Elderberry (Sambucus nigra) is the dark purple berry from the European elder tree. It has a long history of use for cold and flu. Elderberry is a popular ingredient in supplements. It might affect the immune system, and also seems to have activity against viruses, including the flu.

The genus Sambucus includes many species and subspecies of elderberry. Often colloquially, and sometimes in marketing, the Sambucus nigra ssp. nigra and Sambucus nigra canadensis are referred to as “Black” elderberry and Sambucus nigra ssp. cerulea is known as “Blue” elderberry.

The flower and the berries are also used in herbal medicine. Tea made from the flowers is used to reduce inflammation or as a diuretic. Other medicinal applications such as treating sinusitis, and standardized preparations containing extracts or juice of elderberries have been shown to reduce flu symptoms.

Because elderberry may stimulate the immune system, it could interfere with medications taken to suppress the immune system. These medications include corticosteroids (prednisone) and medications used to treat autoimmune diseases. People with organ transplants should also avoid elderberry.