Thousands of adults wanting gender reassignment are having to wait at least eight months for an initial appointment, ITV News has learned.
Many have to wait much longer, something which can force them to seek treatment outside the NHS.
One patient ITV News spoke to said they bought hormones online after being told they might have to wait two years for an initial appointment. Figures released under Freedom of Information laws show there are currently 3,888 adults waiting for their first appointment and 157 under 18s.
The average waiting time for an initial appointment is 34 weeks, but one adult clinic operates a 66-week waiting time and one children's unit has a 16-week wait. There are eight NHS clinics in England and none in Wales.
The NHS said it is trying to reduce waiting times and that extra funding is being put into gender reassignment programmes.
On average, the whole process costs £19,236 per patient - £29,975 for female to male, £13,867 for male to female.
In 2014/15, the total cost to the NHS in England was £17.1 million and £22.7 million has been budgeted for 2015/16.
Will Huxter, Chair of NHS England's Gender Identity Task and Finish Group, said: "The NHS has put additional funding into gender reassignment services for the last two years and will continue to do so.
"We recognise the urgent need to bring down waiting times, and to this end we are reviewing the findings from NHS England’s visits to gender identity clinics to inform recommendations for change and improvement.”
According to the figures obtained by ITV News, the average waiting time between first and second appointments varies enormously, with some people seen immediately and others waiting three to seven months. The wait between the first appointment and a referral for hormone treatment also varies hugely, from four to 37 weeks.
Our investigation also found:
- Clinics general do not record whether adults and children are experiencing mental health problems like depression while waiting
- Some clinics reported GPs refusing to prescribe hypo blockers on "ethical" grounds
- The Tavistock, the main children's clinic, is receiving 100 referrals a month
- The number of sessions required before physical intervention (hormone treatment) is prescribed varies between one and six
On average, there are twice as many patients waiting for a male to female reassignment than female to male.
Last year there were 330 planned surgical procedures, a number which is expected to increase this year.
The NHS said that surgery providers are being funded to operate at capacity and given extra money to recruit and train more staff. It added that not all patients undergo surgery.