STI Prevention: Myths vs Facts

Most of what people believe about STIs comes from school, a friend, or a search at midnight. Some of it is right. Quite a lot of it, like "I'd know if I had one", is the reason infections go unnoticed for months.

Here's the short version. STIs are caused by bacteria, viruses or parasites passed between people during vaginal, anal or oral sex, and some spread through skin-to-skin genital contact. Most cause no symptoms at all in the early stages, which is why regular testing is the single most effective prevention strategy, alongside condoms.

If you'd rather skip the reading, you can walk in to 117a Harley Street seven days a week, with no GP referral. The Bronze Screen is £250 and covers HIV, syphilis, chlamydia and gonorrhoea.

"The most effective STI prevention strategy combines barrier methods with regular screening. Most of the patients I see with complications had infections that were completely treatable. They just didn't know they had them."

Dr Mohammad Bakhtiar, Clinical Lead, Sexual Health Clinic London

How do STIs spread?

There are three main routes, and each one tells you which protection works best.

Bodily fluids. HIV, gonorrhoea, chlamydia and hepatitis B pass on through semen, vaginal fluids and blood. Condoms are highly effective here, because they stop the fluids being exchanged.

Skin-to-skin contact. Herpes (HSV), syphilis and HPV spread through direct contact with infected skin, sores or warts, including areas a condom doesn't cover. That's why condoms reduce the risk of these infections rather than remove it.

Shared items. Some infections, particularly trichomoniasis, can pass on through shared sex toys. Hepatitis B can survive on surfaces outside the body for up to seven days.

What actually prevents STIs?

No single method gives 100% protection against every STI. What works is a combination.

Condoms

Condoms are the most accessible and broadly effective barrier. Used consistently and correctly, they give a high level of protection against the infections carried in bodily fluids: HIV, gonorrhoea, chlamydia and trichomoniasis.

For herpes, syphilis and HPV, which spread skin to skin, they cut the risk without removing it, because they can't cover every patch of skin that might be infected. A review of prospective studies in the Bulletin of the World Health Organization linked condom use with significant protection against chlamydia, gonorrhoea, HSV-2 and syphilis in both men and women.

A few practical points. Latex and polyurethane condoms both protect against STIs, while lambskin condoms let viruses through, so they aren't suitable for STI protection. Use a water-based or silicone-based lubricant with latex, because oil-based lubricants weaken it. And use a new condom for each act of vaginal, anal or oral sex, and whenever you switch between them.

Vaccination

HPV vaccination. The NHS offers the HPV vaccine to all children aged 12 to 13. It uses Gardasil 9, which protects against nine HPV types, including types 16 and 18, responsible for most HPV-related cancers, and types 6 and 11, responsible for most genital warts. The effect shows: UKHSA 2024 data recorded just 78 genital warts diagnoses in 15 to 17 year olds, down from several thousand before the programme began. If you missed it at school, we offer HPV testing and can advise on catch-up HPV vaccination at Medical Express Clinic.

Hepatitis B vaccination. It's effective and widely available, and recommended for anyone at ongoing risk, including people with several sexual partners and men who have sex with men. We test for hepatitis B in our Gold and Platinum screening packages.

Gonorrhoea vaccination. Since August 2025 the NHS has offered the meningococcal B vaccine to eligible groups to reduce gonorrhoea risk. Early evidence from other countries suggests around 30% protection. It works alongside condoms and testing rather than replacing them.

Regular testing

This is the most underused prevention tool of all. Most STIs cause no symptoms, particularly in women. Chlamydia, gonorrhoea, syphilis, HIV and hepatitis B can all be present for months or years without any outward sign, and you can't tell whether you or a partner has one by looking, feeling or asking.

BASHH recommends testing:

• at least once a year if you're sexually active with new or casual partners
• after every new sexual partner, ideally before you sleep with the next one
• after any unprotected sex with a partner whose status you don't know
• every 3 months, as routine screening, for men who have sex with men and have several partners

Our standard packages give results for blood tests in about 24 hours, and urine and swab results within 3 working days. If you'd like answers sooner, the FAST Screen returns all results in 6 hours: FAST Screen Simple is £350 for HIV, syphilis, chlamydia and gonorrhoea, and FAST Screen Complex is £450 with hepatitis B and C added.

Talking to partners

Talking about sexual health with a new partner before sex is simple, it needn't be formal, and it works. Knowing whether a partner has tested recently, or agreeing to test together first, cuts the risk considerably. More partners also means a higher statistical risk, which is an observation rather than a judgement: if you have several, consistent condoms and more frequent testing matter more.

Common STI myths, and what's actually true

Myth: "I would know if I had an STI"

This is the most dangerous misconception of the lot, because the majority of STIs are asymptomatic in the early stages.

Chlamydia causes no symptoms in about 70% of women and 50% of men. Gonorrhoea is silent in up to 50% of women and 10% of men with a urethral infection, and throat and rectal infections usually cause nothing at all, whatever your gender. HIV can stay symptom-free for a decade or more after the early phase. Syphilis sores are painless and in women are often hidden internally. Herpes can shed virus on about 10% of days with no visible sores. No symptoms simply means no information, and a test is how you get it.

Myth: "You cannot get STIs from oral sex"

You can. Oral sex carries a lower risk than vaginal or anal sex for most infections, but there's still a risk.

