I placed a round bullseye magnet on a nurse's knee bruise following a ski injury. Most people report warmth and gentle tingling under the magnets. Europeans have measured increased blood flow. Others have seen this on thermograms too. They affect some chemical processes within and between cells.
Chemists use sensitive magnetic equipment to measure simple and complex molecules.
Researchers at Harvard found that salt water passes a membrane quicker with a magetic field. They can affect nerve signals. High strength magnets can cause anesthesia, through a principle in physics called the Hall effect. Magnets can stop epileptic seizures. They are also used to study and map nerve structures deep in the brain, normally only accessible during brain surgery.