Prunella Vulgaris (Self-Heal)
A mint-family herb used in Chinese medicine for thyroid nodules and, in the West, for herpes. The thyroid trials are small and low quality, and the antiviral work is entirely in cells and animals.
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What the science says
- Thyroid nodules Limited evidence
A meta-analysis of Chinese randomized trials reported that Prunella preparations added to standard care reduced thyroid nodule size. The included trials were small, poorly blinded and at high risk of bias, so the effect size is unreliable.
- Herpes simplex virus Limited evidence
Polysaccharide and lignin-carbohydrate fractions from Prunella block herpes simplex virus in cell culture and in animal models. No human trial has tested it for cold sores or genital herpes.
Dosage & safety
How to take it
Interactions
With medications
- levothyroxine and antithyroid drugs
Prunella has reported effects on thyroid function that could destabilise a settled dose. avoid it if you are treated for thyroid disease unless your doctor agrees
- blood pressure medication
It may lower blood pressure, adding to the drug's effect. monitor your blood pressure if you combine them
Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.
Frequently asked questions
Does prunella vulgaris (self-heal) shrink thyroid nodules?
The evidence is limited: a meta-analysis of Chinese trials reported smaller thyroid nodules when prunella was added to standard care, but the trials were small, poorly blinded and at high risk of bias.
Does self-heal work for cold sores or herpes?
No human trial has tested prunella vulgaris for cold sores or genital herpes. Its activity against herpes simplex virus has been shown only in cell culture and animal models, so the evidence is limited.
How much prunella vulgaris should I take?
Chinese trials used decoctions of roughly 15–30 g of dried spike per day. Western 500 mg prunella capsules, taken once or twice daily, are a different intervention whose dose has never been tested.
Is prunella safe with thyroid or blood pressure medication?
Prunella vulgaris may affect thyroid function and lower blood pressure, so avoid it with levothyroxine or antithyroid drugs unless your doctor agrees, and monitor your blood pressure if you take antihypertensives. Pregnant women should avoid it.
Scientific references
- Safety and efficacy of Prunella vulgaris preparation in adjuvant treatment of thyroid nodules: A meta-analysis
- Prunella vulgaris polysaccharide inhibits herpes simplex virus infection by blocking TLR-mediated NF-κB activation
- Chemical properties, mode of action, and in vivo anti-herpes activities of a lignin-carbohydrate complex from Prunella vulgaris
Related in Immunity
- Vitamin C Limited evidence
- Zinc Moderate evidence
- Elderberry Limited evidence
- L-Lysine Limited evidence
- Echinacea Limited evidence
- Andrographis Moderate evidence