Possible Side Effects/Risks of Feminizing Hormones

The medical effects and safety of “feminizing” hormones are not fully understood. Most of the studies on the medications used by MTFs as part of hormone therapy involve non-trans people using different doses than MTFs usually use. There may be long-term risks that are not yet known.

Many of the known risks of “feminizing” hormones can be reduced by creating a hormone combination that is tailored to your specific situation. Prevention includes periodic blood tests to keep an eye on potentially risky conditions, and minimizing other health risks. Stopping smoking is the number one thing you can do to reduce your risk of blood clots and heart disease (and also make it possible to increase the amount of estrogen that can safely be prescribed).

General risks

The medications taken in hormone therapy are processed by the liver.There is a possibility that taking hormones over a long period of time can put strain on the liver, possibly leading to liver disease. It is generally recommended that MTFs taking feminizing hormone therapy get their liver enzyme levels checked periodically to monitor liver health. This is especially important if you have Hepatitis B or C, are a heavy drinker, or are otherwise at risk for liver disease.

Being visibly trans in a transphobic society has social risks. While it is possible to stay closeted if you’re taking small doses of anti-androgens (as the changes aren’t highly visible), estrogen causes changes that can be visible, including breast growth. Some visibly trans people experience violence, harassment, and discrimination, while others have lost support of loved ones. If you are worried or stressed about these possibilities, or unsure of how to tell a loved one that you are thinking about taking or planning to take hormones, peer and/or professional counselling can be useful.


Side effects/risks of estrogen

Taking estrogen increases the risk of blood clots. Blood clots can cause death, permanent lung damage (clot in the lungs), permanent brain damage (stroke), heart attack, or chronic problems with the veins in your legs. The risk of blood clots is much higher for smokers, especially those who are age 40 or higher. The danger is so high that some doctors will not prescribe estrogen if you are a smoker; most will only prescribe you a low dose as long as you are still smoking. The risk of blood clots may be reduced by taking estrogen via skin patch, cream, or gel (rather than pill/injection) and also by using a lower dose of estrogen.

Taking estrogen changes the way your body metabolizes and stores fat.Taking estrogen can increase deposits of fat around your internal organs, which is associated with increased risk for diabetes and heart disease.Estrogen also increases the risk of gallstones, which can block your gallbladder. If you have chest or abdominal pain, you should see a medical professional right away.Estrogen can cause increased blood pressure. This can be counteracted by taking it with spironolactone, which tends to lower blood pressure. If you can’t take spironolactone, there are other changes that can be tried, including other types of medication, exercise, and changes to diet.

In some MTFs estrogen causes nausea and vomiting, similar to morning sickness in pregnant women. Estrogen can also cause headaches or migraines. If you are getting frequent headaches/migraines or the pain is unusually bad, or if you are vomiting for more than a couple of days, talk to a health professional.

With breast growth there is often an increase in milky discharge from the nipples ( galactorrhea). This caused by the estrogen stimulating the production of the hormone prolactin, which in turn stimulates breast ducts to form milk. It is not known whether this increases the risk of non-cancerous tumours of the pituitary gland, which produces prolactin (prolactinoma). Although prolactinoma is usually not life-threatening, it can damage vision and cause headaches. For this reason, blood levels of prolactin are usually checked for at least three years when you start taking estrogen, and further tests may be ordered if prolactin levels are very high or if prolactinoma is suspected.

It is not known if estrogen increases the risks of breast cancer. There have been cases of MTFs who have developed breast cancer after starting hormones. Risks of breast cancer are increased if you have a family history of breast cancer, have been taking estrogen and/or progestagens for more than 5 years, are age 50+, or are overweight. Talk with your health care provider about screening tests that can be done to catch early signs of breast cancer.

