Licorice Root Extract Research

Licorice Root Extract is being studied for its anti-viral effects. In laboratory studies using cells, hen eggs and animals it has a protective effect against:

  • Influenza (and SARS)
  • Influenza A (Avian Influenza, Bird Flu)
  • HIV
  • Hepatitis B
  • Herpes simplex
  • It is active against a variety of DNA and RNA viruses.

The quotations from recent research articles below indicate the current state of research on licorice root extract.

Influenza and Licorice Root Extract

Article 1: "The antiviral effect of glycyrrhizin (GR), an active component of licorice roots, was investigated in mice infected with influenza virus A2 (H2N2). When mice that had been exposed to 10 50% lethal doses of the virus were treated intraperitoneally with 10 mg of GR per kg of body weight 1 day before infection and 1 and 4 days postinfection, all of the mice survived over the 21-day experimental period. At the end of this period, the mean survival time (in days) for control mice treated with saline was 10.5 days, and there were no survivors."
PMID: 9055991 (Galveston, USA)

Article 2: "Glycyrrhizic acid, at doses well tolerated by the cells in monolayer cultures, inhibited the recovery of hemagglutinins from both Influenza and Newcastle Disease virus-infected embryonated hen eggs. Since the drug had no effect on viral viability and did not impair the hemagglutinating activity of the virions, the growth of viruses into the embryo tissues might be mainly affected. Late viral replication steps, rather than the early ones, appeared to be involved in the inhibitory effect of glycyrrhizic acid."
PMID: 6633273

Article 3: "The outbreak of SARS warrants the search for antiviral compounds to treat the disease... We assessed the antiviral potential of ribavirin, 6-azauridine, pyrazofurin, mycophenolic acid, and glycyrrhizin against two clinical isolates of coronavirus (FFM-1 and FFM-2) from patients with SARS admitted to the clinical centre of Frankfurt University, Germany. Of all the compounds, glycyrrhizin was the most active in inhibiting replication of the SARS-associated virus."
PMID: 12814717 (Frankfurt, Germany)

HIV, Avian Influenza and Licorice Root Extract

Article 1: "Cell entry of enveloped viruses requires a wide-fusion-pore mechanism, involving clustering of fusion-activated proteins and fluidization of the plasma membrane and viral envelope. In the present study, GL (glycyrrhizin) is reported to lower membrane fluidity, thus suppressing infection by HIV, influenza A virus and vesicular stomatitis virus, but not by poliovirus. GL-treated HIV-1 particles showed reduced infectivity. GL also inhibited cell-to-cell fusion induced by HIV-1 and HTLV-I (human T-cell leukaemia virus type I). However, when cells treated with 1 mg/ml GL were placed in GL-free medium, they showed increased susceptibility to HIV-1 infection and HTLV-I fusion due to enhancement of membrane fluidity. The membrane dependence of GL and GL removal experiments suggest that GL does affect the cell entry of viruses. HIVs with more gp120 were less dependent on temperature and less sensitive to GL treatment than those with less gp120, indicating that the existence of more gp120 molecules resulted in a higher probability of forming a cluster of fusion-activated proteins."
PMID: 16053446 (Kumamoto, Japan)

Hepatitis and Licorice Root Extract

Article 1: "Glycyrrhizin, a major component of a herb (licorice), has been intravenously used for the treatment of chronic hepatitis B in Japan and improves liver function with occasional complete recovery from hepatitis. This substance modifies the intracellular transport and suppresses sialylation of hepatitis B virus (HBV) surface antigen (HBsAg) in vitro. This study was designed to clarify the pharmacological basis for its effectiveness. ... When glycyrrhizin attained these concentrations in the cellular fraction of the ... cell culture, it suppressed the secretion of HBsAg as reported previously. These results indicated that glycyrrhizin administered intravenously might bind to hepatocytes at the concentration at which glycyrrhizin could modify the expression of HBV-related antigens on the hepatocytes and suppress sialylation of HBsAg."
PMID: 8783808 (Toyama, Japan)

Article 2: "... Glycyrrhizin suppressed the secretion of HBsAg and accumulated it dose-dependently in ... cells. Its action was further analyzed and determined in the HBsAg-expression system using the varicella-zoster virus. (It) suppressed the secretion of HBsAg, resulting in its accumulation in the cytoplasmic vacuoles in the Golgi apparatus area. HBsAg labeled with 35S-methionine and cysteine accumulated in the cells and its secretion was suppressed dose-dependently in glycyrrhizin-treated culture. The secreted HBsAg was modified by N-linked and O-linked glycans but its sialylation was inhibited dose-dependently by glycyrrhizin. ..."
PMID: 7814808 (Toyama, Japan)

Herpes Simplex, Other Viruses and Licorice Root Extract

Article 1: "Screening investigations in antiviral action of plant extracts have revealed that a component of Glycyrrhiza glabra roots, found to be glycyrrhizic acid, is active against viruses. We report here that this drug inhibits growth and cytopathology of several unrelated DNA and RNA viruses, while not affecting cell activity and ability to replicate. In addition, glycyrrhizic acid inactivates herpes simplex virus particles irreversibly."
PMID: 233133 (1979)

Old Herbs - New Science

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Licorice Root Extract

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Spanish Sage

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Vineatrol (from Grapevine shoots)

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Withanolide (from Ashwagandha)

Zerumbone (from Ginger)
This website acknowledges Pubmed ( as source for medical research abstracts.

These statements have not been evaluated by the FDA. These products are not intended to diagnose, treat, cure, or prevent any disease. Pregnant or lactating women, diabetics, hypoglycemics, and people with known medical conditions and/or taking medicines should consult with a licensed physician and/or pharmacist prior to taking dietary supplements.
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