If you are in your late teens or early twenties and looking at growth hormone compounds, one thing matters before anything else, and it runs the opposite way to the marketing.
Raising growth hormone accelerates bone maturation. If your growth plates are still open, that can close them sooner. So the compound sold to make you bigger may, in the one dimension you cannot get back, make you shorter.
That is a mechanism and not a measured outcome, because nobody has run the trial. Which is the second point: essentially none of this has been studied in people who are still developing.
At what age do growth plates close?
Later than most people assume, and it varies enormously.
Typical ranges run from about 14 to 19 in females and 16 to 21 in males. Those are averages across populations, not a schedule your own body follows.
The only way to know your own status is imaging. A hand and wrist X-ray, or a knee X-ray, read by a radiologist or an endocrinologist. Nothing about how tall you are, whether you have stopped growing, or how old you feel tells you whether the plates are open.
Oestrogen is what drives fusion, in both sexes, which is why the timing tracks puberty rather than birthdays. The evidence for that is unusually clean: in two rare genetic conditions affecting oestrogen, the growth plates never fuse and slow growth continues into adulthood.
Can MK-677 make you taller, or shorter?
Growth hormone and IGF-1 do drive linear growth while plates are open. That much is real, and it is why the marketing sounds plausible.
The part that gets left out is that the same signalling also advances skeletal maturation. Push it and the plates move faster toward the point where they close.
This has been measured, not merely reasoned about.
A multicentre cohort study published in 2026 followed children receiving prescribed growth hormone for short stature and tracked their bone age against their actual age. Every one-unit rise in IGF-1 was associated with a higher risk of accelerated skeletal maturation, at a hazard ratio of 1.24, holding in both boys and girls and surviving adjustment for height and weight. Under a stricter definition of advancement the association was stronger.[^3]
The authors state the concern plainly: excessive or rapid elevations in IGF-1 may accelerate growth plate maturation and potentially shorten the duration of linear growth.
Two limits govern how far that carries.
It is in children on prescribed growth hormone, monitored, for diagnosed conditions. Not in healthy nineteen-year-olds taking a secretagogue bought online, which is a different population and a different way of raising IGF-1.
And it measures bone age advancing, not final height falling. Faster maturation shortens the window; whether that costs any individual centimetres depends on how much window they had.
So the position sits above a mechanism and below a finding about you. Raising IGF-1 accelerates skeletal maturation in the closest population anybody has studied. Nobody has run the equivalent study in healthy young adults.
If you are under 18 and worried about your height
Height concern at 15 or 16 is common, real, and something medicine takes seriously. There is a proper pathway for it, and it is more useful than anything sold online.
A doctor can order a bone age X-ray, which tells you how much growth window remains. An endocrinologist can test for the conditions that actually cause short stature, some of which are treatable, and growth hormone is an approved prescription treatment where it is genuinely indicated.
That route gives you an answer about your own body. A compound bought online gives you a mechanism that might work against you, in a body nobody has studied it in yet.
If you are under 18, none of this is written for you. The boring advice is the right one: talk to a doctor, get the X-ray, find out where you actually stand.
If seeing a doctor is not straightforward, which for plenty of people at that age it is not, a school nurse or a pharmacist is a reasonable first conversation. Neither can order the X-ray, and both can tell you how to get to somebody who can, and neither requires explaining yourself to a parent first.
What has been studied in people under 25
Trials of growth hormone secretagogues have enrolled older adults, people with growth hormone deficiency, and healthy adults. Our guide to the growth hormone peptides sets out what those found, including a trial in older adults stopped early on a safety signal.
No trial has evaluated these compounds in healthy people under 25 for the purposes they are sold for. Muscle, recovery, height and safety are all unexamined in this age group.
For BPC-157, TB-500 and most of the rest, no trial has evaluated them in anyone under any conditions. Our guide on why most peptides have no human evidence covers how that happens.
One gap is more specific than the rest. Puberty and the years after it involve a hormonal system that is still settling. What an exogenous signal does to a system in that state, over years, is not a question anybody has asked, and it is a different question from what it does to a fifty-year-old.
