STI tests after a one-night stand: why they are important

March 27, 2025
Posted by Anna Röll

March 27, 2025

A one-night stand (ONS) is a one-time, usually spontaneous sexual encounter without a long-term commitment. These encounters can be exciting but also carry risks, as sexually transmitted infections (STIs) often have no symptoms and can be transmitted unnoticed. Condoms offer protection against many STIs but do not provide complete protection. An STI test provides clarity about potential infections, protects your health, and prevents you from unknowingly transmitting an infection to others.

Why is an STI test important after a one-night stand?
When can I get tested for an STI after a one-night stand?
Where and how can I get tested for STIs, and is anonymous testing possible?
Which STIs should I be tested for?
What are the most common classic symptoms of an STI?
What factors increase the risk of contracting an STI—even during a one-night stand?
How can I effectively protect myself from STIs during a one-night stand?
Summary

Why is an STI test important after a one-night stand?

An STI test is a simple yet effective measure to protect your health, take responsibility, and eliminate uncertainty after a one-night stand. Even if protection such as condoms was used, an STI cannot be ruled out if the STI status of the partners is unknown. The main reasons for getting tested can be grouped into three main categories:

Protect your own health.

Detect asymptomatic infections: Many STIs like chlamydia or gonorrhoea often show no visible symptoms. About 50% of men and 70% of women infected with chlamydia do not show any symptoms (Mayo Clinic, 2024). A test is the only way to know for sure if an infection is present.
Avoid long-term consequences: Untreated STIs can lead to serious long-term effects such as infertility, chronic pain, or organ damage. They increase the risk of HIV and cancers like cervical cancer (in the case of HPV) and can cause complications during pregnancy (NHS, 2024).
Condoms do not provide complete protection: Condoms only protect the areas they cover. They are particularly effective against infections transmitted through bodily fluids like semen, vaginal secretions, or blood (e.g., HIV, chlamydia, gonorrhoea). However, infections like herpes, HPV, or syphilis can also be transmitted through skin contact outside the condom-covered area. Improper use, such as a torn condom, can further increase the risk (WHO, 2024).

Take responsibility for others.

Prevent the spread of infections: An STI test helps prevent the transmission of infections by detecting asymptomatic cases and clarifying one’s STI status.
Inform sexual partners: If you test positive, current and previous partners should be informed so they can also get tested and treated (NHS, 2024).

Benefit from psychosocial reassurance.

Clarity and relief: After unprotected sex or condom failure, a test provides certainty and reduces anxiety or uncertainty.
Contribute to STI prevention: Early detection and treatment of infections help reduce the spread of STIs in society. In 2022, the number of reported STI cases in Europe increased significantly; for example, reported cases of gonorrhoea (also known as “the clap”) rose by 48% compared to the previous year (ECDC, 2024).

Would you like to learn more about STI transmission? Read our blogs: “How are STIs transmitted?” and “Can you catch an STI from oral sex?”

When can I get tested for an STI after a one-night stand?

An STI test after a one-night stand is sensible, but it's important to consider the diagnostic window before testing. The diagnostic window refers to the time between infection and the point at which the infection becomes reliably detectable. Testing too early can lead to false-negative results. Respecting the diagnostic window ensures reliable results. However, in the case of acute symptoms such as itching, discharge, or skin changes, you should consult a doctor immediately—regardless of the recommended waiting period.

Overview: Diagnostic windows for STI tests

STI	Diagnostic Window	Recommended Testing Time
Chlamydia	1–2 weeks	From 2 weeks after contact
Gonorrhoea	1–2 weeks	From 2 weeks after contact
HIV	6 weeks	From 6 weeks (antibody test)
Syphilis	3–6 weeks	From 6 weeks after contact
HPV	Weeks to months	Routine screening
Herpes	2–12 days	When symptoms appear

HPV is usually only detected during routine screenings or when visible symptoms like warts appear, as there are no standard blood tests and the infection often goes unnoticed. Herpes can be diagnosed through a swab of visible blisters or sores but is difficult to detect without symptoms.

