Young teenagers are already treated in some countries
Young teenagers with serious gender identity disorders should be given drugs which will block puberty, international experts suggest.
The US Endocrine Society's draft guidelines say the move would give adolescents crucial time to decide which gender they want to live in.
New Scientist reports they are based work at a Netherlands clinic where 70 teens were successfully treated.
However, such treatments are currently not permitted for under-16s in the UK.
The guidelines state: "We recommend that adolescents who fulfil eligibility and readiness criteria for gender reassignment initially undergo treatment to suppress pubertal development."
The youngest patient treated by Dutch medics at the Leiden University Medical Clinic was 11, but most are 12 or over.
Henriette Delemarre-van de Waal, who helped treat the teenagers, said: "We don't have any patient who has regretted their decision on the treatment."
She added that many teenage patients with gender identity disorder find it hard to cope.
"They self-harm, they develop an enormous aversion to their bodies, they isolate themselves and their school performance suffers."
Clinics in other countries, including Canada, Australia, Germany and the US have also started offering the treatment.
Doctors recommend teenagers should not be treated until they have experienced the earliest signs of adolescence, where female breasts have begun to bud and boys have experienced some genital development.
This is so that medics can evaluate their emotional response to the effects of puberty, which can help predict if they will persist in wanting to change their sex.
The effects of the drugs are reversible, so puberty would resume if a teenager stopped taking them, but there has been little research into their long-term effects.
But Dr Russell Viner of the Institute of Child Health says a fear persists that young people who are given the treatment could change their minds about the process later on.
"The real question is: if you intervene early in a young person who would otherwise change their mind, do you reinforce their gender identity disorder? Do you remove the chance for change?"
He added: "We recently had the case in the US of a transsexual man who chose to become pregnant, and that may not have been possible if they had had early intervention."
Bernard Reed. of the Gender Identity Research and Education Society (GIRES), welcomed the guidelines as "an excellent piece of work".
He said he hoped British doctors would now consider delaying puberty in teenagers with gender identity disorder.