What does growth hormone do to a 17 year old boy's height, any negative side effects?

Might increase: But only if it has been shown that he is not making this important hormone. Growth in boys continues until age 21 and it is a good thing to remember that height is extremely variable. Small people tend to have small children so the most important factor is to see if there are any relatively small people in the family history. Genes are the most important factor.

Potential harm : Except for very unusual circumstances, most boys have fused growth plates by age 17 with no significant growth potential left. Taking hgh without a clinical indication places people at risk for possibly developing later life malignancy as hgh will raise igf-1 levels which have been implicated in breast, colon, and prostate cancer to name a few. Acromegaly distorts facial features and bone. & on.