Estradiol (HRT) — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Estradiol (HRT)?
Estradiol is a naturally occurring oestrogen hormone used for menopausal hormone replacement therapy (HRT) and gender-affirming care. This medication is funded by Pharmac for menopausal symptoms and osteoporosis prevention.
What is Estradiol (HRT) Used For?
Estradiol is used in menopausal hormone replacement therapy (HRT) for the relief of vasomotor symptoms (hot flushes, night sweats), urogenital symptoms (vaginal dryness, dyspareunia), and prevention of postmenopausal osteoporosis. It is also used in gender-affirming hormone therapy.
How Does Estradiol (HRT) Work?
Estradiol binds to oestrogen receptors (ER-alpha and ER-beta) in target tissues, regulating the expression of genes involved in the development and maintenance of female secondary sex characteristics, bone metabolism, cardiovascular health, and neurological function. It reduces vasomotor symptoms by stabilising hypothalamic thermoregulation.
How to Take Estradiol (HRT)
Available as patches (Estraderm MX®, Estradot®), gel (EstroGel®, Sandrena®), oral tablets, and intravaginal cream/tablet/ring. Patches are changed every 3–4 days. Gel is applied daily to arm or thigh. For women with an intact uterus, a progestogen MUST be added to protect the uterine lining (combined HRT).
Common Side Effects of Estradiol (HRT)
- Breast tenderness
- Nausea
- Headache
- Fluid retention
- Vaginal spotting or bleeding
- Skin reaction at patch site
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Venous thromboembolism (increased risk — particularly with oral oestrogen; transdermal has lower risk)
- Breast cancer (modest increased risk with prolonged combined HRT — oestrogen-only HRT in hysterectomised women has lower breast cancer risk)
- Stroke (modest increased risk with oral oestrogen — lower with transdermal)
- Endometrial cancer (with oestrogen-only HRT in women with a uterus — prevented by adding progestogen)
Drug Interactions
Estradiol (HRT) may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Enzyme inducers (carbamazepine, rifampicin, St John’s Wort — reduce oestrogen levels)
- Anticoagulants (warfarin — variable effect)
- Ciclosporin (oestrogens may increase levels)
New Zealand Prescribing Information
Various estradiol preparations are funded by Pharmac: Estraderm MX® patches (25, 50, 100 mcg/24h); Estradot® patches; Sandrena® and EstroGel® gels. The New Zealand Menopause Society guidelines recommend transdermal (patch or gel) oestrogen as the preferred route due to lower VTE and stroke risk compared to oral oestrogen. Women with an intact uterus must use concurrent progestogen to prevent endometrial hyperplasia.
Frequently Asked Questions
Is hormone replacement therapy safe?
For most healthy women under 60 years of age or within 10 years of menopause, the benefits of HRT for quality of life and bone health generally outweigh the risks. The absolute risks of VTE and breast cancer depend on the type, dose, and duration of HRT, and your personal risk factors. A full discussion with your doctor is essential before starting.
What is the difference between patches and oral HRT?
Transdermal oestrogen (patches, gels) bypasses first-pass liver metabolism, which is why it carries a lower risk of VTE and stroke than oral oestrogen. For women at elevated VTE risk (obesity, family history, previous clot), transdermal is the preferred route.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: