What are GnRH agonists?
Medications that cause the gonads (testes and/or ovaries) to stop producing sex hormones.
They're also known as Blockers, Hormone blockers, Goserelin, Zoladex, Triptorelin, Decapeptyl, Leuprorelin, Prostap, Buserelin, or Nafarelin.
What do GnRH agonists do?
- Facial hair
Prevents additional growth and may reduce and thin
- Body hair
Prevents additional growth and may reduce and thin
Weakens and makes smaller
- Head hair
Prevents some forms of hair loss
Causes temporary or permanent infertility
- Lower body
Causes genital shrinkage, reduces erections
Softens skin, reduces acne
Prevents change of body odour due to puberty
- Upper body
Prevents breast development due to puberty
Who can have GnRH agonists?
You need to have had persistent dysphoria, but there is no specific time frame
You must have capacity to consent for this treatment
If you have significant medical conditions, these need to be “reasonably well-controlled”
As of December 2020, under 16s may need a ‘best interests’ court order
Under 18s must be at Tanner Stage 2 or later; this may involve a physical exam
Under 18s must meet some requirements based on body mass index and bone density
How long do GnRH agonists last?
GnRH agonists are available in four week, twelve week and six month forms. Some are also available as a nasal spray taken daily. GnRH agonists usually take around two weeks to take full effect. Prolonged use may have some effects that are permanent and cannot be reversed.
How do I stay safe?
There are a number of health risks associated with hormone therapies. It’s important to get regular blood tests, both to spot problems before they arise and to make sure your dosage is correct.
Taking GnRH agonists without also taking a sex hormone (e.g. oestrogen and/or testosterone) or inadequate levels of sex hormones can cause osteoporosis or early heart disease 1.
Taking a sex hormone along with GnRH agonists will avoid the risk of osteoporosis or early heart disease. If GnRH agonists are being used without an additional sex hormone, DEXA (bone density) scans which measure bone mineral density may be needed 2, p.197.
GnRH agonists do not provide reliable contraception 3. They do not remove the risk of making someone pregnant, and they do not remove the risk of becoming pregnant.
Re-using needles puts you at risk of infection.
For any injected drug, it’s important to use sterile needles that are disposed of properly. If you are injecting yourself, you can find lots of safety information on our self-injection page.
If your injections are being done by a doctor or nurse, they should make sure the needles are sterile and dispose of them properly.
Who might want GnRH agonists?
NHS policy on treatment of under-16s has been affected by recent High Court rulings, and is subject to change. This page will be updated regularly.
If you have testes, treatment with GnRH agonists will reduce your testosterone levels. GnRH agonists will cause an initial rise in testosterone levels for the first few weeks of use, which is sometimes stopped by a short course of cyproterone 4, p.170.
If you have ovaries, treatment with GnRH agonists will reduce your oestrogen and progesterone levels. This will cause periods to stop, along with halting breast growth. Treatment with GnRH agonists is not normally necessary for people taking testosterone as testosterone normally adequately suppresses production of oestrogen.
If you do not have gonads (ovaries and/or testes), you will not need to take GnRH agonists. This means that after orchidectomy or salpingo-oophorectomy, there is no longer any need to use GnRH agonists.
If you are going through, or about to start puberty, GnRH agonists can be used to delay puberty. The effects of GnRH agonists when used in this way are considered a fully reversible treatment 5, and may reduce the distress of going through the “wrong” puberty 6 as well as the need for some other treatments later in life 7. This is generally considered safe, though there is some evidence that suppressing puberty may have a negative impact on bone development 6. Further information is available on the GIDS website.
Due to a recent high court ruling, under-16s will not receive this treatment from the NHS in England and Wales without a ‘best interests’ court order 8. The Tavistock and Portman NHS Foundation Trust is currently in the process of appealing this ruling, and a ruling on appeal will affect the whole of the UK.
If your doctor determines that prescribing blockers would be in your best interests, they will have to apply to a court for a final decision. At the moment, it is unclear exactly what this process will involve. It is likely that private clinics will adopt similar policies, but the legal situation is still developing, so it is difficult to say for certain whether this will become the norm.
Are there other options?
Alternatives to GnRH agonists include cyproterone, spironolactone, and anastrozole.
While these options are cheaper, GnRH agonists are generally preferred by NHS clinicians, as GnRH agonists are considered to have an excellent side-effect profile with minimal side-effects compared to the other alternatives 1, p.236.
How much will it cost?
Funding for GnRH treatment is available to people with testes who have a formal diagnosis on the NHS. It is also used by the NHS to prevent puberty in under 18s, and sometimes in conjunction with testosterone treatment to stop menstruation (periods) 9, p.5. Under-16s attending the GIDS clinic in England will require a ‘best interests’ court judgement to receive this treatment 8.
Under some circumstances, it may be possible to get hormone therapy from the NHS without a diagnosis.
