Is testosterone safe for teenage boys?

What the evidence says

Testosterone is a hormone that naturally rises during puberty. There are two very different situations where the question 'is it safe' comes up, and the answer is different for each.

If a teenage boy is thinking about taking testosterone boosters, supplements, or anabolic steroids to build muscle or improve sports performance, the answer is no, it is not safe. Doctors' groups warn that these products can cause serious side effects and never actually work the way sellers claim.

Taking testosterone this way, without a doctor, can shrink the testicles, cause breast tissue growth, raise aggression, and harm the liver and heart. It can also stop bones from growing normally, since testosterone signals the body to finish growing. In Canada, anabolic steroids are controlled substances, so having them without a prescription is illegal, not just risky.

The second situation is different: sometimes a doctor prescribes testosterone for a boy who has a real medical reason, like hypogonadism (testes not making enough hormone on their own) or very delayed puberty. In these cases, specialists carefully choose low starting doses and increase them slowly, closely watching growth, bone development, and blood counts, because even medical testosterone can speed up bone maturation and potentially shorten adult height if not monitored properly.

Even in the medical setting, testosterone therapy for teens is considered fairly specialized. It has not been formally approved for this age group by drug regulators anywhere, so it is used carefully and off-label, only by paediatric endocrinologists who track the boy's growth and hormone levels over time.

So the bottom line for a parent: testosterone taken on your own, from a supplement store or online, is not safe for a teenage boy. Testosterone prescribed and monitored by a specialist for a real medical condition can be a reasonable and helpful treatment, but it still needs careful supervision.