Are bioidentical hormones safe?

It depends what you mean. Regulated “body-identical” hormones — used in standard, prescribed HRT — are safe and well-studied. Unregulated “compounded bioidentical” hormones (cBHT) are a different thing, and are not recommended.

This is a confusing area because the marketing blurs two very different products. Body-identical hormones have the same molecular structure as the hormones your body makes, and modern, regulated HRT widely uses them (for example, transdermal oestradiol and micronised progesterone) — these are evidence-based and recommended. Compounded bioidentical hormones (cBHT), by contrast, are custom-mixed by specialist pharmacies, often marketed as “natural” and tailored via saliva testing. Major medical bodies advise against cBHT because it isn't regulated or quality-controlled, the dosing is unreliable, saliva testing isn't accurate, and safety hasn't been properly tested.

So “bioidentical” isn't automatically safer or more natural — the regulated version is excellent; the compounded version is the one to avoid.

What to do: if you want body-identical hormones, you can get regulated, well-studied versions through standard prescribed HRT — ask your GP or a menopause specialist for transdermal oestrogen and micronised progesterone. Be cautious of clinics selling expensive compounded “bioidentical” hormones with saliva testing, which mainstream guidance does not support.