The bark and leaves are very effective to break and bring down minor fevers and colic.

The bark is most helpful to treat rheumatism, arthritis and gout, as well as diarrhea and dysentery, headache and neuralgia. 

The pain relieving action as analgesic is due to the inhibition of prostaglandin synthesis by the salicin derivatives, which cause sensitization of peripheral pain receptors, and "natural aspirin" from the willow bark seems to have far less side effects than the synthetic aspirin made by pharmaceutical companies.