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Diagnoses of sexually transmitted infections (STIs) in England fell 8.3% in 2025, new data from the UK Health Security Agency (UKHSA) show — though rising syphilis rates in heterosexual women and growing antibiotic resistance are tempering the improvement.

The data, covering the period to the end of December, showed decreases in infectious syphilis diagnoses (13.5%), gonorrhoea (10.9%), chlamydia (10.3%), and first episode genital warts (7.3%).

The decline was a “cause for optimism,” the UKHSA said in a press release. However, it cautioned there had been an overall increase of 3.1% in genital herpes, and despite infectious syphilis diagnoses having fallen overall, diagnoses in heterosexual women had increased by 4.8%.

Almost half (45.2%) of all new STI diagnoses in 2025 were for chlamydia. The other commonest diagnoses were gonorrhoea (19.1%), first episode genital herpes (8.6%), and first episode genital warts (7.0%).

Gonorrhoea and Chlamydia Driving Reductions

The decline in STIs overall had been largely driven by reductions in commonly diagnosed infections, including gonorrhoea and chlamydia. 

There had been decreases in bacterial STI diagnoses amongst gay, bisexual, and other men who have sex with men between 2024 and 2025 — with decreases seen in gonorrhoea (5.9%), chlamydia (14.4%), and infectious syphilis (18.7%), the lowest level in that group since 2016. Decreases had also occurred in genital warts (8.3%) and genital herpes (1.5%).

Despite young people aged 15-24 years experiencing relatively high new STI diagnosis rates, compared to 2024, the number of diagnoses in 2025 in this group had decreased by 12.5%. This was largely due to decreases in chlamydia (12.8%) and in gonorrhoea (21.5%).

However, overall STI levels remained “high by historical standards,” the British Association for Sexual Health and HIV (BASHH) said, with diagnosis rates particularly so in young people aged 15-24 years, gay and bisexual men, and people living in deprived areas. 

Concerns Persist

Emerging challenges existed, however, including rising syphilis in women, antimicrobial resistance, and persistent inequalities, BASHH said.

Rising rates of syphilis amongst women who have sex with men, against a backdrop of overall decreasing rates, is a “real concern,” said Dr Cara Saxon, BASHH president, in a press release. “There is a gap in evidence around effective preventive interventions for women and syphilis that needs to be urgently addressed,” she said.

Although most bacterial STIs are easily treated with antibiotics, areas of concern persisted. Whilst overall gonorrhoea diagnoses had declined, cases of ceftriaxone-resistant gonorrhoea were increasing, with 29 cases reported in 2025 — more than double the number of cases reported in 2024.

Amongst young women aged 15-24, who are recommended to be screened through the National Chlamydia Screening Programme, there had been a 9.4% decrease in the number of chlamydia tests carried out.

“The decline in chlamydia screening is a concern,” said Dr Hamish Mohammed, consultant epidemiologist at UKHSA, in a press release.

Implementation Essential

Sexual health services began offering doxyPEP last year — a course of doxycycline offered to people at increased risk of syphilis. The world’s first national vaccination programme to protect against gonorrhoea was also rolled out by the NHS last year, with evidence suggesting the 4CMenB vaccine may offer 30%-40% protection against gonorrhoea.

Although the impact of these services is still being evaluated, some of the decline in STI diagnoses seen amongst gay and bisexual men in 2025 may reflect the impact of these interventions, the UKHSA suggested.

“We have more tools than ever to prevent STI transmission, including vaccines, HIV PrEP and doxyPEP to prevent syphilis,” said Saxon. “The challenge now is not just innovation, but implementation — ensuring services have the capacity, clarity and resource to deliver these interventions safely, appropriately, and at scale,” she added.

Rob Hicks is a retired National Health Service doctor. A well-known TV and radio broadcaster, he has written several books and has regularly contributed to national newspapers, magazines, and online publications. He is based in the United Kingdom.