This potent anti-viral formula stimulates the immune system. Elderberry is one of the most effective herbs for preventing and treating upper respiratory infections, constipation, and fever. Elderberry contains substances called Sambucus nigra agglutinins (SNAs) that can “lock” receptor sites on certain strains of flu viruses. These keep the viruses from infecting human cells. A clinical trial of elderberry found that it cured 90% of flu infections within 72 hours. In the same trial, patients receiving a placebo needed six days to recover. Elderberry also relieves nasal congestion, fever, and sore throat. Elder flowers treat colds, influenza (flu), swine flu, bronchitis, and constipation. It relieves allergy and asthma symptoms, and detoxifies the body and fights free radicals.