The use of masculinizing hormones (testosterone) in females is associated with a range of significant health risks across multiple organ systems—including increased risks of cardiovascular events, blood disorders, gynecological pathologies, cancer, and premature death. Many long-term consequences remain unknown. This page summarizes the key adverse outcomes and safety signals identified in the medical literature.

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Cardiovascular and Blood Risks

• Heart Attack (Myocardial Infarction): Studies report a significantly increased risk. One analysis found nearly fivefold increased odds of a heart attack compared to other women not on hormones (Alzahrani et al., 2019). Another large cohort study found a 3.7-fold higher incidence (Nota et al., 2019).

• Changes to Lipid Profile: Testosterone consistently raisesLDL cholesterol and triglycerides while significantly lowering HDL cholesterol. (In particular, high triglycerides and low HDL are associated with metabolic syndrome and diabetes.) These changes are sustained over the long term (Gosiker et al., 2024).

• Erythrocytosis (dangerously high red blood cell count): A well-established risk, occurring in 11% of individuals in one large study. The cumulative risk increases over time, reaching 38% at 10 years and 50% at 14 years. This condition thickens the blood, increasing the risk of blood clots, stroke, and heart attack (Madsen et al., 2021).

• Blood Clots: Evidence suggests an increased risk for Venous Thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism (van Zijverden et al., 2024; Yelehe et al., 2022).

• High Blood Pressure: Increased systolic blood pressure is a known effect (Banks et al., 2021).

• Atherosclerosis: Testosterone is associated with an increased risk of early-stage atherosclerosis (hardening of the arteries), a precursor to major cardiovascular events and which is likely to be asymptomatic (Allgayer et al., 2023).

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Gynecological and Reproductive Harms

• Ovarian Damage: Testosterone exposure leads to poorer ovarian follicle health and increased DNA damage in oocytes. This suggests adverse effects on the primordial follicle pool and reduced egg viability, impacting future fertility (Bailie et al., 2023).

• Uterine and Endometrial Pathology: Despite stopping periods, the uterine lining often remains active. Pathologies are common, including endometrial polyps, fibroids, and hyperplasia. A multicenter study found active endometrium in 69% of individuals on testosterone who underwent hysterectomy (Grimstad et al., 2019).

• Infertility: The therapy suppresses ovarian function, leading to infertility. These effects may not be reversible (Bailie et al., 2023; De Roo et al., 2025).

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Cancer Risks

• Endometrial Cancer: The presence of endometrial hyperplasia, a precursor to cancer, has been documented. A case of endometrial intraepithelial neoplasia was reported in a 32-year-old after four years of testosterone (O'Connor et al., 2022).

• Breast Cancer: Reports of breast cancer as an adverse drug reaction have been identified (Gomez-Lumbreras et al., 2024).

• Liver Cancer: A case of androgen-receptor-positive hepatocellular carcinoma (HCC) was documented in a 17-year-old after just 14 months of testosterone (Lin et al., 2020).

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Urogenital and Pelvic Issues

• Vaginal Atrophy: Testosterone induces vaginal atrophy, leading to dryness, irritation, and painful intercourse (Baldassarre et al., 2013; Tordoff et al., 2023).

• Prostatic Metaplasia: In one study, 100% of individuals on testosterone developed prostatic metaplasia in their vaginal tissue—the growth of prostate-like glands. The long-term cancer risk of this change is unknown (Xu et al., 2022).

• Pelvic Pain: A high prevalence of pelvic pain is reported, with 72% of survey respondents experiencing it after starting testosterone (Zwickl et al., 2023).

• Pelvic Floor Dysfunction: A study found 94% of individuals on testosterone had symptoms of pelvic floor dysfunction, including urinary and bowel issues (da Silva et al., 2024).

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Neurological and Psychiatric Risks

• Idiopathic Intracranial Hypertension: This condition, characterized by high pressure around the brain, was the most predominant serious neurological adverse event found in an analysis of the FDA's reporting system. It can cause severe headaches and vision loss (Gomez-Lumbreras et al., 2024).

• Psychiatric and Behavioral Risks: Reports include anxiety, depression, and suicidal ideation (Gomez-Lumbreras et al., 2024).

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Surgical Complications

• Vaginal Cuff Dehiscence: Testosterone use is associated with more than double the risk of the vaginal cuff tearing open after a hysterectomy, a serious surgical complication (Wong et al., 2025).

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Bone Health

• Reduced Bone Density: Females on testosterone who go on to have their ovaries removed (oophorectomy) can experience significant reductions in bone mineral density, with one study finding low bone density in 10.5% of a 10-year cohort (Sanna et al., 2024).

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Premature Death

• Overall Mortality: A large, multi-decade study found that females taking testosterone had an 80% increased overall mortality risk compared to other women, an increase primarily attributed to non-natural causes of death (de Blok et al., 2021).

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Learn more about “gender-affirming care.”

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