Elderberry, sourced from the European black elder tree (Sambucus nigra), is a fruit widely recognized in traditional medicine. For centuries, various parts of the plant have been used as a folk remedy, particularly for symptoms associated with the common cold and influenza. The global health crisis spurred immense public interest in elderberry’s potential application against SARS-CoV-2, the virus that causes COVID-19. This raised questions about whether the historical benefits of elderberry translate into an effective or safe measure for a novel respiratory infection. The effectiveness and safety profile of this supplement must be carefully examined.
Scientific Basis for Elderberry’s Traditional Use
The traditional use of elderberry is rooted in the high concentration of bioactive compounds found within the dark purple fruit. These include polyphenols, such as flavonoids and anthocyanins, which are responsible for the berry’s vibrant color and biological activity. Research has demonstrated that these compounds possess antiviral properties, often studied in relation to the influenza virus.
One proposed mechanism involves elderberry components physically interacting with viral particles. These phytochemicals can inhibit the virus’s ability to attach to host cells or penetrate the cell membrane, effectively blocking the initial stage of infection. Some compounds may also interfere with viral replication later in the cycle, slowing the spread of the virus after the cell has been infected.
Elderberry extracts also exhibit anti-inflammatory effects that may help mitigate respiratory symptoms. The active components modulate the immune system by affecting the release of chemical messengers called cytokines. By influencing these signaling molecules, elderberry may help regulate the body’s inflammatory response, which is a major contributor to discomfort during a respiratory illness.
Elderberry and COVID-19: Clinical Evidence
Despite promising mechanisms observed in laboratory settings against other viruses, definitive clinical evidence for elderberry’s efficacy against COVID-19 outcomes is lacking. Early data suggesting an effect came from in vitro studies on different virus strains or from studies on influenza, which do not directly translate to human benefits against SARS-CoV-2. A few small human clinical trials were initiated during the pandemic, but many were limited in scope or terminated early, providing insufficient data.
The theoretical concern surrounding elderberry use involved the risk of triggering a “cytokine storm.” This reaction is a severe, hyper-inflammatory immune response seen in some severe COVID-19 cases that can damage lung tissue. Because elderberry can stimulate the release of certain cytokines, some hypothesized it could exacerbate this dangerous condition.
Experts note that the scale of cytokine induction by elderberry extract is minimal compared to the surge that occurs during a true cytokine storm. Studies indicate that elderberry may increase these immune messengers by a factor of two to six, while a severe viral storm involves an increase of a thousand times or more. The consensus remains that there is no robust clinical data to support elderberry as a preventative agent or a reliable treatment for reducing the severity, duration, or hospitalization rates associated with COVID-19.
Safety, Dosage, and Regulatory Guidance
The safety of elderberry products depends on proper processing. Raw elderberries, leaves, stems, and bark contain cyanogenic glycosides. When ingested, these compounds metabolize into cyanide, causing nausea, vomiting, or severe diarrhea. Commercial supplements, such as syrups and capsules, are typically made from ripe berries that have been heated. This process effectively neutralizes the toxic compounds.
Dosing for commercially available extracts is generally based on previous studies for influenza or general immune support. Typical amounts may range from 15 milliliters of syrup taken four times per day for a few days, or capsules providing 650 to 1,500 milligrams of extract daily. There is no medically standardized dosage established for the treatment or prevention of COVID-19 due to the lack of clinical trials.
Elderberry’s immune-modulating properties necessitate caution for individuals taking prescription medications. Because the fruit can increase immune system activity, it may counteract the effects of immunosuppressant drugs taken by organ transplant recipients or people with autoimmune conditions. Health organizations, including the National Institutes of Health and the Food and Drug Administration, do not recommend elderberry for the treatment or prevention of COVID-19. The FDA has also issued warning letters to manufacturers who marketed supplements with unproven claims of treating the disease.