Limited evidenceImmunity

Houttuynia Cordata

A pungent herb eaten as a vegetable and used medicinally across East Asia, with a strong laboratory record for antiviral and anti-inflammatory activity. Clinical evidence for colds and flu is missing.

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What the science says

Broad preclinical activity, no infection trials Limited evidence
An ethnopharmacological review documented antiviral, antibacterial and anti-inflammatory effects across many cell and animal studies, alongside a near-total absence of controlled clinical trials for respiratory infection.
One trial, in allergic rhinitis rather than colds Limited evidence
A randomized trial of a Houttuynia-based Chinese herbal formula reported improved allergic rhinitis symptoms. It tested a multi-herb formula in an allergic condition, so it does not support Houttuynia alone for viral infection.

Dosage & safety

Studied doseNo supplement dose is established. Traditional use is 15–30 g fresh herb or 5–10 g dried in decoction; capsule products follow their own labels.

SafetyOral use as food and tea has a long record of tolerability, with gastrointestinal upset the main complaint. Injectable Houttuynia preparations used in China were associated with serious allergic reactions and were restricted — that risk relates to injections, not oral use, but it signals real allergenic potential. Avoid in pregnancy; data in children are lacking.

How to take it

TimingTiming does not matter.

With food?With food, since stomach upset is the main complaint.

Worth knowingThe smell is strongly fishy and puts most people off capsules; brewing the dried herb as a tea is the form with the long food record behind it.

Frequently asked questions

Does houttuynia cordata work for colds or flu?

Clinical evidence for houttuynia in colds and flu is missing, so the grade is limited. Its antiviral and anti-inflammatory activity comes from cell and animal studies, with almost no controlled trials for respiratory infection.

Does houttuynia help allergic rhinitis?

One randomized trial of a houttuynia-based multi-herb Chinese formula reported improved allergic rhinitis symptoms. Because it tested a formula, it does not show that houttuynia alone works, so the evidence is limited.

Is houttuynia safe to take?

Oral houttuynia as food and tea has a long record of tolerability, with stomach upset the main complaint. Injectable houttuynia was restricted in China after serious allergic reactions, which signals real allergenic potential; avoid it in pregnancy.

How much houttuynia should I take?

No supplement dose of houttuynia is established. Traditional use is 15–30 g of fresh herb or 5–10 g dried in a decoction, and brewing the dried herb as tea is the form with the long food record.

Scientific references

Houttuynia cordata Thunb: An Ethnopharmacological Review
Wu Z, Deng X, Hu Q, Xiao X, Jiang J, Ma X, Wu M — Front Pharmacol, 2021
A Houttuynia cordata-based Chinese herbal formula improved symptoms of allergic rhinitis during the COVID-19 pandemic
Chang KW, Lin TY, Fu SL, Ping YH, Chen FP, Kung YY — J Chin Med Assoc, 2022

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Herbal medicines: what the evidence says (335)