A review of the "safety and reversibility" of puberty blocker drugs is due to be released by the Ministry of Health in the coming months.
The drugs are prescribed to children and teenagers dealing with transgender issues, with supporters saying they can pause development while gender options are explored.
The Ministry told Newshub it is currently "examining whether or not puberty blockers can be considered safe and fully reversible".
The "evidence brief" is due back in the next 2-3 months.
The review comes as several countries exercise caution with puberty blockers, with the United Kingdom this month stopping the use of the drugs in most circumstances.
Before September last year the Ministry of Health said: "Puberty Blockers are a safe and fully reversible medicine that may be used from early puberty through to later adolescence to help ease distress and allow time to fully explore gender health options."
But in September the Ministry updated it, taking out the part that says "safe and fully reversible".
Now, the Ministry of Health has issued a new statement to Newshub for Paddy Gower Has Issues which said: "The Ministry of Health does not have formal guidelines on puberty blockers" and noted that any "medical treatment carries a balance of benefit and risk."
"Because individual circumstances vary considerably, decisions around the use of puberty blockers are best made by patients and their families in consultation with appropriate health professionals," the Ministry said.
The Ministry said it wanted to "ensure that any information we do publish about the safety and reversibility of puberty blockers is supported by the latest clinical evidence."
The use of puberty blocker drugs has really ramped up over the past 10 years. There were 137 patients back in 2012, and it's gone up every year since to 771 last year.
Auckland Pediatrician Doctor Rachel Johnson who is a member of PATHA (Professional Association of Transgender Health Aotearoa), said: "Puberty blockers are a medication that are used to pause puberty, they can't turn it backwards, so they can't reverse changes that have already happened but absolutely they can just pause things. So imagine if physical changes that cause stress are occurring, by stopping those can be incredibly beneficial on a psychological and physical level. But if you were to stop those puberty blockers, puberty would just kick in again."
"Over ten years of following people who are on blockers, with the worldwide evidence that is available, I do think that accessing puberty blockers in the context of the way young people can in New Zealand is really appropriate," Dr Johnson said.
"They're not some universal treatment for every trans youth, it's always a really carefully considered decision. Whether the benefits outweigh any potential risks."
Asked if they were safe and fully reversible, Dr Johnson replied: "I would absolutely say in the years of experience of using blockers and the worldwide evidence they are safe and reversible."
But overseas there isn't consensus on the evidence.
Earlier this month the United Kingdom put a stop to virtually all doctors being able to prescribe puberty blockers. Now children can only access them if they're part of clinical research.
The National Health Service England decision came after a high-profile legal case against gender clinic the Tavistock Centre by a 24-year-old woman who was given puberty blockers as a teenager but later regretted her transition.
There has also been a major independent review by respected pediatrician Hilary Cass which found 'gaps in the evidence' around the drugs
Dr Dylan Wilson, a pediatrician in Australia who has concerns about puberty blockers, said: "There's nothing that exists here in Australia or New Zealand to demonstrate more benefit than exists overseas. So the fact that the UK is now saying this can only be done as part of research demonstrates that. That research still needs to happen.
"Rather than allow them to explore. It does the opposite. It fixes them into a pathway that they find very hard to get out of because they don't have the ability to say, actually, this is wrong for me," he said.
Asked if this was not giving children enough credit that they really know themselves well, Dr Wilson said: "I still don't believe that a child who is precocious, articulate, hugely intelligent and is absolutely adamant convinced that they are who they say they are. I still don't feel like a child at the age of 12, 13, 14 even up to 16 [understands] the implications of what they are."
Newshub spoke to Dr Wilson because New Zealand doctors with similar views were worried about speaking out.
Dr Wilson said: "My main concerns from New Zealand is the lack of ability to express those concerns and have those concerns shut down and considered transphobic as a result. The lack of ability to discuss this as a medical issue is hugely concerning."
Full Ministry of Health statement on puberty blockers
"The Ministry of Health does not have formal guidelines on puberty blockers.
"Because individual circumstances vary considerably, decisions around the use of puberty blockers are best made by patients and their families in consultation with appropriate health professionals. It is important to note that any medical treatment carries a balance of benefit and risk that needs to be considered in context by the person in partnership with their health professional.
"The evidence brief, which is examining whether or not puberty blockers can be considered safe and fully reversible, is currently being examined. We expect the findings will be ready for release within the next 2-3 months.
"The evidence brief was undertaken to ensure that any information we do publish about the safety and reversibility of puberty blockers is supported by the latest clinical evidence."