Elderberry has been used for centuries as a tonic for colds, flu and sinus infections.  It also contains viburnic acid, a compound that encourages perspiration and helps to detox the body.  It is believed that elderberry can help reduce fever, purify the blood, and cleanse the body of pathogens.  All the parts that make up the elder flower have been used medicinally throughout history including the stems, leaves, berries and flowers.  Elderberry extract has proved to be specifically active against the influenza virus by blocking replication very effectively.