Respecting the diagnostic window ensures reliable test results. However, in cases of acute symptoms such as itching, discharge, or skin changes, a doctor should be consulted immediately—regardless of the waiting period (Mayo Clinic, 2023).

Where and how can I get tested for STIs, and is anonymous testing possible?

In Germany, there are several ways to get tested for STIs. General practitioners and specialists such as gynaecologists or urologists offer comprehensive testing and counselling—although usually not anonymously. Health departments and counselling centres are other options. For 100% discretion, online test kits—such as those offered by Homed-IQ—can be used. All Homed-IQ results are analysed in ISO-certified laboratories also used by clinics and medical practices.

Which STIs should you get tested for?

After a one-night stand, it is generally recommended to get tested for all relevant and common STIs—while taking the diagnostic window into account. The risk of infection depends on the type of sexual contact (vaginal, anal, or oral), the health status of the partner(s), and other individual factors. To be on the safe side, tests for chlamydia, gonorrhoea, syphilis, HIV, hepatitis B and C, herpes, and HPV are recommended. Even without symptoms, testing is important, as many STIs initially go unnoticed (CDC, 2024).

What are the most common classic symptoms of an STI?

The incubation period—the time between infection and the appearance of symptoms—varies greatly depending on the infection and ranges from a few days to several weeks. Moreover, many STIs show no noticeable symptoms and remain undetected. If symptoms do occur, the following are the most common:

Unusual discharge from the vagina, penis, or anus
Pain or burning during urination
Itching, redness, or blisters in the genital area
Swollen lymph nodes, especially in the groin
Lower abdominal pain in women
Skin rashes or sores, often painless (e.g., syphilis)
Pain or bleeding during sexual intercourse

In our blog “Recognising STIs: How do I know if I have a sexually transmitted infection?”, you’ll find detailed information on how to spot an STI. If symptoms appear, seek medical advice immediately (Cleveland Clinic, 2021)

What factors increase the risk of an STI—even during a one-night stand?

The risk of a sexually transmitted infection (STI) increases due to certain behaviours and circumstances:

Unprotected sex: Skipping protection like condoms significantly increases the likelihood of transmission.
Frequent partner changes: The more partners, the higher the risk—especially without regular testing.
Unknown health status of partner(s): Without knowing your partner’s STI status, the risk remains unclear and often underestimated.
Type of sexual contact: Anal sex carries the highest risk due to the sensitive mucosa, followed by vaginal and oral sex.
Wounds or mucosal damage: Injuries to the skin or mucous membranes facilitate pathogen entry.
Previous STIs: Previous infections may alter mucosal surfaces, increasing susceptibility to new infections.
Alcohol or drug use: These substances promote risky behaviours, such as unprotected sex. Studies show that drug use during sex is linked to inconsistent condom use and frequent partner changes (Evers et al., 2023).
Lack of vaccination: Without vaccines, the risk of certain infections like HPV or hepatitis B increases.
Disrupted vaginal flora: In women, an imbalance in vaginal flora can increase the risk of infection.

These factors highlight the importance of protection and responsible sexual behaviour (YaleMedicine, 2024).

How can I effectively protect myself from an STI during a one-night stand?

A one-night stand can be a positive experience if the sexual health of all parties is taken seriously. Being aware of the risks and following preventive measures is key to enjoying the encounter without worries and avoiding infections. Simple precautions can significantly reduce risk. The most important protection measures are clearly presented in the figure.

Source: Own illustration based on NHS, 2023

Summary

An STI test after a one-night stand is important because many infections are asymptomatic and can only be detected through testing. While condoms offer protection, they do not prevent all infections—such as herpes or HPV, which can be spread through skin contact. Regular testing, vaccinations, condoms, and responsible behaviour greatly reduce the risk. If symptoms occur or if risky behaviour has taken place, testing should be done promptly to protect your health and that of your sexual partners.

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About the author

Anna Röll

Anna is a trained nurse and health economist with a focus on epidemiology and combines her medical and scientific interests. Her goal is to raise awareness of medical content and to communicate it in an understandable way. What she appreciates most about living in Amsterdam is the open-minded, active attitude of the people, the markets and the great nature in the area.