What effects does it have?

What is it?

Hormone with many effects including muscle strengthening, hair growth, and lowering voice pitch.

It's also known as T, Testogel, Sustanon, or Nebido.

How long does it last?

Many of the effects of testosterone are permanent and start within weeks. Changes may take several years to reach their full effect.

More information


Testosterone use can cause serious medical conditions including polycythaemia (too many red blood cells which can increase stroke risk) and liver problems 1. For these reasons, it is important to only use testosterone under medical supervision with regular blood testing.


Testosterone may cause infertility which may be permanent. You should consider whether you need to use gamete storage (egg storage).


Some brands of testosterone contain peanut oil. Take care to read the ingredients in your medicine if you are allergic to peanuts.


Testosterone usually causes periods to stop, but does not remove the risk of pregnancy 2. Do not use testosterone as a method of contraception 3.


Testosterone does not remove the need for cervical screening tests.


Testosterone increases the risk of obstructive sleep apnoea (stopping breathing during sleep) which can lead to heart problems or sudden death.

Symptoms of sleep apnoea include:

  • very loud snoring
  • noisy and laboured breathing while you are asleep
  • stopping breathing followed by gasping or snorting

If you experience any of these symptoms, or you feel constantly tired or fall asleep during the day, speak to your GP. If you normally sleep in a room with someone else, you may wish to tell them the symptoms of sleep apnoea as you will not be awake to observe them.

Testosterone is commonly available as depot injections or as gels applied to the skin 1. Oral (pill) forms of testosterone are rarely used as blood testing is more complex, and patches (transdermal testosterone) are rarely used in the UK (partly because of the frequency of bad reactions to patches) 4.

In a small proportion of people menstruation (periods) is not stopped by testosterone therapy, and either GnRH agonists 5 or progesterone 6 can be used to do this instead.

Testosterone has noticeable effects on mood and thinking, and can increase energy and aggression, but can also help some people feel “more settled” in their body 1.

Testosterone may also cause acne. You can read more about acne and how to reduce it on the NHS Choices website.

Testosterone suppresses menstruation (periods). Some medical professionals have theorised that this could lead to endometrial hyperplasia (thickening of the lining of the womb), which might increase the risk of cancer. However, most studies have indicated that endometrial hyperplasia either does not occur, or happens only in a small minority of people, and that the risk of endometrial cancer is low with only one known case 1.

To avoid any risk from endometrial hyperplasia, current UK guidelines recommend that people taking testosterone long-term should have a hysterectomy, usually within a maximum of 4-5 years after starting testosterone 4. However, this surgery is optional and you may feel the risks involved in a major operation are unnecessary considering the extremely small probability of cancer. If you decide not to undergo hysterectomy it is recommended to have scans to check for thickening of the endometrium every two years to reduce this risk 1.

For testosterone therapy to begin, it is required that any other significant medical or mental health issues are “reasonably well controlled” 4. This means that a medical professional is currently helping or has helped you manage the condition.

Costs and funding

If you have received a formal diagnosis, the NHS will normally provide testosterone therapy. Testosterone therapy is not usually provided to under-18s on the NHS, with the effects of hormones during puberty being stopped by GnRH agonists until the age of 18 when testosterone therapy can be commenced. Some services may additionally provide testosterone to selected 16 and 17 year old people 7.

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 are using private gender services, the service will normally ask your GP to write you NHS prescriptions. Your GP may or may not agree to do this - it is up to them. NHS England have published guidance for GPs to help them make this decision, which you may wish to give to your GP. If your GP agrees to prescribe, the cost of your medication is the same as any other NHS prescription. If your GP does not, the private service can write you private prescriptions, which you will have to pay the full cost of.


  1. 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.
  2. 2 FSRH Clinical Effectiveness Unit (2017) “Contraceptive Choices and Sexual Health for Transgender and Non-binary People.” [online] Available from: https://www.fsrh.org/documents/fsrh-ceu-statement-contraceptive-choices-and-sexual-health-for/contraceptive-choices-and-sexual-health-for-transgender-non-binary-people-oct-2017.pdf
  3. 3 De Roo, Chloe, Tilleman, Kelly and De Sutter, Petra (2017) “Fertility Options in Transgender People,” 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. 133–146.
  4. 4 Royal College of Psychiatrists (2013) “Good practice guidelines for the assessment and treatment of adults with gender dysphoria.” [online] Available from: https://www.rcpsych.ac.uk/docs/default-source/improving-care/better-mh-policy/college-reports/college-report-cr181.pdf
  5. 5 National Gender Identity Clinical Network for Scotland (2015) “Endocrine Management of Adult Transgender Patients.” [online] Available from: http://www.ngicns.scot.nhs.uk/wp-content/uploads/2015/07/NGICNS-Endocrine-Management-of-Adult-Transgender-Patients-v1.0.pdf
  6. 6 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.
  7. 7 NHS England Specialised Commissioning Team (2016) “Clinical Commissioning Policy: Prescribing of Cross-Sex Hormones as part of the Gender Identity Development Service for Children and Adolescents.” [online] Available from: https://www.england.nhs.uk/commissioning/wp-content/uploads/sites/12/2016/08/clinical-com-pol-16046p.pdf

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Page last updated: April 2018