Decreased appetite, excessive salivation, nausea, vomiting, flatulence, abdominal pain, diarrhea or constipation, hyperbilirubinemia, increased activity of "hepatic" transaminases, proteinuria, hematuria, crystalluria.
Rarely - thrombocytopenia, leukopenia (up to agranulocytosis), drug-induced hepatitis, incl. with lethal outcome, in 12-deficient megaloblastic anemia.
Allergic reactions - fever, dermatitis (urticaria, purpura, enanthema), eosinophilia, arthralgia, bronchospasm.
With prolonged use in high doses - hypothyroidism, goiter, myxedema.