Black Cohosh and Other Herbal Options for Menopause: What the Evidence Shows

Direct answer

Black cohosh, red clover, evening primrose oil and St. John’s wort differ in what they contain, what researchers have tested and what safety questions they raise. Current evidence does not support assuming they will change menopausal hot flashes or night sweats. If you have already tried one and noticed little difference, check the exact preparation and review your symptoms and medicines with a pharmacist or clinician before adding another. [1] [2] [3] [4] [5]

Key points

• Evidence about one extract does not apply automatically to a different extract or a multi-ingredient product.
• Black cohosh has a liver-safety signal from reports. Those reports do not establish the cause in every case.
• Red clover contains isoflavones. Evening primrose oil is a seed oil. St. John’s wort has important medication interactions.
• Equol is a specific molecule with a different research pathway from these herbs. That distinction says nothing by itself about comparative outcomes.

Scientific background

Herbal products can be sold as powdered plants, extracts, oils or mixtures. The same plant name on two labels can refer to products made with different plant parts, extraction methods or concentrations. A study of an identified extract gives information about that extract under the study conditions. An herbal blend adds another layer of uncertainty because it may be impossible to tell which part contributed to a finding. [1] [2]

Equol research starts from a different question. Certain gut microbes can turn the soy isoflavone daidzein into S-equol. Red clover contains isoflavones, but taking a red-clover extract, eating soy and consuming an already formed molecule are three different exposures. Evening primrose oil supplies fatty acids and is a different kind of preparation again. Chemical differences help explain why the evidence has to be read separately. See Why Soy Doesn't Seem to Work for Some People for the metabolism. [3] [4] [6]

What the evidence examines

Black cohosh

The Herbal Alternatives for Menopause trial led by Newton compared black cohosh and multibotanical approaches with placebo and a hormone-therapy group. The black cohosh and botanical approaches did not show a consistent advantage over placebo for vasomotor symptoms. Other studies have assessed preparations that are not identical. The National Center for Complementary and Integrative Health notes that findings depend in part on what is studied and that the evidence is uncertain across products. [2] [7]

Rare reports of serious liver problems have involved people using products labelled as black cohosh. Attribution is uncertain, and some products have raised identity concerns. The safety question is worth discussing if you have liver disease or take medicines that can affect the liver. Seek medical advice promptly for yellowing of the skin or eyes, dark urine or other possible signs of liver trouble. [2]

Red clover

Red clover extracts contain plant compounds called isoflavones. Clinical studies in menopause have used different preparations and reported inconsistent results. A trial or evidence review has to specify what was tested and what it measured. If you have a hormone-sensitive condition or take ongoing medication, bring the exact ingredient label to a pharmacist or clinician. Evidence about longer-term use and safety in particular groups is limited. [3] [8]

Evening primrose oil

Evening primrose oil comes from the seeds of the plant and contains gamma-linolenic acid. The presence of that fatty acid does not demonstrate an effect on temperature regulation. NCCIH finds insufficient evidence to support evening primrose oil for any health condition. Reported side effects include digestive symptoms. Ask a pharmacist to check the specific product if you take medicines or are considering using several supplements together. [4]

St. John’s wort

Some people encounter St. John’s wort through information about mood. That evidence does not answer whether it changes menopausal hot flashes or night sweats. This herb can reduce the effectiveness of some medicines, including certain contraceptives and transplant medicines. Combining it with medicines that act on serotonin can also be dangerous. Check with a pharmacist or prescriber before starting or stopping it if you take any medicines. [1] [5]

Why it matters

If you tried an herb and felt no clear difference

Start by identifying what you took. Keep the package or photograph its ingredient list, directions and Canadian licence number if it has one. Note when you started, what you were hoping would change and whether anything unexpected happened. If you were looking for fewer night sweats, record that separately from feeling better rested. An interval with no clear change is a reason to reassess what you need help with.

