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Limited evidenceImmunity

Yin Qiao San

A classical Chinese formula built on honeysuckle and forsythia, taken at the first sign of a cold. One placebo-controlled trial is positive but was stopped early and badly underpowered.

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What the science says

  • Common cold symptoms Limited evidence

    A randomised, placebo-controlled, multicentre trial in Korea (where the formula is called Eunkyosan) found better symptom and quality-of-life scores on the WURSS-21 than placebo. It enrolled only 128 of a planned 375 participants before being terminated because of the COVID-19 pandemic, and the authors themselves call for a definitive full-scale study.

  • Quality of the wider trial base Limited evidence

    A PRISMA-compliant systematic review of randomised trials of the formula for the common cold found few studies, small samples and methodological weaknesses that prevented firm conclusions.

  • Antiviral mechanism Limited evidence

    Laboratory work reports antiviral and anti-inflammatory actions for constituents such as wogonin in cell and animal models. This explains plausibility but says nothing about clinical benefit.

Dosage & safety

Studied doseTraditional decoction or granules taken three times daily at the onset of symptoms; the Korean trial used a standardised granule preparation three times daily for up to eight days. Product strengths vary widely.
SafetyGenerally well tolerated over short courses, with no serious adverse events in the trial. Chinese patent medicines are variably regulated and have been found adulterated with pharmaceuticals or contaminated with heavy metals, so brand matters. Avoid in pregnancy without professional advice. Not a substitute for medical care if symptoms are severe or persist beyond about ten days.

How to take it

TimingThree times daily starting at the very first symptoms — the traditional indication is the first day or two, not an established cold.
With food?With warm water, between meals.
Worth knowingBrand matters more than dose here: Chinese patent medicines have been found adulterated with pharmaceuticals, so buy from a regulated supplier.

Interactions

With medications

  • diuretics and corticosteroids

    The liquorice in the classical formula adds to potassium loss and fluid retention. keep courses short and check with your doctor if you take these regularly

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does yin qiao san work for colds?

Yin Qiao San has limited evidence: one placebo-controlled Korean trial found better cold symptom scores, but it enrolled only 128 of a planned 375 participants before being stopped early. The wider trial base is small and methodologically weak.

When should I take yin qiao san?

Take Yin Qiao San three times daily with warm water starting at the very first symptoms, traditionally within the first day or two rather than in an established cold. The Korean trial used granules three times daily for up to eight days.

Is yin qiao san safe?

Yin Qiao San was well tolerated over short courses in its trial, but Chinese patent medicines have been found adulterated with pharmaceuticals or contaminated with heavy metals, so buy from a regulated supplier. Avoid it in pregnancy without professional advice, and seek care if symptoms are severe or last beyond about ten days.

Scientific references

Related in Immunity

Herbal medicines: what the evidence says (335)