Also Read: What Changes Can I Expect and How Soon on HRT


Side effects/risks of anti-androgens

Spironolactone affects the balance of water and salts in the kidneys. If the proportion of water and blood salts gets out of balance, you can have problems with low blood pressure or, rarely, high levels of potassium in the blood (this can cause changes to heart rhythm that may be life-threatening).The doctor/nurse who prescribes you hormones should check your potassium levels and kidney function on a regular basis if you:



  • have a history of kidney problems
  • are taking medication that can raise blood potassium (ask your doctor or pharmacist)
  • are taking ACE-inhibitors (e.g., Accupril®, Altace®, Capoten®, Coversyl®, Inhibace®, Lotensin®, Mavik®, Monopril®, Prinivil®, Vasotec®, Zestril®) – commonly prescribed for people with high blood pressure or heart problems


Spironolactone can also cause a skin rash. If this happens, see the doctor/nurse who prescribed the hormones.


Possible Side Effects/Risks  of Feminizing Hormones

Health Checkups While You’re Taking Hormones

As long as you are taking hormones (possibly the rest of your life), you need to have regular physical exams and lab tests to monitor your overall health. The first year after starting hormones, the prescribing doctor/nurse will want to see you at least every 3–4 months; after that, you will have appointments at least every 6 months. At each of these appointments, the doctor/nurse will likely:

  • ask questions about your overall health
  • check your blood pressure and your weight, and listen to your lungs
  • look at your arms, legs, hands, and feet to check your overall circulation as well as any signs of swelling, fluid retention, or pain
  • heck for early warning signs of health problems that can be caused by hormone therapy or made worse by hormone therapy (e.g., blood clots, heart disease, diabetes)
  • recommend blood tests to check your blood sugar, blood fats, blood cells, and liver health
  • recommend other tests as needed, depending on your health history, age, and any signs of possible health problems


It is not known whether hormone therapy increases MTFs’ risks for breast cancer. Depending on your age, family history, and other risks for breast cancer, your health care provider may recommend a yearly mammogram. If you are older than 50, your health care provider should check your prostate (via a finger in your rectum) once a year.

While the Transgender Health Program’s training for health care providers emphasizes the need to be creative and consider stopping hormones as a last resort (rather than a first resort), there are some health problems that make it dangerous to take hormones. If your health care provider suspects you have one of these conditions, they will try to control it through medical treatment and/or changes to your diet, exercise, or other lifestyle issues. If the condition can’t be controlled, you may be switched to another type of hormone, or your dose may be reduced or stopped until your other health problems get under control.

Maximizing the Benefits, Minimizing the Risks

There are a number of things that you can do to help ensure your hormone therapy is as effective and safe as possible:

  •  Be informed. Understanding how hormones work, what to expect, possible side effects/risks, and guidelines for care gives you the tools to be in charge of your health and to make informed decisions. Do your own research and ask questions.


  • If you smoke, stop or cut down. Smoking greatly increases the risks involved with hormone therapy. If you are a smoker, your estrogen level may have to be kept low.


  • Find a health care provider you trust and can be honest with. To get the most from hormone therapy, you need to be able to talk openly about what you want, concerns you have, and any problems you are experiencing. You also need to be able to talk openly with your health care provider about your health history, smoking, alcohol, street drugs, dietary supplements, herbs, and any other medication you are taking. Hormone therapy can be affected by all of these things, and being honest about them will help create a plan that is right for you.


  • Deal with problems early on. If caught early enough, most of the problems that can result from taking hormones can be dealt with in  a creative way that doesn’t involve stopping hormones completely. Waiting can worsen your health to the point where you can’t take hormones at all.


  • Don’t change medication on your own. Check with your health care provider if you want to start, stop, or change the dose of any of your medication. Taking medication more frequently or at a higher dose than prescribed increases health risks and can slow down the effects you want. Going against the instructions of your health care provider also erodes trust with them. If you want to change your medication, talk with your health provider first.


  • Take a holistic approach to your health. Health involves more than just hormone levels, and taking hormones is only one way for trans people to improve quality of life. Building a circle of care that includes health professionals, friends, partners, and other people who care about you will help support you to deal with other health problems as they come up, and to heal from societal transphobia.

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