Gonorrhoea commonly infects the throat, usually without symptoms. Syphilis passes on through oral contact with a sore. Herpes, both HSV-1 and HSV-2, moves readily between mouth and genitals. Chlamydia can infect the throat, though less often, and HPV can be passed on orally and is linked to throat cancers. If you have unprotected oral sex with new partners, ask for throat swabs as well as genital tests. Our Silver, Gold and Platinum screening packages include testing at more than one site.

Myth: "Only young people get STIs"

STI diagnoses among people aged 50 to 70 have risen substantially over the past decade. UKHSA data keeps showing increases in older age groups, driven by dating after divorce, a lower sense of risk and so less condom use, and being less likely to get tested. Sex at any age carries some risk when condoms and testing aren't routine.

Myth: "I have only had one partner, so I do not need testing"

One sexual contact is enough. Your risk depends on your partner's history as well as yours, and you may not know all of it. A single episode of unprotected sex with an infected partner can pass on chlamydia, gonorrhoea, syphilis, HIV, herpes or HPV.

Some STIs don't need penetration at all. HSV-1, the cold sore virus, is now the most common cause of new genital herpes diagnoses in the UK, often passed on through oral sex.

Myth: "We are both monogamous, so we do not need to test"

If you both tested negative for all STIs before the relationship began, and neither of you has had other sexual contact since, there's no clinical need to retest. The catch is that many couples assume they're both clear without either of them ever having tested, and an infection from a previous partner can sit there quietly.

Testing together at the start of a new relationship removes the guesswork, and it's one of the kindest things you can do for each other.

Myth: "Condoms provide complete protection"

As above, condoms work best against infections carried in bodily fluids and protect only the skin they cover against herpes, syphilis and HPV. That's a reason to pair them with regular testing: condoms lower the chance of infection each time, and testing catches anything that gets through.

Myth: "STI testing is painful or embarrassing"

Most STI tests are a urine sample and a blood test, and that's it. If you have symptoms, a swab from the affected area takes seconds and causes very little discomfort.

You can walk in without an appointment, register under a different name and pay in cash. The consultation is private, it's quick, and nobody in the waiting room knows why you're there. We see thousands of patients a year for sexual health screening, so there's nothing unusual about looking after yourself.

Myth: "All STIs are curable"

Bacterial STIs (chlamydia, gonorrhoea and syphilis) are curable with antibiotics, though antibiotic-resistant gonorrhoea is a growing concern. UKHSA reported 13 ceftriaxone-resistant cases in 2024 and 14 in just the first five months of 2025, six of them extensively drug-resistant.

Viral STIs are managed rather than cured. HIV is controlled with lifelong antiretroviral therapy, which is highly effective and gives a near-normal life expectancy. Herpes comes back from time to time and is managed with antivirals. HPV often clears by itself but can persist and cause complications, and hepatitis B can become chronic.

Either way, early diagnosis prevents complications and onward spread, and with syphilis and HIV it's the difference between straightforward management and serious harm.

Myth: "You cannot get the same STI twice"

You can. Treatment for chlamydia, gonorrhoea, syphilis or trichomoniasis leaves no lasting immunity, so you can be reinfected as soon as you're exposed again. That's why partners need treating at the same time; otherwise reinfection is likely.

Viral STIs work differently. Herpes and HIV are lifelong, though manageable. You won't be "reinfected" with the same strain, but you can pick up a different type, for example HSV-2 when you already have HSV-1.

Myth: "Syphilis is a disease of the past"

In 2023, infectious syphilis diagnoses in England reached 9,513, the highest level since the 1940s. In 2024 early-stage syphilis rose a further 2% to 9,535 cases, and total diagnoses, including late-stage, reached 13,030. Recent rises have been relatively higher among heterosexual men and women than among gay and bisexual men, so it's spreading among people who may not think of themselves as at risk.

Caught early, syphilis is entirely curable with a single penicillin injection. We provide both testing and in-house treatment, including the benzathine penicillin injection on site.

Myth: "Home test kits are just as good as clinic testing"

Home kits have their place, especially for people who can't easily get to a clinic. They usually cover fewer infections (typically chlamydia, gonorrhoea, HIV and syphilis), and they leave out throat and rectal swabs, a physical examination and a doctor's consultation. Unclear or borderline results, which are more common with self-collected samples, mean a clinic visit anyway.

Come and see us if your home test was unclear, if you have symptoms, or if you want full testing with an examination and a doctor's advice.

What to test for, and how often

Why people choose us for STI testing

We're a private sexual health clinic at 117a Harley Street, established in 1984, with over 70,000 patients seen. Every package includes a consultation with a doctor (a £150 value, included), an examination if needed, prescriptions, and results within the stated times. Samples go to UKAS-accredited laboratory partners, the same accreditation standard NHS laboratories use.

We also treat syphilis in house with the benzathine penicillin injection, where most private clinics test and then refer you elsewhere for treatment.

We don't provide PrEP or PEP. If you need PEP after possible HIV exposure, go to your nearest NHS sexual health clinic or A&E within 72 hours.

References

1. UKHSA (2025). Sexually transmitted infections: annual data tables, England 2024.
2. BASHH (2024). UK National Guidelines for the Management of STIs.
3. Holmes, K.K. et al. (2004). Effectiveness of condoms in preventing sexually transmitted infections. Bulletin of the WHO, 82(6), 454-461.
4. NICE CKS (2024). Sexually transmitted infections - general approach.
5. BHIVA/BASHH/BIA (2020). UK National Guidelines for HIV Testing.