Oestrogen Side Effects: Risks & What to Do

Oestrogen is used in hormone replacement therapy for menopausal symptoms, and as one of the two hormones in combined contraception. It comes as tablets, patches, gels, sprays and vaginal preparations.

How it is delivered changes the risk profile, and this is the most useful thing to understand.

Tablets pass through the liver first, which is why oral oestrogen is associated with a higher blood clot risk than skin preparations.
Patches, gels and sprays are absorbed through the skin and bypass that first pass, and are generally regarded as carrying a lower clot risk. This is often why they are preferred for people with clot risk factors.
Vaginal oestrogen for local symptoms such as dryness acts mainly where it is applied, with very little absorbed into the bloodstream, so it does not carry the same systemic considerations.

A second essential point: if you still have a womb, oestrogen is not given on its own. It is combined with a progestogen to protect the lining of the womb, because unopposed oestrogen increases the risk of endometrial cancer. If you have been prescribed oestrogen alone and still have a womb, ask about this.

Common hormonal medicine side effects

Breast tenderness or enlargement
Nausea
Headaches
Bloating and fluid retention
Leg cramps
Breakthrough bleeding or spotting
Skin irritation under a patch

Many of these settle over the first few months as the body adjusts. Effects that persist often respond to a change in dose or a switch between tablet, patch and gel, which is worth asking about rather than stopping.

Bleeding, mood, skin, weight and cycle changes

Irregular bleeding is common in the first months of HRT. Bleeding that starts after a settled pattern, or that continues beyond the first months, should be reported and investigated rather than assumed to be part of settling. See HRT bleeding and spotting.

Mood changes, breast tenderness and bloating are the effects most often reported early. Distinguishing HRT side effects from continuing menopausal symptoms can be difficult, and is worth discussing rather than guessing. See menopause symptoms compared with HRT side effects.

Serious warning signs that need medical attention

Get emergency help for signs of a clot or stroke:

Pain, swelling, warmth or redness in one calf or thigh
Sudden breathlessness, chest pain worse on breathing in, or coughing up blood
Sudden severe headache unlike any you have had before
Weakness or numbness on one side, difficulty speaking, or sudden loss of vision
Severe abdominal pain, or yellowing of the eyes or skin

See hormonal medicine and blood clot symptoms.

Contact a doctor promptly for unexpected vaginal bleeding, a new breast lump, a marked rise in blood pressure, or severe persistent headaches.

Who may be at higher risk?

Tell your clinician about a personal or family history of blood clots, a history of breast or other hormone-sensitive cancer, liver conditions, high blood pressure, migraine with aura, or unexplained vaginal bleeding not yet investigated.

Several of these are reasons to consider a skin preparation rather than tablets, or a local vaginal preparation, rather than reasons to have nothing at all. See HRT risks and side effects.

What to discuss with your doctor, pharmacist or clinic

Given my history, would a patch or gel suit me better than tablets?
Do I need a progestogen alongside this?
What bleeding is expected, and what should I report?
Would a local vaginal preparation address my main symptom?
When should this be reviewed?

Related contraception, HRT and hormonal medicine guides

See also HRT patches, HRT gel and HRT tablets.

Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.