Gender affirming hormone therapy

Key points about gender affirming hormone therapy (GAHT)

  • GAHT refers to the hormone therapy (oestrogen or testosterone) used by some transgender and non-binary people to help align their body with their gender.
  • Not all transgender people use or want to use GAHT.
  • GAHT can help improve wellbeing and reduce distress.
  • Learn more about gender affirming hormone therapy.
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Gender affirming hormone therapy (GAHT) refers to the hormone therapy used by some transgender and non-binary people to help align their body with their gender.

  • Hormone therapy (oestrogen or testosterone) can cause changes in the way your body looks and functions that may help to relieve distress (gender dysphoria) in people who feel like their body doesn't reflect their gender identity. 
  • Not all trans people experience distress, and not all trans people want GAHT, but for many trans people GAHT is a necessary and important part of healthcare.
  • Hormone therapy is only 1 option in gender affirming healthcare, which refers to medicines and therapies people use to affirm their gender. Other examples include voice therapy, hair removal and surgery.

Note: The word trans is used here as an umbrella term to describe a wide range of genders including non-binary genders. It's used to describe someone whose gender doesn't match what was assigned to them at birth. Read more about gender diversity. 

Oestrogen based GAHT (also called E-GAHT) consists of 2 types of medicines – a form of oestrogen and a medicine to block testosterone. Both are needed unless you've had surgical removal of your testicles (in which case a testosterone blocker isn't usually needed).

It can be used by trans women or non-binary people who were assigned male at birth.

Effects of E-GAHT

E-GAHT can lead to gradual changes over many months and years. There are some things it can't change (see below). Effects vary between individuals.

Effects of E-GAHT
  • *Breast growth
  • *Infertility (please discuss the option of storing sperm prior to starting E-GAHT)
  • *Shrinking of your testicles
  • Lower sex drive
  • Decreased erections
  • Skin softening
  • Body fat redistribution
  • Reduced muscle mass
  • Slower hair growth on body and face (but it doesn't stop completely)

*Breast growth, likely infertility and genital changes are permanent (they may not reverse if you stop taking E-GAHT)


E-GAHT does NOT change the following:

  • voice (your healthcare provider may be able to refer you for voice therapy)
  • bone structure
  • adams apple
  • hair growth does not stop completely (some people use laser hair removal).

Note: contraception should still be used if you're having sex which could result in pregnancy.

You may hear about people using progesterone as part of E-GAHT, but currently there's not enough evidence for the benefit of using this as part of GAHT, so it's not generally recommended.


Oestrogen is usually started at a low dose and gradually increased over the first year of therapy. There are 2 forms of oestrogen funded and available in Aotearoa New Zealand:

  • Tablets (Progynova)
  • Patches (eg, Estradot). Oestrogen patches have a lower risk of blood clots than tablets.

Oestrogen injections are not funded in Aotearoa New Zealand. There's no evidence that oestrogen injections are more effective than the tablets or patches, and they may carry more risk because they can lead to higher oestrogen levels. For this reason, they're not part of national medical guidelines.

Oestrogen can cause blood clots (unless you use patches), liver problems, raised cholesterol and breast cancer. Risks are higher if you smoke, are over 45 years of age or have a family history of certain health problems.

Testosterone blockers

In Aotearoa New Zealand spironolactone tablets or cyproterone tablets are commonly used. Some people may use an injected implant (goserelin).

  • Spironolactone works by blocking the effects of testosterone in the body, eg, by promoting breast growth and slowing down body hair. Spironolactone can change blood potassium levels so blood test monitoring is important especially if you have kidney problems. Read more about spironolactone.  
  • Cyproterone works by stopping the release of testosterone. Cyproterone can cause side effects including low mood, weight changes, problems with your liver and meningioma (a non-cancerous brain tumour), so you should discuss this with a medical professional and use the lowest effective dose. Read more about cyproterone

Examples of testosterone preparations

There are a few types of testosterone available for testosterone based GAHT (T-GAHT). It's usually given as an injection, but a patch and gel is available as well.

  • Depo-testosterone – an injection every 1 to 2 weeks (you can be taught to self-inject this)
  • Sustanon – an injection given every 3 weeks (you can be taught to self-inject this)
  • Reandron – an injection given every 3 months (this must be given by a healthcare provider)
  • Testosterone patches – these may cause skin irritation.
  • Testosterone gel – applied once daily, usually in the morning (Testogel is available from April 2024).

T-GAHT can be used by trans men or non-binary people who were assigned female at birth.

Effects of T-GAHT


Effects of T-GAHT
  • *Deeper voice
  • *Increased body hair growth (chest, back, arms, legs)
  • *Facial hair
  • *Hair loss at your temples with the possibility of becoming bald over time
  • *Genital changes (growth of the clitoris)
  • Vaginal dryness
  • Acne
  • Redistribution of body fat
  • Increased muscle mass and upper body strength
  • Increased sex drive
  • Mood changes
  • Usually your periods will stop

*These are permanent changes. They won't reverse if you stop taking testosterone.


  • Note: You could still become pregnant even if your periods have stopped. It's important to use contraception if you're having sex which could result in pregnancy because testosterone is harmful to a developing foetus. Read more about contraception below.
  • Anyone with a cervix should discuss cervical screening with their healthcare provider.

Yes, if you're sexually active and want to avoid pregnancy, you should use contraception if you're using oestrogen based GAHT or testosterone based GAHT. Gender affirming hormone therapy doesn't prevent pregnancy.

If you're using T-GAHT, contraception is especially important. If you become pregnant while taking T-GAHT, this is harmful to the baby. If you wish to become pregnant you should stop testosterone first and discuss this with your healthcare provider.

Some people have problems becoming pregnant after being on T-GAHT. It's not known if this is due to testosterone, or if they would have had fertility problems for another reason. If you need advice on planning a pregnancy, talk to your healthcare provider. T-GAHT doesn't usually affect the quality of your eggs.

Maintenance GAHT prescribing for adult transgender patients(external link) Goodfellow Unit, NZ, 2022
Primary care gender affirming hormone therapy initiation guidelines(external link) Rainbow, University of Otago, NZ, 2023 
Qtopia(external link) A national training initiative supporting Aotearoa's primary care workforce to build confidence in how we support our trans and non-binary patients 

Webinar: Adult transgender patient care

Rona Carroll and Jennifer Shields cover the latest in healthcare for Aotearoa's trans and non-binary community.

(Goodfellow Unit, NZ, 2023)

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Credits: Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Dr Rona Carroll, FRNZCGP, PGDip, Wellington

Last reviewed: