STI Test: Everything You Need to Know

STI Test: Everything You Need to Know

This article was written in collaboration with Yoxly, a sexual health remote diagnostic service offering at-home test kits that grant you peace of mind through convenience, privacy, accessibility, and control.

Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases  (STDs), are a common health concern for many individuals, and it's essential to get tested regularly to maintain good sexual health.

However, with a range of tests available, it can be difficult to determine which one is right for you. In this article, we will explore common STIs, including chlamydia, gonorrhea, syphilis, and HIV, and the various tests available for each. We will also look at their accuracy, and when they should be taken, helping you make an informed decision about which test is right for you.

Before we get started, let’s clear up the difference between STIs and STDs.

What is the difference between STIs and STDs?

The terms "sexually transmitted infection (STI)" and "sexually transmitted disease (STD)" are often used interchangeably to refer to conditions that are spread through sexual contact.

However, there is a subtle difference between the two.

What are sexually transmitted infections (STIs)?

An STI refers to an infection that is transmitted through sexual contact, regardless of whether it causes symptoms or not.

Some STIs, such as chlamydia, can be entirely asymptomatic. It is still possible to pass on an STI, even if you have no symptoms.

What are sexually transmitted diseases (STDs)?

An STD, on the other hand, occurs when an STI develops into a disease, meaning there are symptoms or health consequences.

For example, untreated syphilis can lead to serious health problems such as heart disease and brain damage; in this case, it is considered an STD.

In summary, all STDs are caused by STIs, but not all STIs become STDs. It's important to get tested regularly to detect and treat STIs as soon as possible to prevent the development of problematic STDs and maintain sexual health.

A note on the use of "STD" and "STI" in this article

However, “STD” has been around longer, and many people use this term in health centers and when searching for information on the internet.

As such, to ensure this guide reaches those looking for information, we will use STDs as the primary term and include STI next to it when that's the more accurate term.

What causes STDs and STIs?

STDs/STIs have 3 main causes:

  • Bacteria (which include chlamydia, gonorrhea, and syphilis)
  • Viruses (which include the herpes simplex virus, HPV, and HIV)
  • Parasites (e.g.,  trichomonas vaginalis, and pubic lice)

If left untreated, STIs can cause serious health problems, such as infertility, pelvic inflammatory disease, and in some rare cases, death.

What are common STD/STI symptoms?

Some STIs may not show any signs or symptoms.

It is, therefore, important to get tested regularly if you are sexually active and to practice safe sex to reduce your risk of contracting an STI.

STI/STD symptoms include:

  • Lumps, warts, bumps, or skin growth around the genitals
  • A rash or sores around the genitals
  • Pain while peeing
  • Itching around the genitals or anus
  • Unusual vaginal discharge or bleeding
sexually transmitted infections symptoms

What STIs should you be tested for?

Here is a set of guidelines for specific STIs that can help you decide which STIs you should consider getting tested for.

National guidelines indicate anyone who has had unprotected (condomless) sex should be tested for chlamydia, gonorrhea, syphilis, and HIV.

Certain individuals are also recommended to be tested for hepatitis B, for example, men who have sex with men, intravenous drug users, sex workers, and people who have been sexually assaulted.

Other tests, such as hepatitis C and hepatitis A may be recommended based on risk factors such as having another infection or having sexual contact with someone with a known infection.

At Yoxly, the standard STI testing kit checks for six infections (chlamydia, gonorrhea, syphilis, trichomonas, hepatitis B, and HIV). A comprehensive STI test kit also checks for hepatitis C and mycoplasma genitalium.

Individuals with symptoms (e.g. genital ulcers) may be recommended additional tests, such as testing for herpes simplex virus (HSV).

What are the different types of STI tests?

The main types of STI tests are:

  • Blood tests
  • Urine tests
  • Swab tests
  • Cervical smears
  • Physical examination
tests for sexually transmitted infections

What is the most common STI test?

