Herbal supplements are dietary supplements that come from plants. People use dietary supplements for many health conditions. Historically, people have used herbal medicines to prevent illness, cure infection, relieve fever, and heal wounds. Herbal medicines can also treat constipation, ease pain, or act as relaxants or stimulants. It is likely that humans have used plants as medicine for as long as we have existed. Archeological excavations dated as early as 60,000 years ago have found remains of medicinal plants, such as opium poppies, ephedra, and cannabis.