Elderberry belongs to a family of flowering shrubs known as Sambucus or Elder. They are native to Europe but have become naturalized in many parts of the world including the United States. Cultivated for medicinal and food purposes, the fruit is used to produce jams, syrups, and wine. Elderberry flowers and fruit are incorporated in remedies to reduce cold and flu symptoms, for inflammation and respiratory diseases ^{(1) (2) (3)}, and to relieve constipation ⁽⁴⁾. The berries are a rich source of anthocyanins and other phenolics and nutrients ⁽²⁾. Several species of Sambucus produce elderberries with similar chemical compositions including American Elder (Sambucus canadensis) and Blue Elder (Sambucus caerulea) ⁽¹⁾, but European Elder (Sambucus nigra) is the type most studied and used in supplements.

In vitro studies demonstrate that elderberries possess antiviral ⁽⁵⁾, antibacterial ⁽³⁾, antidiabetic ⁽⁶⁾, immunomodulatory ⁽⁷⁾, antioxidant, anti-inflammatory, and chemopreventive properties ^{(1) (2) (8)}, although inhibition of cancer cell growth was shown to be weak ⁽⁹⁾. Flavonoids and proanthocyanidins were shown to block HIV1 infection, and may have additive effects with existing AIDS drugs such as enfuvirtide ⁽¹⁰⁾. Elderberry also conferred protective effects against oxidative stressors in endothelial cells ⁽⁸⁾. However, it did not demonstrate vasoprotective effects ⁽¹¹⁾, and randomized trials found it ineffective in improving cardiovascular disease biomarkers ⁽¹²⁾ or for improving cholesterol levels ⁽¹³⁾. Small studies found elderberry to be safe and effective in a preparation for chronic constipation ⁽⁴⁾ and in reducing episodes of tonsillitis in children ⁽³³⁾. It may also help reduce symptoms of influenza ^{(14) (28) (34) (35)}, but larger studies are needed to confirm these findings ⁽³²⁾.

Unsubstantiated claims that elderberry prevents or treats various diseases including AIDS, diabetes, flu ⁽¹⁵⁾ and COVID-19 ^(36) (37) have been halted by the FDA. This is particularly important as patients may forego or avoid legitimate treatments.