How soon do STI symptoms appear?

In this guide, we look at how soon STI symptoms appear, common symptoms to look out for, and how to get tested for STIs.

What is a sexually transmitted infection (STI)?

Sexually transmitted infections (STIs), also known as sexually transmitted diseases (STDs), are infections that are most commonly passed on during sexual contact.

Many STIs/STDs are spread via infected bodily fluids such as vaginal fluids, anal secretions, semen, and blood. However, some STIs can be passed on during skin-to-skin contact with an infected person.

Pregnant and breastfeeding mothers can also pass certain STIs on to their babies.

An STI/STD test is the best way to find out for certain if you have an STI. You might not experience symptoms even if you do have an infection, so it is important to get tested regularly, to ensure you remain clear of any infections.

Testing also helps prevent the spread of infections to other people and ensures any infections can be diagnosed and treated early before symptoms worsen.

If you think you might have an STI and are experiencing symptoms that are causing pain or discomfort, we strongly advise that you contact your GP or local sexual health clinic for advice and guidance on testing and treatment options.

How soon do STI symptoms appear?

How soon STI/STD symptoms appear depends on a variety of factors including the type of infection a person has, and when they were first infected.

The time it takes from when a person is first infected to when they might start to experience symptoms is called the ‘incubation period’. However, some people may never experience any symptoms even if they have an infection.

Incubation periods can vary from as little as one day to months or even years, depending on when the body begins to show symptoms and produce markers of the infection, such as antibodies.

Below is an overview of some of the most common STIs, along with the average incubation period for each infection, and the type of symptoms that an infected person may experience.

Chlamydia

What is it?

Chlamydia is an infection caused by Chlamydia trachomatis bacteria. It is usually spread via sexual contact and genital fluids (semen or vaginal fluid).

It is especially common among sexually active teenagers and young adults, and most people will not notice any symptoms, meaning that it is often transmitted by people who do not even know they are infected.

However, symptoms can also appear many months after a person is first infected once the infection has spread to other parts of the body.

Incubation period: 7-21 days

Symptoms:

• Unusual discharge
• Burning or pain when you urinate
• Itching or burning genitals
• Pain during sex
• Painful periods and/or bleeding between periods.

Gonorrhoea

What is it?

Gonorrhoea is an STI caused by Neisseria gonorrhoeae bacteria. The infection is easily passed on through sexual intercourse, including vaginal, anal, and oral sex, and is mainly found in discharge from the penis and in vaginal fluid.

Incubation period: 1-14 days

Symptoms:

• Unusual discharge
• Burning or pain when you urinate
• Painful or swollen testicles
• Inflammation of the foreskin and penis
• Pain during sex
• Bleeding between periods
• Belly pains

Mycoplasma genitalium

What is it?

Also known as Mgen, mycoplasma genitalium is a bacterial STI that can infect the genitals and urinary tract. It can be passed on during sexual intercourse or during genital touching without penetration.

If left undiagnosed or untreated, Mgen can cause long-term health complications including sexually acquired reactive arthritis (SARA) and a painful swelling and infection of the testicles in men, and pelvic inflammatory disease in women, which can damage the fallopian tubes, leading to infertility.

Because the symptoms of Mgen are so similar to chlamydia, it is important that people with symptoms are tested for both Mgen and chlamydia, so that an Mgen infection can be confirmed or rule out.

It is also extremely important for anyone being treated for STIs such as Mgen to finish their full course of antibiotics. If the infection is not cleared, this can cause it to become resistant to antibiotics over time, making it much harder to treat.

Incubation period: 7-21 days

Symptoms:

• Swelling of the urethra
• Unusual discharge
• Burning or pain when you urinate
• Inflammation of the foreskin and penis
• Pain during sex
• Bleeding from the vagina after sex

Trichomoniasis

What is it?

Trichomoniasis is an STI caused by the parasite Trichomonas vaginalis. It is usually spread by having unprotected sex (without a condom) but can also be spread by sharing sex toys that have not been washed or covered with a condom before use.

Many people infected with trichomoniasis will not experience any symptoms at all.

Incubation period: 5-28 days

Symptoms:

• Itching or irritation inside the penis
• Unusual or smelly discharge
• Burning or pain when you urinate
• More frequent urination
• Genital itching, burning, redness or soreness
• Pain during or after sex
• More frequent urination

Herpes (genital/oral)

What is it?

Herpes is an STI that is typically passed on through vaginal, anal or oral sex. However, it can also be passed on during non-sexual skin-to-skin contact with an infected person.

There are two types of herpes infection, both of which are caused by the herpes simplex virus: HSV-1, which typically causes oral herpes (e.g. cold sores) but can also cause genital herpes, and HSV-2, the more common cause of genital herpes.

Many people with herpes will not experience symptoms when they are first infected. However, the virus remains in the body and can cause symptoms weeks, months, or years after first exposure.

Incubation period: 2-14 days

Symptoms:

• Small sores
• Ulcers and/or wart-like growths on the genitals and/or other parts of the body
• Itching or burning around the genitals
• Painful urination
• Unusual vaginal discharge

Syphilis

What is it?

Syphilis is an STI caused by Treponema pallidum (T. pallidum) bacteria, and develops in four stages: primary syphilis, secondary syphilis, latent syphilis and tertiary or late syphilis.

It is typically passed on to others during unprotected sexual activity (vaginal, anal, oral sex). However, it can also be passed on during non-sexual skin-to-skin contact with an infected person.

If left undiagnosed or untreated, it can cause serious and potentially life-threatening problems.

Incubation period: 2 weeks – 20 years (type dependent)

Symptoms:

• Small sores
• Ulcers and/or wart-like growths on the genitals and/or other parts of the body
• A rash on the palms of the hands/soles of the feet
• Swollen glands
• Patchy hair loss
• Flu-like symptoms including high temperature, headaches, and tiredness

If you are experiencing symptoms that could indicate you have an STI, that are causing you pain or discomfort, or that require a face-to-face examination, we strongly advise that you contact your GP or local sexual health clinic for advice and guidance as soon as possible.

What are the most common STI symptoms?

The symptoms of an STI can vary depending on the type of infection a person has, and how long it has been since they were first infected.

However, there are certain symptoms that can be seen across several STIs/STDs. Some common symptoms that can indicate an STI include:

• Unusual discharge
• Burning or pain when you urinate
• Itching or burning genitals
• Pain during sex

For more information on the signs and symptoms of different STIs, visit www.sexwise.org.uk.

Can STI symptoms appear the next day?

Although it is possible for STI symptoms to appear the next day, it is highly unlikely.

This is because every STI/STD has a different incubation period: the length of time it takes from when a person is first infected, to when they first begin to experience symptoms.

For the majority of STIs, symptoms can take several days or weeks to appear, but this can extend to months and even years depending on the infection.

Additionally, many people with STIs will only experience mild symptoms, or no symptoms at all. This means that the chances of passing an infection on to someone else during sexual activity are much higher.

If you are experiencing symptoms that could indicate an STI, or are causing you pain or discomfort, speak to your GP or local sexual health service as soon as possible for guidance on next steps. 

Do STIs always show symptoms?

No, STIs do not always show symptoms. In fact, many people with an STI/STD will have no symptoms at all. This is known as being asymptomatic.

However, even when a person does not have any symptoms, it is still possible to pass an infection on to sexual partners, especially if having unprotected sex.

Regular STI testing – even if you do not have symptoms – can help you remain clear of any infections. Testing for STIs can also help you get diagnosed more quickly, reducing the risk of you passing the infection on to someone else, and enabling you to seek treatment before symptoms worsen to prevent long-term complications.

AlphaBiolabs offers a range of home STI tests that are suitable for people with or without symptoms. Please note, you must be at least 16 years of age to purchase an STI test from AlphaBiolabs.

For further advice on STI testing without symptoms, speak to your GP or local sexual health clinic. You can also visit www.sexwise.org.uk for further information.

How can I get tested for STIs/STDs?

Regular STI testing can help you keep your sexual health in check and ensure any infections are detected early, so that you can seek the correct treatment via your GP or local sexual health clinic.

Many people with an STI/STD do not display any symptoms (are asymptomatic). This makes regular testing even more important for reducing the spread of infections.

AlphaBiolabs offers a range of home STI tests for people with and without symptoms, starting from just £29.

Depending on which test you choose, you will need to provide a urine sample, vaginal swab sample, lesion swab sample or a finger-prick blood sample for analysis at our UK laboratory.

Our test kits have been designed to enable you to collect your own sample quickly and discreetly at home.

However, if you are experiencing symptoms that are causing severe pain or discomfort, or that require a face-to-face examination, we advise you to contact your GP or local sexual health clinic as soon as possible.

Please note, you must be at least 16 years of age to purchase a home STI test kit from AlphaBiolabs.

• NHS Health A to Z – STIs
• Sexwise
• MayoClinic.org – Sexually Transmitted Diseases (STDs)
• Healthline – How long does it take for STD symptoms to appear?