Si Wu Tang
The four-herb blood tonic that underlies most Chinese gynaecological formulas, used for irregular or painful periods. A meta-analysis of its Taohong variant in period pain is positive, but it pools small unblinded Chinese-language trials, so the result should be treated as a hypothesis.
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What the science says
- Taohong Si Wu Tang for primary dysmenorrhoea Limited evidence
A systematic review and meta-analysis in Explore pooled randomized trials of Taohong Siwu Tang for primary dysmenorrhoea and reported reduced pain compared with control. The primary studies were small, mostly unblinded, and used varying comparators, so the pooled effect is likely optimistic.
- Base formula itself is barely studied clinically Limited evidence
Almost all clinical work uses modified versions (Taohong, Xiangfu and others) rather than plain Si Wu Tang, and a Chinese-language research review of the Siwu series notes that mechanistic and animal work substantially outweighs clinical evidence.
- Mechanistic research is preclinical Limited evidence
Recent Si-Wu-Tang studies concern gut microbiota, liver steatosis and ovarian insufficiency in rodent models. None of these findings have been tested in people.
Dosage & safety
How to take it
Interactions
With medications
- warfarin, antiplatelets and other anticoagulants
Dang gui and chuan xiong both have antiplatelet activity that adds to these drugs. Do not combine without medical supervision, and stop two weeks before surgery
- diuretics and blood pressure medication
Versions of the formula that include liquorice cause potassium loss and fluid retention. Check the ingredient list and avoid prolonged use if you take these drugs
With other supplements
- fish oil, ginkgo, vitamin E or garlic extracts
Additive effect on platelet function. Avoid stacking several antiplatelet supplements
Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.
Frequently asked questions
Does si wu tang help period pain?
A meta-analysis of the Taohong variant of si wu tang reported reduced period pain, but it pooled small, mostly unblinded Chinese-language trials, so the result is a hypothesis and the evidence is limited. Plain si wu tang is barely studied clinically.
How do you take si wu tang?
Si wu tang is traditionally taken twice daily in the week before menstruation rather than continuously; granule forms usually state 6–9 g twice daily. Stop it once bleeding is heavy, because its blood-moving herbs are the wrong choice during a heavy flow.
Can you take si wu tang with blood thinners?
Not without medical supervision: dang gui and chuan xiong in si wu tang have antiplatelet activity that adds to warfarin and other anticoagulants. Stop it two weeks before surgery.
Is si wu tang safe for heavy or persistent period pain?
Heavy or persistent period pain deserves investigation for endometriosis or fibroids rather than long-term self-treatment with si wu tang. Avoid self-prescribing it in pregnancy.
Scientific references
Related in Women's health
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