What is HRT? (Trans Female Guide)

HRT stands for Hormone Replacement Therapy. For trans females, it is a medical treatment that helps align your physical characteristics with your gender identity through the use of hormones such as estrogen, testosterone blockers, and progesterone.

How HRT Works

Gender-affirming hormone therapy (GAHT) for trans women typically involves three steps:

1. Suppressing testosterone – Reducing your body's natural testosterone production to minimise masculine traits.
2. Introducing estrogen – Taking estradiol to promote feminine physical changes.
3. Introducing progesterone – Optionally added later to further support feminine development, particularly breast maturation.

Estradiol serves two important roles: it directly promotes feminine development, and at sufficient doses it can suppress testosterone on its own.

Progesterone is not strictly necessary, but some trans women find that adding it:

• Helps round out breast shape (Tanner stage 4/5 development)
• May improve libido, mood, and sleep quality
• May reduce anxiety

Evidence for progesterone's benefits is largely anecdotal; clinical studies are limited. Some people experience negative side effects including mood swings, depression, or weight gain. It is typically added after 6–12 months of estrogen therapy.

What HRT Does (and Doesn't) Do

Physical Changes

Timelines are highly individual

The ranges below are population-level observations, not predictions for any one person. Onset and progression depend heavily on your regimen, dosage, age, genetics, and overall health. The "typical plateau" column does not mean change stops at that point — many people continue to see changes beyond these timeframes, particularly with regimen adjustments. Do not use this table to judge your own progress.

Change	Typical Onset	Typical Plateau	Reversible?
Breast development	3–6 months	2–3 years*	No
Skin softening / decreased oiliness	3–6 months	Variable	Yes
Body fat redistribution (to hips/thighs)	3–6 months	2–5 years*	Yes (slowly)
Decreased muscle mass	3–6 months	1–2 years	Yes
Reduced body/facial hair growth	6–12 months	3+ years	Partially
Decreased libido / spontaneous erections	1–3 months	1–2 years	Yes
Decreased testicular volume	3–6 months	2–3 years	Partially
Scalp hair loss slowing/reversal	1–3 months	1–2 years	Partially

* Changes in diet, weight, exercise, or HRT regimen can continue to drive development beyond the typical plateau.

Fertility Warning

Feminising HRT will likely reduce your fertility, possibly permanently. HRT is not a contraceptive — use a reliable method of birth control if relevant to you.

Gamete Storage

If you are considering having biological children in the future, discuss sperm/gamete storage with a healthcare provider before starting HRT.

What HRT Does NOT Do

• Change your voice — Estrogen does not affect the vocal cords. Voice training or surgery is required.
• Remove facial or body hair — Estrogen slows hair growth but does not remove existing terminal hair. Laser hair removal or electrolysis is needed for permanent results.
• Guarantee fertility preservation — HRT significantly reduces sperm production; permanent infertility is possible.
• Shrink your Adam's apple — Estrogen does not affect cartilage. Surgical reduction (chondrolaryngoplasty) is the only option.

Key Hormone Targets & Monitoring

For feminising GAHT, the Endocrine Society and WPATH SOC8 recommend targeting:

• Testosterone (T) — below 50 ng/dL (< 1.73 nmol/L)
• Estradiol (E2) — in the cisgender female range, typically 100–200 pg/mL (367–734 pmol/L)

Achieving both targets simultaneously is not always possible. A Mount Sinai study of 1,195 trans feminine individuals found that:

• Nearly half (43%) of people with E2 below target (<100 pg/mL) still achieved T suppression below 50 ng/dL.
• 88.5% of those with E2 above 200 pg/mL achieved T suppression, but some still did not.

The Endocrine Society recommends monitoring hormone levels every 3 months during the first year of therapy, and adjusting doses accordingly.

Common Medications for Feminising HRT

Estrogen Options

Form	Examples	VTE Risk	Notes
Oral (pills)	Estradiol valerate, hemihydrate	Higher	2–8 mg/day; can be taken sublingually for better absorption
Transdermal (gel/patches)	Oestrogel, patches (50–100 mcg twice weekly)	Lower	Preferred by guidelines; steady absorption, less liver impact
Injections	Estradiol valerate (EV), cypionate (EC)	Lower	EV 2–4 mg starting, up to 8 mg maintenance (every 5 days); EC 1–5 mg every 7 days

Transdermal is preferred

Clinical guidelines recommend transdermal 17β-estradiol over oral formulations, particularly for individuals with elevated cardiovascular or clotting risk, due to its more favourable safety profile.

