STI Testing Before a New Relationship: When and What to Test For

STI testing before a new relationship is increasingly recognised as a routine part of responsible sexual health care. For many adults in the UK, getting screened before becoming exclusive with a new partner is a practical step — one that provides reassurance and supports informed decision-making about intimacy.

Choosing to test is not a sign of suspicion or mistrust. It reflects a mature approach to sexual wellbeing. Many STIs can be present without symptoms, and previous exposures — even from months or years ago — can remain undetected without appropriate screening. Testing before a new relationship allows both partners to begin on a clear footing.

The timing of your test matters. Window periods mean that some infections cannot be reliably detected until a certain period has passed since the last potential exposure. This guide explains when to consider testing, which infections to check for, and how to approach the subject with a new partner.

Should You Get an STI Test Before a New Relationship?

There is no universal rule that requires STI testing before every new relationship. However, routine screening may be considered in a number of situations, and many healthcare professionals recommend it as good practice.

You may wish to consider testing if:

• You have had previous sexual partners since your last STI test
• It has been some time since your last screening — particularly if several years have passed
• You have not consistently used condoms in past relationships
• You have experienced any symptoms that could suggest an STI, even if they resolved on their own
• You and your partner are planning to stop using condoms and rely on other forms of contraception

STI testing before a new relationship is ultimately about clarity and confidence. It allows you and your partner to make informed choices and is widely viewed as a responsible step rather than one that implies any doubt about the relationship.

When Is the Right Time to Test Before Becoming Exclusive?

The ideal time to test is before you stop using condoms with a new partner. This means allowing enough time after your last potential exposure for the relevant window periods to elapse.

If you have recently had sexual contact with a previous partner, testing immediately may not detect all infections. The following table outlines typical timeframes for reliable detection:

Testing too early may result in false-negative results. Repeat testing may sometimes be recommended, particularly if the last exposure was recent.

For many couples, the practical approach is to test after the longest relevant window period has passed — typically around six weeks after the last potential exposure. This allows confidence in the reliability of results across all commonly tested infections.

It is also worth noting that many STIs can be present without causing any noticeable symptoms. Learn more about asymptomatic STDs and why screening is important even when you feel well.

What STI Tests Should You Consider Before a New Partner?

The specific tests appropriate for you depend on your sexual history and any symptoms. Below are the infections most commonly included in pre-relationship screening.

Chlamydia and Gonorrhoea

Chlamydia and gonorrhoea are among the most frequently diagnosed STIs in the UK. Both are bacterial infections that can be transmitted through vaginal, anal, or oral sex, and both are commonly asymptomatic.

Chlamydia produces no symptoms in around 70% of women and 50% of men, making it particularly important to test for routinely. Testing typically involves a simple urine sample or swab and results are usually available within a few days.

HIV

HIV testing is an important part of any comprehensive STI screen. The risk of HIV depends on individual history, including previous sexual partners and the type of contact involved. A 4th generation HIV blood test can reliably detect infection from approximately 18 to 45 days after exposure.

For earlier detection — for example, if your last potential exposure was more recent — an HIV PCR test can detect the virus from around 10 to 14 days after exposure, though this test is typically more expensive.

Syphilis

Syphilis rates have been increasing in the UK in recent years. The infection can be transmitted through vaginal, anal, or oral sex and may not produce noticeable symptoms in its early stages. Blood testing for syphilis is generally reliable from around three to six weeks after exposure.

Herpes

Routine blood testing for herpes is not widely recommended in the absence of symptoms. This is because herpes blood tests can be difficult to interpret and may cause unnecessary anxiety. However, if you have ever experienced genital blisters, sores, or tingling, a swab test during an active episode is the preferred approach.

Mycoplasma Genitalium

Mycoplasma genitalium is a bacterial infection that has received increasing attention in recent years. Testing may be clinically appropriate in some circumstances, particularly if symptoms such as urethritis or pelvic inflammatory disease are present. However, routine screening for mycoplasma in the absence of symptoms is not universally recommended and should be discussed with a healthcare professional.

What If You Feel Completely Well?

Feeling healthy and symptom-free is, of course, reassuring — but it does not always mean that no infection is present. Many of the most common STIs are asymptomatic, particularly in their early stages.

Chlamydia, gonorrhoea, HIV, syphilis, and hepatitis B can all be present without producing any noticeable signs. This is precisely why testing is valuable: it provides information that symptoms alone cannot.

If you and your new partner both feel well, testing still offers meaningful reassurance. A confirmed negative result — taken after the appropriate window period — carries far more weight than the simple absence of symptoms.

For more on infections that may not produce symptoms, see our article on asymptomatic STDs.

How to Talk to a New Partner About STI Testing

Raising the subject of STI testing with a new partner can feel daunting, but in practice it is often much simpler than anticipated. The key is to frame the conversation as a shared responsibility rather than an accusation.

