Conventionally dried nettle leaf is a tonifier. When it is freeze dried with care additional properties are preserved which support the respiratory system. Freeze-drying preserves the key constituents of nettles stinging hairs histamine 5-hydroxytryptamine Acetylcholine and formic acid inhibits the bodys production of arachidonic acid and leukotrienes. In comparison with most competing products that give300 mg this delivers 420 mg per tablet. Freeze-dried Stinging Nettles are formulated to support the sinus & Respiratory system. Helps as a respiratory support for stressful seasonal change.