Anti-Androgen (Testosterone Blocker) Options

Medication	Mechanism	Typical Dose	Notes
Spironolactone	Blocks androgen receptors; mild T suppression	50–200 mg/day	Most common in US; monitor potassium levels, especially in those over 45
Bicalutamide	Competitively binds androgen receptors	25–50 mg/day	Does not lower T levels; blocks T from binding
Cyproterone Acetate (CPA)	Progestogen; suppresses T production	10–12.5 mg/day	Effective but associated with meningioma risk at higher doses — see warning below
GnRH Agonists	Suppresses pituitary gonadotropins	Injection every 12 weeks	Most effective method; expensive and not always accessible
Finasteride	5α-reductase inhibitor (blocks DHT conversion)	1–5 mg/day	Primarily for scalp hair preservation; not a full anti-androgen

Cyproterone Acetate (CPA) and Meningioma Risk

Higher cumulative doses of CPA are associated with a significantly increased risk of meningioma (a type of usually benign brain tumour), with the risk being dose- and duration-dependent. The risk increases particularly with long-term use at doses of 25 mg/day or higher. The current recommended dose for HRT has been lowered to 10–12.5 mg/day to reduce this risk.

Note: The European Medicines Agency (EMA) 2020 PRAC ruling formally restricts all medicines with daily CPA doses of 10 mg or more, meaning 12.5 mg/day is within the restricted range, not a safe ceiling below regulatory concern. Readers using 10–12.5 mg/day should understand this and discuss cumulative dose monitoring with a provider if possible. CPA is contraindicated in anyone with a history of meningioma.

On Finasteride

Finasteride is not a primary testosterone blocker for transfeminine HRT. It mainly reduces DHT (dihydrotestosterone), which helps with scalp hair preservation and can modestly slow body-hair progression. It is sometimes used alongside a primary anti-androgen.

Monotherapy (Estrogen Alone)

Using only estradiol (without an anti-androgen) is called monotherapy. High-dose injectable or transdermal estradiol can suppress testosterone to female range on its own for some individuals, making monotherapy viable in those cases.

Oral Monotherapy Warning

Do not attempt monotherapy with oral estrogen pills alone. Oral estrogen at doses high enough to suppress testosterone carries a significantly elevated risk of blood clots (VTE). Monotherapy is only appropriate with injectable or high-dose transdermal estradiol.

Side Effects & Risks

Venous Thromboembolism (VTE) — Blood Clots

The most serious known adverse effect of feminising hormone therapy is venous thromboembolism (VTE) — the formation of blood clots in veins.

• Oral estrogen increases VTE risk by producing procoagulant changes in the liver — including increased APC resistance and elevated clotting factors IX and XI — because it undergoes first-pass hepatic metabolism. ^[1]
• Transdermal estradiol does not undergo first-pass metabolism and is not associated with the same procoagulant changes, making it the lower-risk option. ^{[1], [2]}
• VTE risk is highest in the first year of hormone therapy and remains elevated thereafter. ^[1]
• Higher-risk groups include: people over 60, smokers, individuals with obesity, those with a personal or family history of VTE, and those with inherited clotting disorders (e.g. Factor V Leiden, antithrombin deficiency). ^[2]

Other Side Effects

• Blood pressure: Estrogen therapy has been associated with increases in systolic blood pressure in some studies, making routine cardiovascular monitoring important. The relationship is complex and not consistent across all studies. ^[3]
• Triglycerides: Oral estrogen in particular has been associated with increased triglyceride levels, which may contribute to cardiovascular risk. ^[4]
• Gallbladder disease: Estrogen appears to promote gallstone formation by increasing cholesterol saturation in bile. A large study of over 38,000 trans women found a significantly increased risk of gallbladder disease in those on estrogen GAHT. ^[5]
• Breast cancer: Trans women on hormone therapy have a higher risk of breast cancer than cisgender men, but a lower risk than cisgender women. The 2019 Dutch nationwide cohort study (n = 2,260) found the risk was roughly 47× higher than cisgender men, but more than 3× lower than cisgender women. ^[6]
• Elevated prolactin: Cyproterone acetate and higher estradiol exposure have been associated with elevated prolactin levels in some patients, which should be monitored periodically. ^[2]

