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topical · for cold sores

Licorice Root (Glycyrrhizin) Topical

Reviewed by the Nimbera editorial team · Last updated May 2026

Wang et al. (2015, PMID 26579460) review in Acta Pharm Sin B documented that glycyrrhizin inhibits intercellular adhesion in HSV infection and demonstrates antiviral activity against HSV-1 and HSV-2 in preclinical models. Human topical RCT data specific to herpes labialis is limited; most evidence is in-vitro or animal-based.$10-$20 per tube

How to use

Apply a cream or gel containing deglycyrrhizinated licorice (DGL) extract or glycyrrhizin directly to the cold sore 3-4 times daily. Some formulations combine glycyrrhizin with zinc or antioxidants. Use at the first sign of prodrome for best effect.

How it works

Glycyrrhizin, the primary bioactive triterpene in licorice root, disrupts HSV lipid envelope integrity, inhibits viral particle attachment to host cells, and modulates inflammatory cytokine signalling involved in lesion severity.

Where to buy

Health food stores and online; look for topical licorice-root lip balms or creams. Integrated formulas combining licorice with zinc or propolis are available from brands such as Quantum Health and Boiron.

Typical cost: $10-$20 per tube

Safety notes

Topical DGL or glycyrrhizin cream at standard concentrations is not associated with the blood-pressure or hormonal effects of oral high-dose licorice. Do not take oral licorice root supplements for this purpose without medical advice - oral glycyrrhizin can cause pseudohyperaldosteronism, hypertension, and hypokalaemia at doses above 100 mg/day. Human clinical trial evidence for topical use is limited; use alongside proven antiviral measures.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Wang L et al., The antiviral and antimicrobial activities of licorice, a widely-used Chinese herb, Acta Pharm Sin B, 2015

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.