People are being hospitalised for sexual health conditions that are easily treatable in local clinics, experts have warned, with some council budgets being cut by up to two-thirds over 10 years.

A Guardian analysis of English council spending on sexual health services found national cuts of more than a third since 2013, despite a rise in consultations for sexually transmitted infections (STIs). English councils spent £9.58 a head on sexual health services – including STI testing and treatment, contraception, and advice – in 2022-23, compared with £14.41 in 2013-14, after taking inflation into account.

Every council area has had a real-terms spending cut since 2014-15. Almost every council area has recorded a rise in gonorrhoea cases since 2017, and in 71% of areas cases of syphilis have increased.

Nationally, the number of gonorrhoea and syphilis cases reached a record last year, with 146 gonorrhoea diagnoses per 100,000 people. That was up from 58 in 2013, while syphilis diagnoses increased from 6.4 to 15.4. Hospital figures show admissions for syphilis and chlamydia doubled between 2013-14 and 2022-23, while gonorrhoea admissions tripled.

Dr Claire Dewsnap, a genitourinary medicine (GUM) consultant in Sheffield and the outgoing president of the British Association for Sexual Health and HIV (BASHH), said: “The fact is that it is quite ineffective to be spending money on treating people who have had to be admitted to hospital because they’ve got gonorrhoea joint infections when they could have got into their service really cheaply and treated really quickly. And that goes the same for all of the things that we do.”

The cuts to services – which have disproportionately affected younger, poorer and black populations – are also affecting elderly people, she said.

“Over-60s are now more likely to be diagnosed with a late HIV infection and syphilis rates in those people is going up. The age at which people are presenting with syphilis and gonorrhoea is getting wider – while it used to be thought of as something that really only impacted the young, it’s a much wider age group now.

“But really, this is a story of inequality and how this is really affecting those people who don’t have power and autonomy to push their way into services, because there just isn’t the access there used to be.”

Advice, prevention and promotion services have had the largest cuts to funding, with net spending down 44% since councils were made responsible for public health in 2013. Meanwhile, STI testing and treatment fell by 33% and contraception spending fell by 30%.

Some local spending reductions may be down to improvements in services – for example STI tests that can be ordered online are cheaper than clinic-based appointments, and have improved access for some patients. However, Dewsnap said spending had largely been slashed thanks to efforts to reduce staff costs, which make up about 80% of service budgets.

The window between someone contracting an STI and all their sexual partners being treated is getting “longer and longer and longer”, she said, resulting in more infections being spread.

“Ten years ago we would contact trace every partner of someone with chlamydia. We just can’t do that any more,” she added.

She described gonorrhoea and syphilis as the “canary in the mine”, as they are more rapidly spread and cause more obvious symptoms and complications.

Data published by the UK Health Security Agency shows the number of consultations to sexual health services is at record levels. Close to 4.4m consultations were recorded in 2022, 21% above the 2018 level when data is first available.

Combining spending from lower and upper tier local authorities shows the areas with the largest reduction in spending on sexual health services are the London boroughs of Redbridge and Harrow (down by 68% and 58% respectively), and Bolton (down by 57%).

David Fothergill, the chair of the Local Government Association’s community wellbeing board, said: “Local sexual health services are grappling with unprecedented increases in demand whilst levels of funding have declined.

“The government’s public health grant received by councils has been reduced in real terms by £880m since 2015. This has resulted in a reduction in councils’ ability to spend on STI testing, contraception and treatment.

“Investment in sexual health services helps to prevent longer-term illness and unwanted pregnancies, reducing pressure on our NHS and improving the health of people across our communities.”

Dewsnap called for funding to be restored, but warned that such a large number of skilled medical staff had left that “even if we suddenly have a load of money come into the sector tomorrow, which is very unlikely, you cannot replace that workforce overnight”.