The Side Effects of Drugs Annuals form a series of volumes in which the adverse effects of drugs and adverse reactions to them are surveyed. The series supplements the contents of Meyler's Side Effects of Drugs: the International Encyclopedia of Adverse Drug Reactions and Interactions. This review of the 2011 publications on antihelminthic drugs covers the benzimidazoles albendazole and benznidazole, ivermectin, levamisole, and praziquantel. Levamisole has become a very common adulterant of street cocaine and can cause a wide range of adverse reactions, such as neutropenia and agranulocytosis, vasculitis and/or vasculopathy, with a particular predilection for the ears, causing necrosis of the pinnae, skin necrosis, purpuric eruptions, often retiform, antiphospholipid antibody syndrome, and microvascular thrombosis; in some cases combinations of two or more of these reactions occur. © 2014 Elsevier B.V.