Sexual health when you have more than one partner

Once a relationship opens, your sexual health is linked to people you've never met: your partner's other partners, and theirs. That isn't a reason to panic. It's a reason to agree something specific rather than assuming you both mean the same thing by "being careful".

A few terms used below. An STI (sexually transmitted infection) is an infection passed on through sex or sexual contact; many have no symptoms. PEP (post-exposure prophylaxis) is HIV medicine taken after a possible exposure to stop infection taking hold. PrEP (pre-exposure prophylaxis) is medicine taken before sex to prevent HIV. A window period is the time after exposure before a test can reliably pick an infection up.

Agree the rules before anyone meets anyone

Settle safer sex before either of you sets up a profile, because vague agreements tend to fail in the moment. Cover:

• Condoms: for which kinds of sex, and with whom. Many couples keep condom-free sex for each other only.
• Oral sex: whether you'll use condoms or dental dams; the NHS advises using them for oral sex too until you've been tested.
• Testing: how often, and whether you'll both test before you start.
• Telling each other: what you'll share, and how quickly, especially if something went wrong, such as a condom splitting.
• What happens if someone breaks the agreement: for example, a pause in sex between you until you've both tested.

Write it down alongside your other boundaries. The guide to starting the conversation explains how this fits with the rest of your agreement.

An example of how to raise it, in your own words: "Before either of us meets anyone, can we agree the safer-sex side properly? I'd like condoms with anyone else every time, both of us testing before we start and then every few months, and a text the same day if anything goes wrong. What would you add?"

Testing: when and how often

Test before you start, before each new sexual relationship where you can, after any risk, and on a regular schedule you both agree. In a table:

Timing matters. The NHS says STIs can take up to seven weeks after unprotected sex to show up on a test, so a test the day after a risk may not give a reliable answer. A clinic can tell you when each test is worth doing and whether you need treatment in the meantime.

After a risk: PEP and emergency contraception

If you may have been exposed to HIV, act within hours, not days. The HSE says PEP must be started as soon as possible and within 72 hours of likely exposure, and the course lasts 28 days. In Ireland, PEP medicine is free from many sexual health and infectious disease services, or from an emergency department outside clinic hours, where an attendance fee may apply. In the UK, NHS sexual health clinics provide PEP, and also emergency contraception.

Don't wait for a test result before asking about either. They work best the sooner you start.

Free, confidential testing

Ireland

The HSE runs a free home STI testing service for anyone aged 17 or over who lives in the Republic of Ireland. You order a kit online through SH:24 at sh24.ie, giving your name, mobile number and address, and do the test at home. The kits test for chlamydia, gonorrhoea, HIV and syphilis, and you may also be offered a hepatitis B or C test. The HSE says results are usually available within 72 hours of the lab receiving your samples. A "reactive" blood result isn't a confirmed diagnosis; you'll be referred for a further test.

The home service isn't for urgent needs. If you have symptoms, contact a public STI clinic or your GP. The HSE says its sexual health services are free and confidential, with clinics in counties including Cork, Dublin, Galway, Limerick and Waterford. Free PrEP is available from public PrEP clinics to people who are eligible.

UK

NHS sexual health clinics are free, confidential and open to everyone, whatever your age, gender or sexuality. They offer STI testing and treatment including HIV tests, contraception including emergency contraception, and PrEP and PEP. Staff won't share what you discuss, including with your GP, without your permission. Free home testing kits are available in many areas, but how you get one depends on where you live. Find a clinic on the NHS website, or on NHS inform in Scotland.

Sharing results honestly

Tell your partner, and anyone else you've been with, if you test positive for something. It's uncomfortable, but it's the core of what makes ethical non-monogamy ethical: people get to make informed choices. The NHS says you should tell current partners and any ex-partners, and that a clinic can usually do it for you without naming you.

An example message, to adapt: "I've had a test result back for chlamydia and I'm being treated. The clinic says anyone I've slept with recently should get tested. I'm sorry this isn't a fun message. Shout if you have any questions."

When you meet someone new, it's reasonable to ask when they last tested and what their arrangement is. Their answer, and how they react to the question, tells you a lot. Remember that what members write on their profiles on Olivia Raven isn't checked, as staying safe on Olivia Raven explains.

Sexual assault

If something happened that you didn't consent to, it is not your fault, and help is available day and night. In Ireland, Sexual Assault Treatment Units are open 24 hours a day, 365 days a year, for anyone assaulted in the last seven days, whether or not you want to report to the Gardaí; see the HSE's SATU information. The national 24-hour Rape Crisis helpline is 1800 77 88 88.

In England and Wales, Rape Crisis runs a 24/7 support line on 0808 500 2222. In Scotland, Rape Crisis Scotland's helpline is 08088 01 03 02. NHS sexual health clinics also help after rape or sexual assault. In an emergency, call 999 or 112 in Ireland, or 999 in the UK. Our first-meeting guide covers meeting safely.

Keeping it part of the conversation

Treat sexual health as an ordinary item in your check-ins, not a crisis topic. If it does cause friction, read jealousy in open relationships, because worry about health is sometimes jealousy in disguise, and the other way round.