Levamisol

Levamisol, sometimes spelled levamisole, is a synthetic drug with immunomodulatory and anthelmintic properties. It belongs to the class of imidazoline derivatives and has been used in human medicine for treating certain parasitic infections as well as for cancer immunotherapy in select settings. It is available in oral tablet form and, in some countries, as an injectable preparation.

Medical uses and indications vary by country. As an antiparasitic agent, levamisole has been used to treat helminth infections such as ascariasis, trichuriasis, hookworm, and strongyloidiasis, often in combination with other anthelmintics or under specific regional guidelines. In oncology, it has been employed as an adjuvant immunotherapy for colorectal cancer in the past, typically in combination with fluoropyrimidines; however, its role has diminished in many guidelines as newer regimens emerged. Levamisole is not a first-line treatment for most conditions in many regions today.

Mechanism of action centers on immune modulation. Levamisole stimulates T-lymphocyte activity and enhances cell-mediated immunity, with effects on macrophages and cytokine production that can promote anti-tumor and anti-infective responses. The precise mechanisms, especially in cancer, are not fully understood.

Adverse effects range from mild to serious. Common reactions include fever, fatigue, nausea, abdominal pain, and skin rash. More serious but less common events include neutropenia or agranulocytosis, vasculitis, liver inflammation, and other immune-mediated phenomena. It may interact with vaccines and other immunomodulators, and its use is contraindicated in certain autoimmune conditions or during some infections.

Levamisole has also appeared as a contaminant in illicit cocaine, where it has been linked to neutropenia and vasculitic syndromes.