Next, consider whether your symptom has become more disruptive or changed in character. If sleep, concentration or work is suffering, take the record to an appointment. If you suspect a side effect or an interaction, seek advice and include all prescription and non-prescription medicines in the review. Stacking products can make it harder to tell which ingredient caused a problem. [1] [2] [4] [5]

What this does not establish / limitations

Small trials can miss effects or overstate early findings. Differences in extract, length of follow-up and the way researchers count episodes make comparisons difficult. Symptom changes in the placebo group also matter because symptoms often vary over time. Reports of possible harms can flag a problem even when they cannot determine how often it happens or establish cause. Ingredient mechanisms are a starting point for research, with clinical outcomes requiring their own evidence. [1] [2] [7] [8]

Evidence context

The black cohosh trial is human intervention evidence for the preparations studied. NCCIH fact sheets synthesize evidence and safety information. The Menopause Society statement weighs the clinical literature and does not recommend herbal or dietary supplements as a general strategy for vasomotor symptoms. Equol formation research describes metabolism. Comparing these different evidence types helps explain why the presence of a plant compound or metabolite does not settle the clinical question. [1] [2] [6] [7]

Relationship to DR.MORGAN

Morgan Natural Health Products Inc. publishes the DR.MORGAN Science Journal. This article explains ingredients and how to interpret evidence and safety information.

When to talk to a health professional

Arrange a medication review before adding a herb if you take regular medicines, have liver disease or have a history of a hormone-sensitive condition. Ask for assessment if symptoms keep disrupting sleep, or if a new symptom or possible adverse effect begins after you start something. Bring the label or a photo of it. [1] [2] [3] [4] [5]

Contact a clinician promptly for bleeding that soaks through menstrual protection or includes large clots, bleeding between periods, any bleeding after 12 months without a period, or periods stopping unexpectedly before age 40. Seek emergency care if heavy bleeding comes with fainting or severe light-headedness. [9] [10] [11]

References

1. North American Menopause Society. 2023 nonhormone therapy position statement. Full statement.
2. NCCIH. Black Cohosh: Usefulness and Safety.
3. NCCIH. Red Clover: Usefulness and Safety.
4. NCCIH. Evening Primrose Oil: Usefulness and Safety.
5. NCCIH. St. John’s Wort and Depression: In Depth.
6. Setchell KDR, Clerici C. Equol: history, chemistry, and formation. J Nutr. 2010. Full text.
7. Newton KM, et al. Treatment of vasomotor symptoms of menopause with black cohosh, multibotanicals, soy, hormone therapy, or placebo. Ann Intern Med. 2006. DOI: 10.7326/0003-4819-145-12-200612190-00003.
8. Lethaby A, et al. Phytoestrogens for menopausal vasomotor symptoms. Cochrane Database Syst Rev. 2013. DOI: 10.1002/14651858.CD001395.pub4.
9. MyHealth Alberta. Abnormal Vaginal Bleeding.
10. MyHealth Alberta. Vaginal Bleeding After Menopause.
11. MyHealth Alberta. Primary Ovarian Insufficiency.

Related reading

• How Much Soy Would You Have to Eat?
• Why Soy Doesn't Seem to Work for Some People
• Natural Approaches to Hot Flashes

FAQ

Is black cohosh safe for everyone?

Individual risks vary. Discuss it before using it if you have liver concerns or take other medicines, and seek advice for possible liver symptoms. [2]

Do red clover and soy contain the same things?

Both contain isoflavones. The mixture and the form differ, and an extract and a food can have quite different exposures. [3] [6] [8]

Can I take St. John’s wort alongside a prescription?

Ask a pharmacist or prescriber first. It can have serious interactions with some prescriptions, including medicines used for contraception, transplantation and mood. [5]

What if a herb did not make a difference?

Write down the exact preparation, what you were tracking and any side effects. Discuss the underlying symptoms and your options before adding another herb or combining several. [1]