Deworming (sometimes known as worming, drenching or "dehelmintization") is the giving of an anthelmintic drug (a wormer, dewormer, or drench) to a human or animal to rid them of helminths parasites, such as roundworm, flukes and tapeworm. Purge dewormers for use in livestock can be formulated as a feed supplement that is eaten, a paste or gel that is deposited at the back of the animal's mouth, a liquid drench given orally, an injectable, or as a pour-on which can be applied to the animal's topline. In dogs and cats, purge dewormers come in many forms including a granular form to be added to food, pill form, chew tablets, and liquid suspensions.
Horses are most often dewormed with a paste or gel placed on the back of the animal's mouth via a dosing syringe; feed dewormers are also used, both single-dose varieties and in a daily, "continuous" feed form. Deworming (drenching) a sheep is usually done with a specific drenching gun that squirts an anthelmintic into the sheep's throat.
Mass deworming campaigns of school children have been used both as a preventive as well as a treatment method for helminthiasis which includes soil transmitted helminthiasis in children. Children can be treated by administering for example mebendazole and albendazole. The cost is relatively low. According to the World Health Organization (WHO), over 870 million children (half of the children in the world) are at risk of parasitic worm infection. Worm infections interfere with nutrient uptake; can lead to anemia, malnourishment and impaired mental and physical development; and pose a serious threat to children's health, education, and productivity. Infected children are often too sick or tired to concentrate at school, or to attend at all.
- "Soil Transmitted Helminths". WHO. Retrieved 28 July 2015.
- Miguel, Edward; et al. (May 2015). "Worms at work: Long-run impacts of a child health investment" (PDF). Working Paper. Retrieved 28 July 2015.