Praziquantel (PZQ), sold under the brandname Biltricide among others, is a medication used to treat a number of types of parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is used to treat schistosomiasis, clonorchiasis, opisthorchiasis, tapeworm infections, cysticercosis, echinococcosis, paragonimiasis, fasciolopsiasis, and fasciolosis. It should not be used for worm infections of the eye. It is taken by mouth. Side effects in humans may include poor coordination, abdominal pain, vomiting, headache, and allergic reactions. While it may be used during pregnancy, it is not recommended for use during breastfeeding. Praziquantel is in the anthelmintic class of medications. It works partly by affecting the function of the worm's sucker. Praziquantel was approved for medical use in the United States in 1982. It is on the World Health Organization's List of Essential Medicines. Medical uses Praziquantel is used to treat diseases caused by infection with several types of internal/gastrointestinal, and external parasites, including: Hydatid disease caused by infection of various organs with larval stages of tapeworms of the genus Echinococcus Cysticercosis caused by infection of the brain and/or muscles with the eggs and larvae of the pork tapeworm Taenia solium (though it has been judged less effective than albendazole in treatment of neurocysticercosis) In dogs and cats, whose gastrointestinal tracts are infected with the tapeworms Dipylidium caninum or Taenia taeniaeformis, respectively; praziquantel is also often used in fixed combination with pyrantel embonate against the roundworms (ascarids): Toxocara cati and Toxascaris leonina. Praziquantel is also effective against Echinococcus multilocularis. Schistosomiasis caused by trematodes of the genus Schistosoma: As of 2005, praziquantel is the primary treatment for human schistosomiasis, for which it is usually effective in a single dose. Clonorchiasis brought on by the Chinese liver fluke Clonorchis sinensis Paragonimiasis caused by infection with lung flukes, mostly of the species Paragonimus westermani Fasciolopsiasis caused by intestinal fluke Fasciolopsis buski Side effects The majority of side effects develop due to the release of the contents of the parasites as they are killed and the consequent host immune reaction. The heavier the parasite burden, the heavier and more frequent the side effects normally are. Central nervous system (CNS): Frequently occurring side effects are dizziness, headache, and malaise. Drowsiness, somnolence, fatigue, and vertigo have also been seen. Almost all patients with cerebral cysticercosis experience CNS side effects related to the cell-death of the parasites (headache, worsening of pre-existing neurological problems, seizures,