Elderberries have been used for centuries for their medicinal qualities. In fact, way back in 400 B.C., Hippocrates, known as the “Father of Medicine,” called the elder tree his medicine chest. Sales of elderberry soared to $276 million in 2020, five times the sales figure in 2018, due to COVID-19 and elderberry’s reputation for its disease-fighting and immune-boosting properties.

Elderberry extract prevents oxidative stress, stimulates the immune system, and can even lower blood pressure and blood sugar. According to Nutritional Outlook, supplementation with elderberry reduces the severity of symptoms in upper respiratory tract infections like colds and flu.

A study published in the Journal of Functional Foods found that elderberry extract is an effective way to block viruses from entering and attaching to healthy cells. For the study, researchers applied a serum made from elderberries directly onto cells before, during, and after they had been infected with the influenza virus.

“We found that the serum had a direct antiviral effect against the flu virus,” said lead researcher Dr. Golnoosh Torabian. Experts say that elderberry contains bioactive ingredients such as anthocyanin flavonoids that appear to block viruses from binding to cells.

You can consume the fruit itself to derive health benefits or purchase supplements in the form of gummies, lozenges, syrups, and teas, says Verywell Health. The European elder or black elderberry (Sambucus nigra) is the species most often use in supplements.

Besides its scientifically proven benefits in preventing and treating colds and flu, elderberries can help clear your body of free radicals that damage cells and cause disease. The fruit also has anti-inflammatory properties, thanks to the anthocyanins it contains. Elderberry seems to slow down the inflammatory response, which may reduce swelling and the pain it can cause. In fact, topical elderberry tinctures and salves have been used in folk medicine to treat dental pain, cuts, bruises, and burns.

Eating too much elderberry fruit can cause diarrhea, stomach pain, and abdominal cramping. The berries should always be thoroughly cooked before they are consumed, warns Verywell Health. Check with your healthcare professional before taking elderberry because it interacts with certain drugs such as corticosteroids and some medications used to treat arthritis. Also, it is not recommended for certain groups of people, such as children, those who are pregnant and women who are breastfeeding.

Cold and flu treatment should begin no later than 48 hours after the first cold and flu symptoms appear. Since elderberry amounts vary according to the product, check package labels carefully for the correct dosage. Elderberry-based medications are classified as dietary supplements by the Food and Drug Administration. They are not sold or marketed as a treatment for any medical condition.

Since supplements aren’t required to undergo rigorous testing, the quality of elderberry extract can vary greatly from product to product. Look for supplements that have been certified by an independent body such as U.S. Pharmacopeia (USP), NSF International, or ConsumerLab.

These groups do no evaluate supplements for their effectiveness, but they make sure the products are not contaminated and contain the ingredients claimed on the label.