, there is a lower risk of developing a serious long-term problem and they show symptoms more frequently than women. However, an important benefit of regular testing is minimising the risk of infecting their female partner(s), who might experience more serious consequences.

For men with male partners, the presence of other STIs increases the risk of acquiring HIV when exposed to it. To avoid this, regular check ups are recommended (as appropriate).

Window & Incubation Periods

The window period determines how soon after entering your body can we detect the infection.

The incubation period is the time from when symptoms may begin to appear.

If you would like to learn more about the window & incubation periods of individual STIs, please click on ‘see more details’.

Important window periods to know

Chlamydia & Gonorrhoea - 14 days

Routine Check: Chlamydia, Gonorrhoea, HIV & Syphilis - 45 days

High Risk Exposure to HIV, Syphilis, Hepatitis B/C - 90 days

Page reviewed by Dr. Manoj Malu (Clinical Director)

Last reviewed date: 3 March 2020
Next review due: 3 March 2023

Whilst this content is written and reviewed by sexual health specialists, it is for general guidance only. It is not intended to replace the advice of your clinician.

References & Further Reading