Santonin, a natural compound, is a sesquiterpene lactone. It is known as an anthelmintic drug which was used in the past (19th - early 20th centuries) mainly to treat different kinds of intestinal worms such as roundworm or ascaris lumbricoides except the tapeworm. It was also indicated for use in retention of urine and nocturnal enuresis from atony, urethral irritation with pain at uterine disorders, retention of urine in fevers, deficient spinal innervation, as evidenced by impaired respiration and tympanitis, vesical tenesmus and strangury, retention of urine from the use of opiates. Santonin was formerly listed in U.S. and British pharmacopoeia but due to the severe side effects and the development of many safer deworming drugsa it is no longer registered as a drug in most countries. Originally isolated from the poisons plant Artemisia maritima, santonin is itself a toxic compound. It is the anhydride of santonic acid, which is a derivative of dimethyl-naphtalene. It dissolves in alkalies with formation of salts of this acid. In acetic acid solution, when exposed to sunlight for about a month, santonin is converted into photosantonic acid. Santonin was found to have significant anti-inflammatory activity on acute inflammatory processes and as shown in vitro can activate pregnane X receptors and constitutive androstane receptors and subsequently increases the expression of drug-metabolizing enzymes.