The most common type of STI test is a combined test, screening for four sexually transmitted infections: chlamydia, gonorrhea, syphilis, and HIV.

This test is usually performed by collecting a urine sample and/or a swab from the vagina, and a blood sample.

Cervical screening is recommended every 3–5 years for people with a cervix aged 25–64. Cervical smears check for certain strains of human papillomavirus (HPV) that are known to increase the risk of cervical cancer. HPV is not routinely tested for on an STI test.

Who should get tested for STIs?

As a set rule, if you've had sexual contact with another person, then it's important to get tested for STDs. This is true even if you don't have any symptoms.

Anyone sexually active should consider getting tested, even if they are using barrier contraception.

Furthermore, if you have had unprotected (condomless) sex, testing is recommended. Knowing your STD status is one of the best ways to protect your sexual health and the health of your partners.

When should you get tested?

It is recommended that sexually active individuals get tested for sexually transmitted infections (STIs) at least once a year, or more frequently, depending on their risk factors and sexual behavior.

Some specific circumstances that may indicate the need for STI testing include:

  • Starting a new sexual relationship
  • Having had unprotected sexual activity
  • Having multiple sexual partners or being in a polyamorous relationship
  • Having symptoms of an STI (such as itching, discharge, pain, or blisters)
  • Having a partner with an STI

However, there are other times when you should consider getting an STI test, such as:

  • If you are having difficulty conceiving or are thinking of undergoing fertility treatment
  • During pregnancy
  • If you have been sexually assaulted or raped.

Where can someone get an STI test?

Getting an STD test is easier than you think! There are several options available depending on where you live and what is most convenient for you.

There are several options for getting tested for sexually transmitted infections (STIs):

  • GP surgery: A person can visit their general practitioner (GP) for STI testing.
  • Sexual health clinics: Also referred to  as genitourinary medicine (GUM) clinics, these are located throughout the UK and offer confidential STI testing and treatment
  • Online services: Online STI testing kits can be ordered straight to your home for self-sampling, and sent to a laboratory for analysis.

Similarly to the UK, if you are based in the US, you can visit your primary care physician, or a sexual health clinic or order a test online.

Access to STI testing in other countries may vary.

How to prepare for your STD and STI test?

Note: Different STD and STI tests (blood test, vaginal swab, urine) require different methods, and as such, might require different preparation methods. Talk to your STI test provider about what tests are necessary based on individual risk and symptoms.

Here are some general considerations (note these will vary according to the test)

  • Timing: Depending on the type of test, there may be specific timing considerations. For example, some infections may not show up on a test right away, due to the window period. In addition, some tests may require you to not pass urine for two hours before obtaining a sample.
  • Avoid douching or using lubricants before sampling: Douching or using lubricants before certain tests, such as a vaginal swab, may affect test results
  • Make sure you have read and understood the instructions for the collection of your samples before you get started.

Be open and honest with your healthcare provider: Provide a truthful and accurate sexual history, including information about partners and the use of condoms, to help guide testing decisions.

How do I do an STI test at home?

When you purchase an at-home STI testing kit from Yoxly, it includes detailed instructions taking you step-by-step through the process of collecting your samples. There is also a beginner’s guide to at-home STI testing available to read.

For collecting a vaginal sample; you will carefully insert the cotton tip of the swab about 5 centimeters into the vagina. You will gently rotate the swab for 30 seconds before withdrawing it and placing it into the collection tube.

For a urine sample, you’ll be sent a cup with which to collect your sample, which is then transferred into the collection tube, making sure to fill it to the specified line.

If you’ve chosen a test that requires a blood sample, you’ll use a small lancet to prick the skin and fill two collection tubes with your sample.

When are STD and STI tests most accurate?

