Body-identical hormones: what the term means and what it does not

The ovaries produce estradiol and progesterone. Body-identical HRT uses hormones with the same structure, usually made from plant sources and processed in a laboratory. Other HRT products use different molecules, such as conjugated equine oestrogens or synthetic progestogens, which act on the same receptors but are not identical. All of these can be licensed and effective. The difference is in chemistry, not necessarily in outcomes.

• Estradiol as patches, gels, sprays and tablets.

• Micronised progesterone taken by mouth, used with oestrogen to protect the womb lining.

• Vaginal estradiol and estriol products for local symptoms.

• Combined products that contain estradiol with a progestogen.

Large trials of HRT have used a mix of products. Observational studies suggest that transdermal estradiol is not linked to increased clotting risk and that micronised progesterone may carry a lower breast cancer risk than some synthetic progestogens, although the data are not conclusive and not all studies agree. Professional bodies, including the British Menopause Society, say that licensed body-identical products are a reasonable first choice but that evidence does not allow strong claims about superiority.

The word "bioidentical" has been used in marketing for compounded hormone preparations, including creams, troches and pellets made by specialised pharmacies. These are not covered by the same evidence on dose, quality or endometrial safety, and professional bodies advise against them. Marketing that claims they are natural or safer than regulated products is not supported by the evidence.

Ask whether the product is licensed in the UK, what the active ingredients are, how it protects the womb lining if you need that, and what the monitoring plan is. Ask about the evidence for the claims being made. A clinician who is confident about a product should be able to answer clearly.

Many body-identical products are on NHS formularies, though some are not available in every area, and brand shortages have occurred in the past. If your preferred product is not available, a clinician can suggest a licensed alternative. Prescription charges in England can be capped through the HRT prepayment certificate, which covers all HRT items for a fixed annual fee.

Every licensed product comes with a patient information leaflet that lists the active ingredient, the dose, how to use it, side effects and what to do if you miss a dose. Look for the name of the hormone, such as estradiol or micronised progesterone, rather than relying on a marketing term. A pharmacist can confirm whether a product is licensed and whether it contains a body-identical hormone. If a clinic cannot tell you exactly what a product contains, treat that as a reason to pause and ask for the details in writing.