Warning: Willow bark contains salicin, people who are allergic or sensitive to salicylates (such as aspirin) should not use willow bark.  People with asthma, diabetes, gout, gastritis, hemophilia, stomach ulcers, kidney or liver issues or take nonsteroidal anti-inflammatory drugs (NSAIDs) or blood-thinning medication, ask your health care provider before taking willow bark. Children under the age of 18 should not take willow bark.   Do not exceed 6 capsules per day.