The accuracy of STD and STI tests can vary depending on several factors:

  • The type of test
  • The specific STD/STI being tested for
  • The stage of any infection
  • The presence of symptoms
  • The time elapsed between exposure and taking the test

For example; the accuracy of some tests, such as blood tests, can be affected by the length of time that has passed since a potential exposure to an STD. Testing soon after exposure may be too early to yield an accurate result due to the window period (the period between exposure to an infection, and when a test can accurately detect the presence or absence of the infection). The window period of some STIs such as HIV can be several months. See Yoxly’s article on Incubation, Latency, and Window Periods for more information on when STI tests are most accurate.

Factors that may impact the accuracy of an STI test

Do you need to take an STD/STI test more than once?  

Some STIs, such as gonorrhea, HIV, and syphilis, may require a repeat follow-up test to confirm the initial result and guide treatment.

If you have taken a test soon after potential exposure to infection, it may be too soon to be accurate. In this case, it is recommended to repeat the test when you are out of the window period.

What should you do if you test positive for an STI?

If you test positive for an STI, the most important thing to do is to contact your doctor right away to discuss treatment options. At Yoxly, we support you in locating your most convenient healthcare provider, ensuring no delays in receiving treatment.

Frequently asked questions about STI testing

How long do STD/STI tests take?

STD/STI tests are quick and easy to do, and the results are usually available within a few days. With a test from Yoxly, your kit is delivered discreetly to your address within 24–48 hours, and you can collect your samples right away. You will post your samples to the lab using the enclosed, pre-paid envelope.

Your results become available in your secure Yoxly account portal within just a few days, and you’ll be notified via email as soon as they are ready to view.

How much does STI testing cost?

STI testing is available free of charge from your local sexual health clinic or general practitioner. Online at-home STI tests are available from Yoxly, from as little as £39. This includes free delivery and return postage.

Can I take an STD test on my period?

Yes, it is possible to take an STD test during your period. However, depending on the type of test and the specific STD being tested for, menstruation can sometimes affect the accuracy of test results.

Can sexually transmitted infections (STIs) be prevented?

The best way to prevent the spread of STDs is to use condoms for every episode of intercourse., including vaginal, oral, and anal sex. Dental dams can be used during oral sex (cunnilingus).

What is the most important STD/STI to test for?

When it comes to testing for sexually transmitted diseases (STDs), there is no one-size-fits-all answer. However, one of the most important STIs to test for is Human Immunodeficiency Virus (HIV).  HIV is the virus that, if left untreated, causes AIDS.  

Testing for HIV is essential to ensure early diagnosis and treatment, which can prevent the virus from progressing to AIDS. People living with HIV who are diagnosed early and are on effective treatment have a normal life expectancy. It is also important to remember that HIV is not the only STD to test for, and it is important to discuss your sexual health with your doctor to determine which tests are right for you.

As well as HIV, we also recommend testing for the most common bacterial STIs, chlamydia, gonorrhea, and syphilis. These infections are easy to treat, and in most cases, a course of antibiotics cures the infection completely.

What are the effects of STIs on pregnancy?

Sexually transmitted diseases (STDs) can have serious effects during pregnancy. If left untreated, STDs can cause a variety of complications, including premature labor, low birth weight, and even stillbirth.

STDs can also increase the risk of miscarriage and can be passed from mother to baby during childbirth, leading to serious health problems for the baby. It's important to get tested for STDs if you're pregnant and to take the necessary steps to treat any infections that are found.

With proper care and treatment, the effects of STDs on pregnancy and the baby can be minimized.


In conclusion, taking control of your sexual health is an important aspect of overall well-being. STI testing can be an empowering tool to help you understand your sexual health and make informed decisions. With a variety of testing options available, including tests performed by healthcare providers, sexual health clinics, and at-home testing kits, there is a solution to fit every need and preference.

Just remember, have open and honest conversations with your test provider, so that they can advise you on what test is best for you.

Article in collaboration with Yoxly

Yoxly is on a mission to simplify, normalize and destigmatize sexual health. They are building an ecosystem to provide a range of remote sexual health services, designed to give you a personalized experience with more convenience, privacy, accessibility, and control.
You can learn more about them on
Or follow them on socials at @yoxlyhealth