Clinics are struggling to cope with an increase in sexually transmitted infections, a health expert has warned.
Diagnosis of syphilis in Wales rose by 53% from 2016 to 2017, while cases of gonorrhoea went up 21%, according to Public Health Wales' latest figures.
Dr Olwen Williams, president of the British Association of Sexual Health and HIV, blamed dating apps and said Welsh services needed more money.
The Welsh Government said it will fund a number of sexual health projects.
Dr Williams said: "We're seeing a genuine rise in STIs, if we were just seeing an increase in testing then our figures would look slightly different, but it feels that way.
"Certainly in my career I've never seen so much gonorrhoea or syphilis in my area, ever."
Dr Williams, who works for Betsi Cadwaladr University Health Board in north Wales, said a change in dating culture over the past few years, such as the use of dating apps, has had a knock-on effect on services: "What we can say about sexual mixing and sexual networking is that things have changed considerably.
"The frequency of app hook-ups and dating apps used as a sort of medium to access sexual activity seems to have increased significantly."
Usually if someone has contracted an STI, clinicians try to notify past partners so that they can get tested and treated as well.
However, the anonymous nature of some hook-up apps means clinicians are now unable to notify partners and reduce the spread of STIs, according to Dr Williams.
What is Syphilis?
- A bacterial infection which is normally spread through sexual intercourse
- It can be treated through a short course of antibiotics
- It is possible to catch syphilis more than once
- Symptoms include small sores on the genitals, a red rash on the palms of the hands or the soles of the feet
- It can spread to the brain and cause serious lasting problems if left untreated
What is gonorrhoea?
- The infection is spread by unprotected vaginal, oral and anal sex
- Symptoms can include a thick green or yellow discharge from sexual organs, pain when urinating and bleeding between periods
- However, vaginal and rectal infections often have no symptoms
- An untreated infection can lead to infertility, pelvic inflammatory disease and can be passed on to a child during pregnancy.
For more information visit NHS Direct.
Between 2011 and 2016, the number of people attending sexual health clinics in Wales doubled, from 86,000 to 176,000, according to Public Health Wales.
Despite the increasing demand on services, Dr Williams said there had been no significant investment in sexual health services from the Welsh Government during the past five years.
"Our biggest issue is around our staffing because we really do struggle to do outreach, to actually do partner notification... and if we're not doing that then all we'll do is see an increase in STIs in Wales," she added.
"I think services will struggle if we don't get investment."
Dr Williams also called for the introduction of online test kits that can be ordered on the internet and returned via the post - a recommendation backed by Public Health Wales' recent Sexual Health Review.
"If you go to England and Scotland, people can go on the internet and get a free test for chlamydia and gonorrhoea and a free HIV test, which is obviously very convenient and can be done in the comfort of your own home, whereas in Wales, at the moment, the majority of people have to come in to clinics to get tested," she said.
The Welsh Government said it had recently "commissioned an independent review of sexual health services in Wales" and was currently "implementing the review's recommendations in full".
A spokesman said it had already approved funding for a number of projects including a "pilot online STI testing service which will provide information, risk assessment, provision of sexual health testing kits and referral to treatment where appropriate".
Wales Live is on BBC One Wales on Wednesday, 3 October at 22:35 BST