The NHS has updated its guidelines on puberty blockers for children so that they can now only be prescribed following a court order.
The change was made on Tuesday night after a landmark ruling from the High Court that under-16s can only take the controversial treatment if they understand the "long-term risks and consequences".
The High Court, in its judgment, said that this would be "highly unlikely" for most children and teenagers, and that a court order should be sought by clinics considering prescribing the drugs to those aged 16 or 17.
The NHS guidance has now been revised to state that "no-one under the age of 16 can now be referred for puberty blockers unless a court rules it is in the child's best interests".
The revision was welcomed by the Safe Schools Alliance, which said that policies "must now be revisited" in light of the court's ruling.
"It is an important safeguarding principle that children must be protected and that there are some things they are unable to consent to," it said.
"We hope that this judgement leads to a renewed focus on effectively safeguarding all children. Political ideology must never be allowed to override safeguarding in any of our institutions, particularly the NHS and Schools.
"We trust that this will now see the end to experimental use of puberty blockers on under-16s and under-18s without court oversight."
The court case was brought by Keira Bell, 23, who started a medical transition to become male at the age of 16 while a patient at Gids, the only NHS clinic for young gender dysphoric people in the UK.
She went on to experience regret and decided to live as female again but only after suffering irreversible effects from the treatment, including a deepening of her voice and the removal of her breasts in a double mastectomy.
The other claimant in the case, Mrs A, is the mother of a 15-year-old autistic girl who is on the waiting list for treatment at Gids.
The clinic is run by the Tavistock and Portman NHS Trust which following yesterday's ruling said it was immediately suspending new referrals for puberty blockers and cross-sex hormones for under-16s. It plans to appeal the judgment.