Niclosamide (trade name Niclocide) is a teniacide in the anthelmintic family especially effective against cestodes that infect humans and many other animals. It is a salicylanilide compound (5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydrobenzamide) also used as a piscicide. While antihelmintics are a drug family used to treat worm infections, niclosamide is used specifically to treat tapeworms and is not effective against other worms such as pinworms or roundworms. It is a chewable tablet taken orally, dosage depending on type of worm and patient's age and/or weight. It is not usually considered the drug of choice for treating cestode infection in humans or animals because of its side effects, though it remains highly effective and is generally inexpensive. Along with oxyclozanide, another tapeworm drug, it has been recently found to display "strong in vivo and in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA)". It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system.