Guinea Pigs

There have never been any long term studies about the effects of cross gender hormone therapy on us until now.

Largest Study to Date: Transgender Hormone Treatment Safe
Medscape Medical News
Kathleen Louden
July 02, 2014

CHICAGO — Cross-sex hormone treatment of transgender adults leads to very few long-term side effects, according to the authors of the largest study to date to examine this issue.

More than 2000 patients from 15 US and European centers participated in the retrospective study, called Comorbidity and Side Effects of Cross-Sex Hormone Treatment in Transsexual Subjects, and nearly 1600 received at least 1 year of follow-up, the authors reported.

"Our results are very reassuring," principal investigator Henk Asscheman, MD, PhD, who heads HAJAP, his clinical research company in Amsterdam, the Netherlands, told Medscape Medical News. "There are mostly minor side effects and no new [adverse events] observed in this large population."
They reported that,
The primary serious side effect, venous thromboembolism, occurred in 1% of persons undergoing male-to-female (MTF) transgender transition and was due to estrogen treatment.
[…]
After cross-sex hormone treatment, side effects in MTF subjects, other than venous thromboembolism, included weight gain, reported in 5 persons (0.5%). In addition, 4 MTF subjects (0.4%) had a myocardial infarction, and 1 (0.1%) experienced a stroke. Hypertension was also common in this group, Dr. Asscheman stated.

The FTM subjects most often had the following side effects: acne with local treatment (2.9%, n = 15), weight gain (0.4%; n = 2), muscle pain (0.4%; n = 2), and liver-enzyme abnormalities (0.4%; n = 2).

Diabetes was also high up on the list.

But also remember this study was only a yearlong study of those who were on cross gender hormone for about 5 years, what will happen in ten, twenty or thirty years on hormones is still unknown.

I have been on hormones for close to ten years.