Cuts are taking hold in the sexual health sector as in so many others. This year, for the first time in their recent history, sexual health organisations like FPA and Brook — the two biggest players in the field — have no core funding from the Department of Health.

Money from local authorities — themselves the victims of huge cuts — and charitable trusts, which have lower returns on their investments and higher demand for their remaining resources, has become increasingly hard to access. "Charities delivering sexual health services are seeing an assault from all areas," says FPA's chief executive, Julie Bentley.

When cuts to services of all sorts are coming thick and fast, a persuasive, vocal user lobby is key to fighting your corner. The trouble with sexual health services — and those for young people particularly, campaigners point out, is that they're not the kind of thing people want to shout about. Who's going to complain that they can't get tested for herpes?

Vulnerable, hard-to-reach teenagers are even less likely to stand up and complain. Yet it is those groups who are probably losing most as cuts to sexual health services start to take hold. While clinical services generally continue, targeted projects to groups such as young people at risk of being sexually exploited, or those with learning disabilities, doing "softer" work like helping with confidence and skills, are going.

FPA has lost a project run with Centrepoint for young homeless people who were sexually vulnerable; Brook reports funding for education work and some of its work with boys and young men being ended.

And sex education for all is suffering, they say, at a point when the coalition has already refused to make sex and relationships education (SRE) a statutory part of the school curriculum. FPA's award-winning parenting support programme, Speakeasy, is no longer getting funding from the Department For Education in England, while in Scotland its Big Lottery funding has ended.

Over ten years Speakeasy trained more than 10,000 parents and carers to talk to their children about sex and relationships. Several staff have been made redundant as a result of the cuts. "We're still delivering it but have had to massively scale it back," says Bentley. "It's a huge shame, because working with parents has a great impact."

Valuable infrastructure within local authorities has also been lost, says Brook's chief executive, Simon Blake, with advisers on PSHE and the healthy schools agenda disappearing. Last year a Guardian investigation found that teenage pregnancy co-ordinators — who bring together the work of local authorities, primary care trusts (PCTs) and voluntary sector services – had been cut in over a third of areas, including several where conception rates among under-18s are very high.

"There may still be people but they're very thin on the ground so they're not able to provide that kind of intensive support that makes a difference," Blake says.

Schools can now commission SRE services directly, rather than via their local authority, and Brook has found that fewer are doing so.

It's concerned that the increased autonomy on curriculum afforded to academies and free schools will add to that effect.

Blake believes swingeing cuts across the country to youth work provision, where a lot of SRE takes place, will also have an impact.

Bentley fears educational work historically delivered by clinical services will be chipped away as funding shrinks to cover only core work.

In a statement, a Department of Health spokesperson said "NHS organisations should not interpret efficiency savings as budget and service cuts", adding: "Primary care trusts should ensure that in each case the clinical needs of each person are taken into account and they should not be rationing access to treatment.

"Both the FPA and Brook have been contracted by DH for a number of years to provide national sexual health information services. The DH is currently considering responses following a tender for a new specialist sexual health information service. Both FPA and Brook were able to submit proposals for this tender. DH is also tendering for a new contact for helpline services which will include sexual health."

But FPA is also getting evidence that services such as advice on contraception and pregnancy are beginning to limit the age range they cover. "Young people" has normally meant focused on those aged 25 and under. "But now we're getting calls to our helpline from 21-year-olds saying 'I can't seem to find a service — all the ones in my area say they're only working with people aged 19 and under'," Bentley says.

She worries that when the new NHS commissioning structures come into action, the lack of young people likely to come forward to stress the need for access to full sexual health services means some may end up offering reduced hours or fewer elements.

The risks arising from all this are serious, campaigners say: saving money on education now is only likely to cost more down the line. A hard won decrease in English teenage pregnancy rates — which nonetheless remain the highest in western Europe — may be at stake.

"We do have the lowest teenage pregnancy rates for 40 years but they're not going to magically stay there," says Blake.

"Without that education and people feeling confident around sex and accessing contraception, you're just leaving people without the knowledge to take control of their sexual health ... you're going backwards very quickly to a point at which people didn't know what contraception was or how to access it. That's a really dangerous place to go to."

And the majority of cuts are still to come, he warns. Bentley agrees: "My fear is this is the tip of the iceberg."