Elderberry is a popular natural product and remedy used to treat viral infections like influenza (the flu), colds and in recent years, COVID-19. Touted for its immune-boosting properties, and seemingly available in every dosage form from syrups to gummies, elderberry has many enthusiasts, and the billion-dollar market is forecast to continue to grow. With cold and flu season (in the northern hemisphere) approaching quickly, I wanted to refresh my understanding of the evidence supporting this widely marketed remedy. New trials continue to be published – but are the compelling enough to warrant a recommendation?
Elderberry is the dark purple fruit of the European or Black elder, a deciduous tree native to Europe, but also found in North America. The tree produces both elderberries and elderflowers, used in food, beverages, and traditional medicine. Historically, elderberries have been used as folk remedies to treat colds and flu, but they are also used as a diuretic, laxative, and for “stimulating the immune system”. There are a number of potentially active ingredients in elderberry, so it is plausible that elderberry may have biological and medicinal effects. For this review, I focused on evidence for treatments of respiratory infections.
Elderberry extract may inhibit the replication of certain viruses, which fuels much of the marketing. Of course, inhibiting viral replication is not difficult to do in a test tube. Supportive trials published to date have had mixed results. Taking elderberry extract syrup (Sambucol)) 15 mL four times daily for 5 days may improve symptoms such as aches, cough, and nasal congestion about 4 days earlier than control groups, and reduce the need for additional medications. However, in a study involving children and adults aged 5 and older, including those with high-risk conditions, taking Sambucol for 5 days did not significantly shorten the time to complete symptom resolution compared to placebo.
A randomized, double-blind, placebo-controlled trial conducted from January 2018 to April 2019 and published in 2020 aimed to determine if elderberry extract reduces the duration and severity of influenza. The study included 87 patients aged 5 and older with confirmed influenza, who were treated with either elderberry extract or placebo for 5 days. Patients were permitted to choose to also receive oseltamivir (Tamiflu). The primary outcome was the number of days until symptoms were mild or none, and secondary outcomes included total symptom resolution. The results: no significant difference in symptom improvement between the elderberry and placebo groups, with elderberry showing no benefit in reducing flu duration or severity. In fact, post hoc analysis suggested that elderberry alone (i.e., without oseltamivir) may have prolonged symptoms compared to placebo by about two days.
In colds, a 2016 randomized, double-blind, placebo-controlled trial looked at air travel overseas using a standardized elderberry extract. While the number of cold episodes between the placebo and elderberry groups was similar between the two groups participants in the placebo group experienced significantly longer cold durations and more severe symptoms. The authors conclude that elderberry extract may reduce the duration and severity of colds during air travel. As this is a single trial and not replicated, it’s not terribly convincing.
There is no evidence to suggest that elderberry is effective against COVID-19 infections. The FDA and FTC and Federal Trade Commission have taken action against companies that marketed products with claims of effectiveness for COVID-19.
Safety Summary
Elderberry is rated by the Natural Database as likely safe when consumed orally, in amounts typically found in foods, and it holds Generally Recognized As Safe (GRAS) status in the US. It is considered possibly safe when elderberry fruit extract is used short-term. Specific products like Sambucol and BerryPharma have been used safely for up to 5 and 15 days, respectively, while ViraBLOC lozenges are safe for up to 2 days. Consuming unripe or uncooked elderberries, leaves, or stems is considered possibly unsafe due to cyanide-producing chemicals, which can cause serious toxicity. Cooking eliminates this toxin. In children, elderberry is likely safe in food amounts and possibly safe for up to 3 days, but unripe or uncooked elderberries should be avoided. During pregnancy and lactation, elderberry is likely safe in food amounts, but there is insufficient data to ensure its safety when used as a dietary supplement or medicinally. Larger doses should be avoided. There is also the ongoing concern about accuracy of supplement labels (and product contents) which increases the risk to the pregnant/breast feeding.
Don’t skip your flu or COVID-19 shot this fall
Very weak data suggest that elderberry may offer some benefit for colds and flu, but it’s also refuted with conflicting evidence that is more compelling. I don’t recommend elderberry, but it has a reasonable safety profile for most adults. If people really want to self-medicate with something, I warn them that it may not be helpful and there’s a suggestion it could actually be harmful.