Risk Mitigation

• Use transdermal estradiol if you have elevated cardiovascular or clotting risk — clinical guidelines strongly recommend this. ^{[1], [2]}
• Stop smoking — smoking independently raises VTE and cardiovascular risk, and the combination with oral estrogen is particularly concerning. ^[2]
• Maintain a healthy weight and stay physically active to reduce baseline cardiovascular and thrombotic risk.
• Monitor blood pressure and lipids regularly as recommended by your provider. ^[3]
• If taking spironolactone, have potassium checked every 3 months in the first year, then annually. Risk of clinically significant hyperkalemia is low in otherwise healthy individuals under 45, but increases with age. ^[7] Note: while the Hayes et al. (2022) study suggests routine monitoring may be unnecessary in those under 45 without risk factors, the Endocrine Society's official guidelines still recommend 3-monthly monitoring for all patients — this is emerging evidence challenging current protocol, not yet the standard.
• Before major surgery, discuss with your provider whether to temporarily pause oral estrogen — practices vary between clinicians and institutions. ^[1]

Is HRT Safe?

The Endocrine Society and other major medical organisations recognise gender-affirming hormone therapy as an evidence-based treatment for gender dysphoria when prescribed and monitored appropriately.

Research consistently demonstrates that GAHT is associated with improvements in psychological well-being, quality of life, and reductions in gender dysphoria. As with any long-term hormone therapy, ongoing monitoring is important to manage risk.

How Long Until Changes Are Complete?

Physical changes are typically fully apparent within 3–5 years. Individual results vary based on:

• Dosage and route of administration
• Age — younger individuals often see faster changes
• Genetics and overall health

DIY vs Prescribed HRT

Prescribed HRT

• Under supervision of an endocrinologist or knowledgeable provider
• Regular monitoring and dose adjustments
• Pros: safer, medically supervised; free or low-cost in many healthcare systems
• Cons: long waiting lists (up to 5–7 years in some countries), gatekeeping barriers, high costs in private systems

DIY HRT

• Obtaining medications directly without a prescription
• Pros: immediate access, full control over your care, often cheaper
• Cons: requires self-education and personal responsibility for sourcing and blood testing; no medical oversight

If you use DIY HRT, you must:

1. Test your blood regularly — at minimum every 3 months during the first year
2. Source from reputable vendors with verified product quality
3. Educate yourself thoroughly — understand dosing, side effects, and emergency warning signs

Is HRT Reversible?

Some effects are permanent or long-lasting:

• Breast development — permanent once breast tissue forms (may reduce slightly if HRT stops)
• Fertility changes — may be permanent even after stopping HRT
• Testicular atrophy — partially reversible but can be long-lasting

Most other changes reverse if HRT is stopped:

• Fat redistribution, skin softening, reduced muscle mass, and other hormonal effects generally reverse over time, though this can take months to years.

References

The following sources are cited in the Side Effects & Risks section.

1. Safer JD et al. (2019). Managing the risk of venous thromboembolism in transgender adults undergoing hormone therapy. Journal of Blood Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC6628137/

2. Patel N et al. (2024). Gender-affirming hormone therapy in the transgender patient: influence on thrombotic risk. PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC11665511/

3. Banks K, Kyinn M, Leemaqz SY et al. (2021). Blood pressure effects of gender-affirming hormone therapy in transgender and gender-diverse adults. Hypertension (AHA). https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.120.16839

4. Irwig MS. (2020). Cardiovascular health in transgender people. JCEM. https://academic.oup.com/jcem/article/105/3/e894/5658514

5. Collin L et al. (2024). Gallbladder disease in transgender individuals: associations with gender-affirming hormone therapy. International Journal of Transgender Health. https://www.tandfonline.com/doi/full/10.1080/26895269.2023.2283532

6. de Blok CJM et al. (2019). Breast cancer risk in transgender people receiving hormone treatment: nationwide cohort study in the Netherlands. BMJ. https://www.bmj.com/content/365/bmj.l1652

7. Hayes H, Russell R, Haugen A, Nagavally S, Sarvaideo J. (2022). The utility of monitoring potassium in transgender, gender diverse, and nonbinary individuals on spironolactone. Journal of the Endocrine Society. https://academic.oup.com/jes/article/6/11/bvac133/6696042