Clinics across the UK are reporting lengthening waiting times for patients awaiting treatment for sexually transmitted diseases (STDs).
Staff at GUM clinics nationwide are struggling to reduce waiting lists
Reports suggest an increasing number of patients are receiving treatment for diseases such as syphilis, HIV and gonorrhoea.
This increase in demand slows the rate at which patients can be tested and receive treatment.
The average wait for treatment can be as long as five weeks in some cases.
Over the last year 26,000 people have visited the Whittall Street Genitourinary Medicine (GUM) clinic, in Birmingham, for treatment - a 40% rise over the past five years.
Dr Jonathan Ross, who heads the clinic, told BBC News Online: "The average wait for treatment is between four and five weeks, as compared to three or four days a few years ago.
"We are seeing more people with infections and more people are coming forward for treatment."
The clinic operates a fast-track 'triage' system for those who have symptoms which require urgent attention.
Under the system, patients speak to a nurse over the telephone who refers them for treatment within a day or two where necessary.
A similar system operates at the GUM clinic in Newcastle General Hospital, where the number of patients being seen leapt from 8,695 in 2001 to 10,598 in 2003.
The average wait for treatment is three weeks, although people seen under the fast-track system will be seen within one or two days.
To cope with high demand, patients are expected to telephone the clinic to receive results and there are not follow up appointments unless it is necessary.
Clinical Director Richard Pattman said: "We are doing everything possible to ensure that we don't bring back anyone unnecessarily as it would block the treatment of a new patient."
The GUM clinic in the Royal Liverpool University hospital has dealt with around 28,000 patients over the last year.
This figure dropped from the 36,000 in 2002 after an appointment system was introduced 18 months ago.
Prior to this the clinic operated as a walk-in clinic where patients were seen the same day, but demand forced the end of this approach.
Clinical Director Anura Alawattegama said: "After the appointment system was first adopted the waiting time was around five weeks, but this has since dropped to two weeks for women and one week for men.
"We don't know whether the drop in numbers is because people failing to come to us because of the appointment system.
"We had to stop the walk-in system because we were working around two hours beyond closing time to see everyone - we couldn't cope."
Mr Alawattegama, who has been a consultant for 20 years, added: "In the last few years we have seen an increase in the number of people with syphilis and chlamydia in particular, as well as gonorrhoea and HIV.
"Obviously the safe sex message is not getting across."