Body-identical HRT: what the term means and how it compares

Hormone replacement therapy (HRT) replaces hormones that the body produces less of during the menopause, mainly oestrogen and progestogen. "Body-identical" and "bioidentical" are popular, not formal, terms for hormones whose molecular structure matches what the body makes. In HRT this usually means oestradiol, a form of oestrogen, and micronised progesterone, a form of progesterone.

The BMS uses more careful wording. It defines regulated bioidentical HRT (rBHRT) as precise duplicates of human hormones developed conventionally by the pharmaceutical industry and authorised by regulators such as the MHRA. These are ordinary licensed medicines that a GP or menopause clinician can prescribe. The word "body-identical" is therefore a description of ingredients, not of a separate or specially tailored treatment.

The BMS defines compounded bioidentical HRT (cBHRT) as precise duplicates of human hormones produced by specialist pharmacies that do not follow the same MHRA regulatory pathway as conventional products. Its consensus statement, reviewed in April 2026, says prescribing cBHRT is not recommended by national or international guidance, and that cBHRT products are not evidence based for effectiveness and safety.

It also says there is insufficient evidence to justify the multiple serum and saliva hormone tests often claimed to individualise cBHRT, and that claims for the benefits of cBHRT have largely been extrapolated from studies of conventional regulated products. Its advice is that menopause care should be underpinned by national and international guidance and, wherever possible, regulated products should be prescribed.

The NHS describes HRT as containing oestrogen, progestogen or both, taken or used in different ways, and on different schedules (cyclical or continuous). The type that suits a person depends on whether they have had a hysterectomy, what stage of menopause they are at and their preferences. The NHS says you may need to try different brands and methods to find the one that suits you.

• Tablets, usually once a day. The NHS notes that some risks, such as blood clots, are higher with tablets than with patches, gel or spray, although the overall risk is still small.

• Skin patches, changed every few days. They may suit people who have difficulty swallowing tablets, and unlike tablets do not increase the risk of blood clots.

• Oestrogen gel, smoothed on once a day. It can take 5 minutes or more to dry, and does not increase clot risk.

• Oestrogen spray, applied to the inner arm or inner thigh. The NHS says to wait an hour before a bath or shower.

• A hormonal intrauterine system, which the NHS says can supply the progestogen needed alongside oestrogen if you have a womb.

• Vaginal oestrogen, which the NHS says helps with vaginal dryness and does not carry the usual HRT risks, but will not help with hot flushes or sleep.

The BMS says studies of regulated bioidentical HRT have shown some advantages over other types of HRT, particularly those containing androgenic progestogens, but it also says further data from larger studies on major cardiovascular and breast outcomes are needed to confirm the potential benefits. In plain terms, the ingredients are attractive on paper, but the claim that this combination is clearly safer than every alternative is not yet settled.

The NHS does not use the term body-identical on its HRT pages. It describes micronised progesterone as capsules used with oestrogen for menopause symptoms, and lists the forms above. If a clinic describes a product as body-identical, it is reasonable to ask whether it is a licensed product and which ingredients and routes it uses.

The NHS says the benefits of HRT usually outweigh the risks, and that for someone under 60 with menopause symptoms who is not at high risk of breast cancer or blood clots the benefits are likely to outweigh the risks. The main benefit is relief of symptoms such as hot flushes, night sweats, sleep problems, anxiety and low mood caused by the menopause, and vaginal dryness. HRT also helps prevent osteoporosis and can help maintain muscle strength.

The NHS gives the main risks. HRT can slightly increase the risk of breast cancer: around 5 extra cases in every 1,000 women who take combined HRT for 5 years, with the risk rising the longer it is taken and falling again after stopping. There is little or no increase in breast cancer risk from oestrogen-only HRT. Tablets can slightly raise the risk of blood clots and stroke, but patches, gel and spray do not raise clot risk. It also says it is especially important to attend breast screening appointments if you take HRT.

The NHS says it is common to have no side effects or only mild ones, and that side effects usually improve over time, so it suggests continuing for at least 3 months if possible. Oestrogen side effects can include headaches, breast tenderness, nausea, mood changes, leg cramps and unexpected vaginal bleeding or spotting, and progestogen can cause changes in periods, breast tenderness, mood changes and acne. Irregular bleeding is common in the first months and usually settles within 6 months.

It advises speaking to a GP if side effects are severe or last longer than 3 months, if bleeding becomes heavier, continues beyond 6 months, or returns after you had stopped having periods. Suspected side effects of any medicine can be reported through the Yellow Card scheme run by the MHRA.

The NHS says it is your choice whether to take HRT and when to start, and you do not need to wait until symptoms are severe. You will usually take HRT for 2 to 5 years, although it can be longer, and there is no fixed limit. It is best to take it only as long as the benefits outweigh the risks, with a review each year. After the age of 60 the balance may shift, and a GP may suggest a low dose, using patches or gel rather than tablets.

When stopping, the NHS says you can stop suddenly, but it is usually recommended to reduce gradually over 3 to 6 months, and that symptoms may return for a short time. People with premature menopause (before 40) or early menopause (before 45) are usually advised to take HRT until at least 51.

Licensed HRT, including the oestradiol and micronised progesterone combination, can be prescribed by a GP or a menopause clinician, and you do not need a specialist compounding service to receive it. Private menopause clinics are another route to consultation. Whichever route you use, it is sensible to ask whether the products are licensed in the UK, what monitoring and review will be arranged, and who will continue the prescription. Be cautious about any service that relies on repeated saliva or blood hormone testing to set doses, in view of the BMS statement above.