Ergot alkaloids are a group of compounds derived from the Claviceps purpurea fungus, which infects cereal grains like rye. These alkaloids have various effects on the human body, including vasoconstriction and stimulation of smooth muscle. They are known for their historical use in medicine, particularly in treating migraines and inducing labor. In addition to their medicinal properties, ergot alkaloids can be toxic in high doses, leading to a condition known as ergotism. This condition can cause symptoms such as hallucinations, convulsions, and severe vasoconstriction. Due to their potent effects, ergot alkaloids are carefully regulated in pharmaceutical applications.