Long-Term Risks
Polycythemia (High Red Blood Cell Count)
The most common significant side effect of testosterone therapy.
| HCT Level | Risk | Action |
|---|---|---|
| < 50% | Normal | Routine monitoring |
| 50–54% | Moderate | Consider blood donation |
| > 54% | High | Reduce T dose or therapeutic phlebotomy |
Cardiovascular Effects
| Effect | Impact |
|---|---|
| Blood pressure | T can raise BP in some individuals |
| HDL cholesterol | T typically lowers HDL |
| LDL cholesterol | Variable effect |
| Heart attack risk | Not clearly elevated in trans men |
| Stroke risk | Low absolute risk |
Sleep Apnoea
Testosterone can worsen pre-existing sleep apnoea. If you have sleep apnoea, monitor symptoms.
Cancer Risk
| Cancer Type | Risk on T |
|---|---|
| Breast cancer | Risk decreases relative to cis women (T suppresses E2), but trans men retain breast tissue unless they have top surgery, and breast cancer has been documented. Regular chest checks still recommended. |
| Ovarian cancer | No clear increased risk |
| Uterine/endometrial | Current evidence suggests T does not increase risk and may be protective (endometrial atrophy), but a small number of cases have been documented. Unexplained vaginal bleeding on T warrants evaluation regardless of duration of therapy. |
| Prostate | N/A (no prostate in AFAB individuals) |
Bone Health
Testosterone is protective of bone density. Trans men on T have normal to above-normal bone density.