You do not have to pay the full cost of medication you are prescribed on the NHS. You are not asked to pay anything at all in Northern Ireland, Scotland and Wales. In England, people are asked to pay a small charge for each item on their prescriptions. There are ways you can reduce or avoid this cost, which you can read about on the NHS website.
If you're receiving certain benefits, or are on a low income, you may be able to get help with the cost of travel for NHS treatment. Further information about help with travel costs can be found:
- on the NHS website
- on the Welsh Government website
- on the NHS Scotland website
- on the Northern Ireland government website
You can find detailed information about costs for hormone therapy from private gender services on our Private Fees page.
How do I use GnRH agonists?
Most GnRH agonists are injections. Usually you will be able to get a doctor or a nurse to perform the injection for you.
If you need to administer your injection yourself, Brighton Health and Wellbeing Centre have a video guide on how to do this for intramuscular injections like Triptorelin (Decapeptyl) or Leuprorelin (Prostap). Subcutaneous injections will require a different technique.
What kinds are there?
Commonly used GnRH agonists in the UK are Goserelin (Zoladex), Triptorelin (Decapeptyl) and Leuprorelin (Prostap). Certain clinicians also offer Buserelin (Suprecur/Suprefact) and Nafarelin (Synarel).
GnRH agonists are usually supplied as injections that are administered once every four weeks 10;11, twelve weeks 12;13;14, or six months 15.
Buserelin and Nafarelin are also available as a nasal spray that is administered twice daily 16;17;18; this could be a good option if you have difficulty with needles, but these are not normally prescribed on the NHS, and you will still need to have regular blood tests.
What else might I want?
GnRH agonists are often used in conjunction with a sex hormone like oestrogen or testosterone.
GnRH agonists may cause erectile dysfunction in people with penises. If this is not desired, it can be treated with sildenafil, tadalafil or vardenafil.
- 1.Seal, Leighton J (2017) “Hormone Treatment for Transgender Adults,” in Bouman, W. P. and Arcelus, J. (eds.), The Transgender Handbook: A Guide for Transgender People, Their Families and Professionals, Nova Science Publishers Inc, pp. 227–249. Link
- 2.Murjan, Sarah and T’Sjoen, Guy (2017) “Access to Clinical Services and the Role of Primary Care,” in Bouman, W. P. and Arcelus, J. (eds.), The Transgender Handbook: A Guide for Transgender People, Their Families and Professionals, Nova Science Publishers Inc, pp. 189–200. Link
- 3.FSRH Clinical Effectiveness Unit (2017) “Contraceptive Choices and Sexual Health for Transgender and Non-binary People.” Link
- 4.Seal, Leighton J (2007) “The practical management of hormonal treatment in adults with gender dysphoria,” in Barrett, J. (ed.), Transsexual and other disorders of gender identity: A practical guide to management, Radcliffe Publishing, pp. 157–190. Link
- 5.Hembree, Wylie C, Cohen-Kettenis, Peggy, Delemarre-Van De Waal, Henriette A, Gooren, Louis J, et al. (2009) “Endocrine treatment of transsexual persons: an Endocrine Society clinical practice guideline.” The Journal of Clinical Endocrinology & Metabolism, 94(9), pp. 3132–3154. Link
- 6.Giordano, Simona and Holm, Søren (2020) “Is puberty delaying treatment ‘experimental treatment’?” International Journal of Transgender Health, 21(2), pp. 113–121. Link
- 7.World Professional Association for Transgender Health (2011) Standards of Care for the Health of Transsexual, Transgender, and Gender Nonconforming People, 7th Version, WPATH. Link
- 8.NHS England (2020) Amendment to Gender Identity Development Service Specification for Children and Adolescents - December 2020, NHS England. Link
- 9.National Gender Identity Clinical Network for Scotland (2015) “Endocrine Management of Adult Transgender Patients.” Link
- 10.Electronic Medicines Compendium (2020) “Prostap SR DCS.” Link
- 11.Electronic Medicines Compendium (2017) “Zoladex 3.6mg.” Link
- 12.Electronic Medicines Compendium (2017) “Zoladex LA 10.8mg.” Link
- 13.Electronic Medicines Compendium (2020) “Prostap 3 DCS.” Link
- 14.Electronic Medicines Compendium (2017) “Decapeptyl SR 11.25mg.” Link
- 15.Electronic Medicines Compendium (2017) “Decapeptyl SR 22.5mg.” Link
- 16.Electronic Medicines Compendium (2019) “Suprecur 150 mcg Nasal Spray Solution.” Link
- 17.Electronic Medicines Compendium (2018) “Synarel Nasal Spray.” Link
- 18.GenderGP (n.d.) “Injection Alternatives: Prescribing nasal sprays as an alternative to injectable hormone blockers.” Link (Accessed 23rd November 2020)
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