Perimenopause herbal supplements: what the evidence shows

You would rather try something natural first. That's a completely reasonable instinct, and the shelves are full of products designed to meet it — black cohosh, red clover, sage, evening primrose, all in packaging that suggests a gentler route to the same place.

I'll declare the interest immediately: Perimae doesn't sell any of these, and doesn't intend to. So read what follows knowing I have nothing to gain from talking you out of them. What I'd like to give you instead is what the evidence actually says, and one piece of information about the labelling that I think most people have never been told.

The short version

• The Cochrane review of black cohosh — 16 trials, 2,027 women — concluded there is insufficient evidence to support its use.
• The MHRA has concluded the evidence supports an association between black cohosh and liver toxicity.
• The Cochrane review of phytoestrogens including red clover — 43 trials, 4,084 women — found no conclusive evidence they reduce hot flushes or night sweats.
• The THR logo is not proof that something works. It certifies 30 years of traditional use, not clinical evidence.
• Several of these interact with other medicines, and some are not advised for women who've had breast cancer.

Black cohosh

The most-sold of them, and the one with the most research behind it.

The Cochrane review, published in 2012, pooled 16 randomised controlled trials covering 2,027 perimenopausal and postmenopausal women. Its conclusion: "There is currently insufficient evidence to support the use of black cohosh for menopausal symptoms." The reviewers noted the quality of the trials was generally unclear, because methods were inadequately reported.

On safety, they were equally blunt — the evidence was "inconclusive, owing to poor reporting." Not reassuring; simply not documented well enough to say.

Then there's the liver. The MHRA's public assessment report on black cohosh and liver injury concluded that "the available evidence supports an association between black cohosh and risk of liver toxicity", while acknowledging the exact level of risk was difficult to establish. It counted 21 UK Yellow Card reports of liver reactions, of which 14 appeared to support an association, alongside cases reported in Germany and Australia. The Committees recommended that warnings about rare liver reactions be added to product information for both licensed and unlicensed products.

Rare. But real enough that the regulator required a warning.

Where the sources disagree — and they do

I'm not going to smooth this over, because it's the honest state of play.

Cochrane says insufficient evidence. Women's Health Concern — the patient arm of the British Menopause Society — says in its factsheet, amended July 2026, that black cohosh can help hot flushes, though "not as well as HRT". It also says it doesn't help anxiety or low mood, that it can interact with other medicines, that there are unknown risks regarding its safety, and that it should be avoided by women who've had breast cancer.

Those two positions aren't identical, and I can't reconcile them for you. A systematic review asks whether the trial evidence clears a bar; a clinical body also weighs experience and practice. What they agree on is that it isn't a strong effect, that safety isn't fully characterised, and that it isn't for everyone.

Red clover and other phytoestrogens

The Cochrane review here is larger: 43 randomised trials, 4,084 participants, published in 2013. The conclusion: "No conclusive evidence shows that phytoestrogen supplements effectively reduce the frequency or severity of hot flushes and night sweats."

Red clover specifically was tested in five trials of the branded extract Promensil, pooled together. No statistically significant difference from placebo in daily hot flush frequency.

Two things worth adding, because they cut both ways.

In its favour: the review found no evidence that these treatments caused oestrogenic stimulation of the endometrium or vagina, or other adverse effects, when used for up to two years. That's genuinely reassuring on safety.

Also in its favour: extracts high in genistein — above 30 mg a day — showed more consistent reductions in hot flushes across trials, and the reviewers flagged them as warranting further study. That's a signal, not a finding, and I'd rather report it as the loose end it is than leave it out.

Women's Health Concern describes red clover and isoflavone results as "variable", and does not recommend them for women who've had breast cancer.

The THR logo, and what it actually certifies

This is the part I most want you to know.

You'll see a THR mark — Traditional Herbal Registration — on many of these products, and it looks like an approval. Women's Health Concern advises looking for it, and rightly: it means correct dosage, good quality and suitable product information.

But here is what it does not mean.

Under the UK government's own guidance, a Traditional Herbal Registration is granted on the basis of traditional use, not clinical trial evidence of efficacy. To qualify, a product must show it has been traditionally used for the stated condition for a minimum of 30 years, at least 15 of them in the EU or EEA. And THRs are only granted "if the medicine is used for minor health conditions where medical supervision is not required". Anything claiming to treat a major condition needs a full marketing authorisation instead.

So the THR mark is a statement about quality and history. It tells you the product is what it says it is and that people have used it this way for a long time. It does not tell you it works.

That distinction is doing an enormous amount of quiet work on those shelves, and almost nobody explains it.

Interactions, and who should be careful

Herbal doesn't mean inert.

• Black cohosh interacts with other medicines, and is not advised if you've had breast cancer.
• St John's wort has shown benefit for vasomotor symptoms, but interacts with a long list of drugs. Women taking tamoxifen should not take it — it may make the tamoxifen less effective. That is a serious interaction, not a caution.
• Red clover and isoflavones are not recommended for women who've had breast cancer.

Women's Health Concern's broader point is worth repeating in full: unregulated herbal remedies "should not be considered safe", because there is much variety in their effectiveness and potency, and the potential for significant side effects or interactions.

If you take any regular medication, this is a conversation with a pharmacist, not a decision at a shelf.

Why we don't sell them

Three reasons, in order of weight.

The evidence isn't there. Two large Cochrane reviews, nearly 6,000 women between them, and neither could conclude these work. We couldn't sell them and hold to the standard we've set for everything else on this site.

The safety picture is incomplete. Not alarming, but not characterised — and on black cohosh specifically, the regulator has found enough to require a liver warning.

They belong to a different regulatory route. These sit under the traditional herbal medicines scheme, and we'd rather sell things whose claims come from the authorised list, in the approved wording, with the evidence behind them.

What I'd say instead

If your symptoms are affecting your daily life, the things with evidence behind them are on the NHS list: HRT, cognitive behavioural therapy for hot flushes and night sweats, and non-hormonal medicines where HRT isn't suitable. The NHS's own view of herbal remedies is that "there is very little evidence to show how well they work."

That's worth an appointment. We've written about when to see a doctor and about severe symptoms separately.

The uncomfortable bit

Wanting a gentler option isn't naive. It's often a reasonable response to being dismissed, or to being frightened by headlines about HRT, or to simply preferring to start with something small.

The trouble is that "natural" has been made to carry a promise it can't hold, and a certification mark about 30 years of tradition has been allowed to look like proof. You deserve to know which is which before you spend anything.