Are SARMs the same as peptides?
MK-677 is sold in the same shops, on the same forums and in the same stacks as ostarine, RAD-140 and the rest of the SARMs. This audience mostly buys them together, and the risks attached to each are quite different.
SARMs act on the androgen receptor. Growth hormone secretagogues do not. That difference matters more at your age than at any other, because androgen-receptor compounds suppress your own testosterone production, and yours is at or near its lifetime peak.
Suppression in a young man with a healthy axis is a different proposition from suppression at forty. Recovery afterwards is variable and not guaranteed to be complete. The people it goes badly for tend to be those who ran several compounds for a long time before noticing anything.
And SARMs carry a documented liver signal. Case reports of drug-induced liver injury in young men taking them are in the medical literature, which is more than exists for most compounds in this category.
None of that is the subject here, and it belongs on the page because the two categories arrive together and get discussed as one. If you are looking at MK-677, you are probably looking at a SARM as well, and it is the SARM with the clearer risk attached.
Why peptides are marketed to this age group
Not a conspiracy, just where the attention is.
Physique and gym content skews young. The compounds are cheap relative to a gym membership, they are bought online without any gatekeeping, and the marketing promises exactly what a nineteen-year-old wants: faster results than training alone produces.
There is also a real thing underneath the pitch. Progress in the first two or three years of training is faster than it will ever be again, and it is easy to attribute that to whatever you happened to be taking at the time. Our guide on how long peptides take to work covers why that attribution is nearly impossible to make from personal experience.
Why this age has the least to gain
At twenty, your own growth hormone, testosterone and recovery capacity are at or near the highest they will ever be.
So this age group has the least to gain from these compounds and the most to lose from them. You are already running the physiology people spend money trying to get back.
The things that work at this age are the unglamorous ones, and they work better now than they will later. Consistent training with progressive load. Enough protein and enough total food. Sleep, which is where most of your growth hormone is released anyway, and which our guide on timing covers in detail.
At twenty, those three things return more than any compound will.
What to do if you have already started
Everything above reads as reasons not to, which is not much use if you began six months ago.
So the practical version. Stopping produces no withdrawal syndrome for any of these compounds, and no taper exists for any of them. Wanting to stop is sufficient reason to stop.
If the growth plate question still applies to you, meaning you are under about 21, a bone age X-ray answers it. That is worth doing whether or not you continue, because it tells you something about your own body that no amount of reading will.
If you have taken anything that suppresses testosterone, that is worth checking rather than guessing at. A blood panel covering testosterone, LH and FSH gives you an actual answer.
And if something has changed that concerns you, our guide on telling your doctor covers how to have that conversation, including the part about not being judged for it.
None of this requires a decision today, only a clearer picture of where you actually stand.
If your son, daughter or friend is taking this
The other way people arrive here is finding vials in a bedroom, or noticing a training partner's progress change abruptly.
The information is genuinely thin. Someone who has read the forums has a counterargument ready for every warning, and most of those counterarguments are no worse supported than the warnings.
What holds up better is the specific thing this page opened with. Raising growth hormone can bring growth plate closure forward, and if the person is still growing that is a cost they cannot get back. That is a mechanism they can check rather than a claim they can dismiss.
The X-ray is also a genuinely useful offer, because it answers a question they probably want answered anyway.
Where this stops being useful
Whether your own growth plates are open, which only imaging can tell you.
Whether any specific compound would affect your development, which nobody has measured for any of them.
Anything about a diagnosed growth condition, which is a matter for an endocrinologist and where approved treatments exist.
Common questions
Can MK-677 make you taller?
Only if your growth plates are still open, and there is a real chance it does the opposite. Raising growth hormone advances skeletal maturation, which can bring closure forward and shorten the window you have left. No trial has tested this.
At what age do growth plates close?
Roughly 14 to 19 in females and 16 to 21 in males, with wide variation. Only a bone age X-ray tells you your own status.
Is it safe to take peptides at 19?
Nobody knows, because no trial has enrolled healthy people under 25 for any of the purposes these are sold for. That is an absence of evidence, not evidence of harm, and at this age the potential gain is smaller than at any other.
