http://www.ncbi.nlm.nih.gov/pubmed/18834347

“The systolic and diastolic blood pressures in FTM transsexuals treated with androgen were significantly higher than those in untreated FTM transsexuals…

Conclusions: Long-term and high-dose administration of androgen is likely to cause increased arterial stiffness in FTM transsexuals.”

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There is a honeymoon period when a person first transitions. The honeymoon is what many gender nonconforming teens see on YouTube. Information about long term health effects, and doubts about transition (expressed by FTMs themselves) is out there–but you have to hunt for it.