top of page

Glycyrrhizin from licorice inhibits SARS-coronavirus entry and replication (in vitro)

Updated: Feb 26, 2020

Severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV): SARS is one of the most severe CoV infections, occasiontally causing a “systemic” influenza-like illness that can lead to respiratory insufficiency. The first outbreak of SARS-CoV was reported from the Guangdong province of China in February 2003 before spreading to 30 countries, 8000 cases, resulting in 774 deaths (ie, slightly less than 10% fatality rate among estimated/reported cases). According to the US CDC[1], “The outbreak lasted approximately six months…before it was stopped in July 2003." Diagnosis is clinical; medical treatment is supportive and nonspecific.[2]

Vitamin C and SARS coronavirus (J Antimicrob Chemother 2003 Dec[3]): “Placebo-controlled trials have shown quite consistently that the duration and severity of common cold episodes are reduced in the vitamin C groups, indicating that viral respiratory infections in humans are affected by vitamin C levels. … The possibility that vitamin C affects severe viral respiratory tract infections would seem to warrant further study, especially in light of the recent SARS epidemic.”

Perspective from DrV: Several human clinical trials have shown benefit to supplemental ascorbate orally administered at 2 grams three times per day for a total of 6 grams per day; except in patients with iron overload, this level of ascorbate supplementation is safe and can provide numerous benefits.

Glycyrrhizin from licorice inhibits entry and replication of SARS-associated coronavirus in vitro (Lancet 2003 Jun[4]): “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. Our findings suggest that glycyrrhizin should be assessed for treatment of SARS.” The authors also noted that in addition to inhibiting viral replication, the licorice extract glycyrrhizin also inhibits adsorption/binding and penetration of the virus, which are early and essential steps in any viral infection.

Perspective from DrV: Licorice has been used medicially for thousands of years, often at doses that are considered therapeutic by modern standards; licorice directly inhibits many different DNA and RNA viruses while also stimulating nonspecific immune defenses. In addition to its broad antiviral activity and immune stimulating benefits, glycyrrhizic acid appears to directly bind herpes virus particles resulting in their irreversible inactivation; as originally stated in a classic 1979 paper, "glycyrrhizic acid inactivates herpes simplex virus particles irreversibly."[5]

  1. "Severe Acute Respiratory Syndrome (SARS) was first discovered in Asia in February 2003. The outbreak lasted approximately six months as the disease spread to more than two dozen countries in North America, South America, Europe, and Asia before it was stopped in July 2003." CDC SARS Response Timeline. Accessed 2020 Feb 18.

  2. Tesini BL. Coronaviruses and Acute Respiratory Syndromes (MERS and SARS). The Merck Mannual Professional Edition. Last full review/revision 2018.

  3. J Antimicrob Chemother. 2003 Dec;52(6):1049-50 PMID:14613951 DOI:10.1093/jac/dkh002

  4. Lancet. 2003 Jun 14;361(9374):2045-6

  5. Nature. 1979 Oct 25;281(5733):689-90

  6. For more details, see our main page on antiviral nutrition:

  7. Download the digital ebook Antiviral Nutrition:

  8. Order the full-color paper book Antiviral Strategies and Immune Nutrition:

792 views0 comments


bottom of page