March 22, 2018 4 min read

In our experience at MSH, trans females or non-binary individuals requesting Gender Affirming Hormone Treatment feel great on oestrogen.  We always start with a low dose and work up slowly to avoid unwanted side-effects.  The following side-effects may occur at any dose but is more likely to happen at higher dosages.  Most of them disappear after a few days. If you read the list, you may be inclined to think that no person should ever take the risk of taking hormones! But in actuality, most people experience only benefits and no side-effects from oestrogen.  It is however important to be knowledgeable about all the risks and make an informed decision. The most important side-effects are those that might be a sign of having a blood clot or an embolism (where the blood clot dislodges into the lung or brain). Those are marked in bold. If you suspect that you might have a blood clot, you will need to have it investigated immediately.  If your doctor is not available, you will have to go to the emergency department of your nearest hospital and say that you are on oestrogen therapy and suspect that you have a blood clot.  In our practice we are aware of one cis-female who developed a blood clot on hormones, but that was also due to an uncontrolled inflammatory disease in her colon. It is a rare side-effect, but very serious if it does occur.  If you smoke, you have a much higher risk to develop a blood clot.  You are advised against taking oestrogen if you are smoking.  You are also advised against taking oestrogen if you have known heart disease. Along with its needed effects, oestradiol (the active ingredient contained in oestrogen implants, patches, creams, gels and pills) may cause some unwanted effects. Although most of these side effects are vary rare, they have been reported in clinical trials and/or in real-life situations.  It is not known if the reported cases are directly due to oestrogen in all cases, but here is the list:


  • clear or bloody discharge from the nipple
  • dimpling of the breast skin
  • inverted nipple
  • lump in the breast or under the arm
  • persistent crusting or scaling of the nipple
  • redness or swelling of the breast
  • sore on the skin of the breast that does not heal
  • pain
  • milky discharge
  • non-cancerous breast growths
  • breast cancer

Central Nervous System:

  • irritability
  • feeling sad or empty
  • lack of appetite
  • tiredness
  • trouble concentrating
  • trouble sleeping
  • headache
  • migraine
  • dizziness
  • vertigo
  • aggravation of epilepsy
  • feeling of pins and needles (if in both hands/feet it is unlikely to be a sign of a blood clot, but if it is in only one limb, it could be a sign of a blood clot)
  • depression
  • nervousness
  • mood swings
  • change in libido
  • anxiety

Heart and lungs:

  • fast heartbeat
  • noisy, rattling breathing
  • tightness in the chest
  • trouble breathing when at rest
  • trouble breathing or swallowing
  • changes in blood pressure – high blood pressure or low blood pressure
  • venothrombo-embolism (when a blood clot dislodges into your lung or brain)
  • upper respiratory tract infection
  • heart attack
  • stroke


  • hives, itching, or rash
  • Redness
  • If redness is associated with swelling and pain, it could be a sign of a blood clot
  • Varicose veins (if painful they could be a sign of a blood clot, but usually not a dangerous one. Still advisable to seek medical attention)
  • skin discoloration
  • acne
  • alopecia (loss of hair)
  • hyperhidrosis (excessive sweating in certain areas)
  • night sweats
  • eczema

With implants:

  • local reaction to the oestradiol implant
  • infection at the implant site
  • bleeding at the implant side
  • non-healing of the implant wound
  • erosion of the implant through the skin
  • scarring of the implant wound
  • scar tissue formation in the tract made for the implant
  • damage to nerves and blood vessels around the implant
  • pain at the site of the implant
  • oestrogen overdose
  • allergic reaction to the local anaesthetic used
  • allergic reaction to the plaster/steri-strip used


  • decrease in the amount of urine
  • pain or feeling of pressure in the pelvis
  • diarrhoea
  • abdominal pain
  • flatulence
  • nausea and vomiting
  • abdominal distension


  • deep vein thrombosis (a blood clot, usually in your lower leg, but it can occur anywhere)
  • fever or chills
  • hot flushes
  • joint pain, stiffness, or swelling
  • pain, redness, or swelling in the arm or leg
  • swelling of the eyelids, face, fingers, lips, hands, feet, or lower legs
  • back pain
  • headache and migraine
  • weight gain
  • ear congestion
  • loss of voice or hoarseness
  • nasal congestion
  • runny nose
  • sneezing
  • sore throat
  • leg cramps
  • visual disturbances
  • abnormal liver tests
  • jaundice
  • fluid retention
  • allergic reaction, including anaphylactic shock

Possible Symptoms of Oestradiol Overdose:

  • dizziness
  • drowsiness
  • nausea
  • stomach pain
  • tenderness of the breasts
  • unusual tiredness or weakness
  • vomiting
Some side effects of oestradiol may occur that usually do not warrant medical attention. These side effects may go away during treatment as your body adjusts to the medicine.  If you are worried at all, experiencing worsening of side-effects or are experiencing a serious side-effect, please contact your doctor immediately.  If your doctor is not available, you will have to go to the emergency department of your nearest hospital. This document was adapted from: with additional information added.  
Dr Elna Rudolph
Written by Dr Elna Rudolph – Medical Doctor, Sexologist and Clinical Head of My Sexual Health. 086 7272950
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