Some practical approaches:

• Frame it as mutual — suggest that you both get tested, rather than asking your partner to do so alone. Phrases such as "Shall we both get checked before we stop using condoms?" are collaborative and non-confrontational
• Choose a calm moment — avoid raising the topic during or immediately before sex. A relaxed setting allows for a more considered conversation
• Be matter-of-fact — treat testing as a routine health decision, similar to any other medical check-up. The more normally you frame it, the more naturally it will be received
• Avoid blame or assumptions — the conversation should focus on shared health, not on past behaviour. Statements such as "I like to get tested between partners" are neutral and personal

Many people find that their partner is relieved the subject has been raised, as they may have been thinking the same thing but were unsure how to bring it up.

NHS vs Private STI Testing Before a Relationship

Both NHS and private services provide reliable STI testing in the UK. The choice between them is a matter of personal preference and practical convenience.

NHS sexual health clinics:

• Provide free STI testing across the UK
• Available through GUM clinics and community sexual health centres
• Appointment availability may vary depending on demand and location
• Some areas offer free postal testing kits for chlamydia and HIV

Private STI clinics:

• Charge a fee for testing, with prices varying by clinic and test type
• May offer more flexible appointment scheduling, including evenings and weekends
• Some provide shorter turnaround times for results, though this is not guaranteed
• May offer a wider choice of individual tests or screening packages

Some individuals prefer private services due to scheduling flexibility or a preference for a particular clinic environment. Others prefer the accessibility and cost-free nature of NHS provision. Both pathways follow rigorous quality standards for sample collection and laboratory analysis.

Can You Have Sex While Waiting for Results?

If you have been tested and are waiting for results, you may wonder whether it is appropriate to have sex in the meantime.

This is a personal decision, but there are a few considerations:

• If you are within the window period for certain infections, your test results may not be fully conclusive. In this case, using condoms provides an additional layer of protection
• If you have any symptoms, it may be sensible to avoid sexual contact until results are available and clinical advice has been given
• If both partners have been tested and are waiting for results, mutual agreement on how to proceed is the most practical approach

Avoiding assumptions about your status — or your partner's — until results are confirmed is generally the most cautious approach. Using condoms while waiting is a reasonable and widely recommended precaution.

Frequently Asked Questions

Should both partners get tested?

Ideally, yes. Mutual testing provides the most complete picture of both partners' sexual health. If only one person tests, uncertainty remains about the other's status. Framing testing as something you both do — rather than something one person demands of the other — supports a healthier dynamic.

What if my partner refuses testing?

If your partner is reluctant to test, it may help to explain your reasons calmly and frame it as a shared health decision. Ultimately, testing is a personal choice, and no one should be pressured. However, their reluctance does not affect your ability to get tested yourself. Continuing to use condoms is a practical precaution if testing has not been completed.

Do we need to test if we used condoms previously?

Condoms significantly reduce the risk of most STIs, but they do not eliminate all risk — particularly for infections transmitted through skin-to-skin contact, such as herpes, HPV, and syphilis. If you have consistently used condoms with all previous partners, your risk may be lower, but testing can still provide additional reassurance.

How long after my last partner should I test?

For most infections, testing is reliable from around two to six weeks after the last potential exposure. HIV (4th generation) testing is usually reliable from 18 to 45 days. If your last sexual contact was very recent, your clinician may recommend an initial test followed by a repeat screen after the full window period has elapsed.

Can you trust one negative result?

A negative result taken after the appropriate window period is generally reliable. However, no test is 100% accurate in all circumstances. If the test was performed very soon after exposure — before the window period had fully elapsed — a follow-up test may provide additional confidence. Your clinician can advise on whether repeat testing is appropriate.

When Should You Seek Medical Advice Instead of Routine Testing?

In most cases, pre-relationship STI screening is a straightforward routine process. However, you should seek clinical advice rather than simply booking a routine test if you are experiencing:

• Active symptoms such as unusual genital discharge, pain during urination, or changes in the skin around the genitals
• Painful sores or ulcers on the genital area, mouth, or rectum
• Unusual rashes particularly if accompanied by fever or general malaise
• Pelvic or lower abdominal pain that could suggest an underlying infection

These situations may require clinical assessment in addition to testing. A healthcare professional can examine you, discuss your symptoms, and arrange targeted testing based on your presentation.

Confidential Sexual Health Testing in the UK

If you would like confidential STI testing before entering a new relationship, appointments are available at our UK clinic. Testing options depend on individual history and timing, and our team can advise on appropriate screening.

Whether you are looking for a comprehensive screen or a specific test, clinical support is available to help you make an informed decision. Book a confidential appointment at a time that suits you.