I am 16 and short for my age. What should I do?
See a doctor and ask about a bone age X-ray. Short stature has causes worth identifying, some of them treatable, and growth hormone is an approved treatment where it is indicated. That route answers a question about your body instead of guessing at it.
Do peptides work better when you are young?
No trial has compared age groups. What is established is that your own hormonal environment is at its peak in your early twenties, which is an argument for the compounds mattering less, not more.
Will BPC-157 affect my development?
Nobody has studied it in anyone, at any age, in a controlled trial. That includes developing bodies, which is a more specific unknown than the general one.
Are SARMs the same as peptides?
No. SARMs act on the androgen receptor and suppress your own testosterone. Growth hormone secretagogues do not. They are sold together and they are different problems, and case reports of liver injury in young men taking SARMs are in the medical literature.
I have been taking it for six months. What now?
Stopping needs no taper, since none of these produce a withdrawal syndrome. If you are under about 21, a bone age X-ray answers the growth plate question. If you have taken anything that suppresses testosterone, a blood panel gives you a real answer instead of a guess.
My son or friend is taking this. What do I say?
A confident argument in either direction will not hold, because the evidence is thin on both sides. The point that survives is the growth plate one, which is a mechanism they can check, and offering to arrange an X-ray is more useful than a warning.
Is my rapid progress from the compound or the training?
Almost certainly the training, if you are in your first two or three years. That period produces faster progress than any later one, and personal experience cannot separate the two.
Sources
[^1]: Growth plate closure timing and assessment. Reported consistently across clinical and secondary sources. Epiphyseal fusion typically occurs between approximately 14 and 19 years in females and 16 and 21 years in males, with substantial individual variation. Radiographic assessment of the hand and wrist or knee is the only reliable method of determining an individual's status. A clinical reference or paediatric endocrinology source should be cited directly before publication, since the age ranges are load-bearing for this page.
[^2]: Role of oestrogen in epiphyseal fusion. Reported in the growth plate literature. Growth plate closure coincides with sexual maturation, with oestrogen playing a pivotal role in both sexes. In two genetic conditions affecting oestrogen, one in the oestrogen receptor gene and one in CYP19, the growth plate fails to fuse and slow growth continues into adulthood. See for example the discussion in a computed microtomography study of epiphyseal growth plate fusion, PMC5798587, read via search result. A primary endocrinology reference should be substituted.
[^3]: Ahn J, Jeong H, Suh J, Chae HW. Elevated IGF-1 levels are associated with accelerated bone age advancement during growth hormone therapy in children: a multicenter cohort study. Frontiers in Endocrinology, 2026. doi:10.3389/fendo.2026.1843625. PMID 42687935. *Peer-reviewed multicentre cohort study, abstract and results read at source. Children receiving growth hormone therapy for isolated growth hormone deficiency, idiopathic short stature, or born small for gestational age. Each one-unit increase in IGF-1 standard deviation score was associated with an increased risk of bone age advancement, hazard ratio 1.24, 95% CI 1.15 to 1.33, p<0.001, consistent in males and females and retained after adjustment for height and weight SDS. Under the stricter criterion of bone age to chronological age above 1.2, hazard ratio 1.46, 95% CI 1.23 to 1.72, p<0.0001. Risk was higher in idiopathic short stature (1.63) and highest in children born small for gestational age (2.15). The paper states that excessive or rapid elevations in IGF-1 may accelerate growth plate maturation and potentially shorten the duration of linear growth, and discusses accelerated growth plate senescence as a possible mechanism. Two limitations are stated in the body text and matter: the population is children on prescribed and monitored growth hormone for diagnosed conditions, not healthy young adults using secretagogues, and the outcome measured is bone age advancement rather than final adult height.
[^4]: Absence of trials in people under 25. See our guide to the growth hormone peptides, which carries the primary citations for the trials that do exist, in older adults and in growth hormone deficiency. A documented search of ClinicalTrials.gov and PubMed for interventional trials of growth hormone secretagogues in healthy participants under 25 should be run and recorded here before publication, since the central claim of this page is a negative.