At the recommended dosage, Comazole is usually well tolerated. Of the reported adverse effects, most are mild and comprised nausea (with or without vomiting) and skin rashes. As with great variety of other drugs, Comazole has isolated cases been associated with the Steven -Johnson syndromes.
Haematological changes have been reported, the majority being mild, asymptomatic, and reversible on withdrawal of the drug. The changes mainly took the form of leukopenia, neutropenia and thrombocytopenia. Very rarely, agranulocytosis, megaloblastic anaemia and purpura occurred. Although trimethoprim and sulphamethoxazole are excreted in breast milk, administration of this combination to nursing mothers represents a negligible risk to the infants.
The most common side effects are gastrointestinal disturbances (nausea, vomiting, anorexia) and also skin rashes. Also includes glostitis, pancreatitis, stomatitis, diarrhoea and rarely cases of pseudomonas enterocolitis.