How to carry out an STI test

Sexually transmitted infections (STIs) are often insidious: They frequently present without symptoms but can lead to serious health consequences. An STI test provides clarity and protects both your health and that of your partner. Whether it’s a blood test, urine sample, or swab – modern testing methods make diagnosis simple and effective. In this article, you’ll learn why regular testing is essential, how the process works, and what at-home options are available.

Table of Contents

• What is an STI test?
• How does an STI test work?
• How do I know if I need an STI test?
• What happens if the test is positive for an STI?
• Summary

What is an STI test?

An STI test (test for sexually transmitted infections) is used to diagnose conditions such as chlamydia, gonorrhea, HIV, or syphilis. The testing methods vary depending on the type of STI. In general, a physical examination is combined with blood, urine, or swab samples for an accurate diagnosis. Regular testing is important to detect infections early, begin appropriate treatment, and reduce the risk of transmission. These tests are especially useful when you have multiple sexual partners or experience symptoms such as unusual discharge or pain (Cleveland Clinic, 2023).

At-home STI tests

At-home STI tests, such as the Basic-4 STI Test, the Chlamydia and Gonorrhea Test, or the Complete STI Test from Homed-IQ, allow for simple and discreet diagnosis of STIs directly from home. The tests are easy to perform and anonymous, and samples are sent to ISO-certified laboratories also used by physicians for reliable analysis. Results are available within a few business days and can be accessed online. Additional support is provided through detailed test instructions on Homed-IQ’s YouTube channel. In case of uncertainty or abnormal results, consulting a physician is recommended.

How does an STI test work?

The diagnostic process begins with a medical history, during which symptoms and personal risk factors are assessed. This includes questions about current complaints, past infections, and sexual practices. This is followed by sample collection and a physical examination, where blood, urine, or swabs from the genitals, throat, or anus are taken to detect specific pathogens. Physical exams may also reveal visible abnormalities such as skin changes or inflammation. The collected samples are analyzed in the lab for bacteria, viruses, or fungi that may be causing the symptoms. After testing, the findings are discussed, the diagnosis is explained, and appropriate treatment – such as antibiotics or antiviral medications – is initiated (Cleveland Clinic, 2023).

Swab test

A swab is performed using a sterile cotton swab to collect mucus membrane or secretion samples. Depending on the suspected infection, samples are taken from the urethra, vagina, anus, or throat. This process takes only a few seconds, is generally painless, and targets contact areas of sexual activity.

STIs for which swab tests are used:

• Chlamydia and gonorrhea

• Trichomoniasis

• Herpes

• Human papillomavirus (HPV)

• HIV

• Syphilis

Source: MedlinePlus, 2024; Cleveland Clinic, 2023 

Urine sample

Testing for STIs using a urine sample requires providing a small amount of urine in a sterile container. For accurate results, the first morning urine or the initial stream is often used. The sample is then analyzed in a laboratory, especially for infections in the urinary or genital tract.

STIs for which urine samples are used:

• Chlamydia and gonorrhea

• Trichomoniasis

Source:  MedlinePlus, 2024; Cleveland Clinic, 2023

Blood sample

An STI test via blood sample requires drawing a small amount of blood from a vein, usually from the crook of the arm or via a finger prick. The sample is taken under sterile conditions and analyzed in a lab to detect bloodborne infections or infection markers.

STIs for which blood samples are used:

• HIV

• Syphilis

• Hepatitis B and C

• Genital herpes (to determine if you’ve been exposed to the virus, even if there’s no active infection)

Source: MedlinePlus, 2024; Cleveland Clinic, 2023

How do I know if I need an STI test?

The following points may help determine whether an STI test is necessary:

Testing may be useful if you experience symptoms – note that many STIs are asymptomatic:

• Unusual discharge (from the vagina, penis, or anus)

• Pain or burning during urination or sex

• Itching or irritation in the genital or anal area

• Sores, blisters, or warts on the genitals

• Blisters or warts, rashes in the mouth or throat

• Fever, fatigue, or skin rashes

• Swollen lymph nodes

Source: NHS, 2024 

Testing is particularly recommended in high-risk situations, especially when:

• Engaging in unprotected sex (vaginal, anal, or oral), as pathogens can easily be transmitted

• Having multiple sexual partners or not using protection like condoms

• Beginning a new sexual relationship – testing should occur before the first unprotected encounter since infections are often asymptomatic

• Using drugs, especially when sharing needles or other items, which increases the risk of infections such as HIV or hepatitis C

• Belonging to certain groups, such as men who have sex with men (MSM), where more frequent testing is recommended

Source: CDC, 2024 

Routine STI testing is an important part of preventive health care

Routine testing is advised even in the absence of symptoms, as many STIs remain undetected for a long time but are still contagious. According to health guidelines, women under 25 who are sexually active should be tested for chlamydia regularly. Testing can be done annually or with each new partner and helps detect, treat, and prevent the spread of infections. Routine STI screening is also important before planning a pregnancy to avoid complications (Sexual Health Clinic London, n.d.).

What happens if the test is positive for an STI?

A positive STI test result – whether from an at-home test, doctor, or test center – can initially be unsettling. However, it’s important to stay calm, as many infections are easily treatable. The next steps may include:

• Consultation: A doctor will explain the infection, possible complications, and treatment steps.

• Treatment: Depending on the infection, treatment may include antibiotics (e.g., for chlamydia) or antiviral medications (e.g., for HIV).

• Partner notification: Sexual partners should be informed and tested to prevent further transmission.

• Follow-up testing: After treatment, repeat testing may be recommended to confirm that the infection has been successfully treated.

• Prevention: Counseling on protective measures, such as consistent condom use, to prevent future infections.

Source: Cleveland Clinic, 2023

It’s important to note that false-positive test results are possible, especially if the test is conducted outside the diagnostic window. The diagnostic window is the time between exposure and the point at which a test can reliably detect an infection. If testing occurs too early, the results may be inaccurate. In such cases, follow-up tests or a doctor’s consultation is advised to confirm the diagnosis and avoid unnecessary treatment (Deutsche Apotheker Zeitung, 2019).

Summary

Sexually transmitted infections (STIs) are often asymptomatic but can lead to serious health issues. STI testing is essential for early detection, treatment, and preventing further transmission. Testing procedures include blood, urine, and swab samples and are easy to carry out. At-home STI tests offer a discreet way to diagnose STIs from the comfort of home. Products like the Basic-4 STI Test, the Chlamydia and Gonorrhea Test, and the Complete STI Test from Homed-IQ provide simple sampling options. While testing is especially important for those with symptoms, it is recommended that all sexually active individuals undergo routine screenings to detect infections early and curb their spread. A positive test result should be confirmed by a physician, followed by appropriate counseling and, if necessary, treatment.