Capsule: Nausea, vomiting, dizziness, ataksia, nystagmus, speaking difficulty, tremors, sleeping difficulty, diplopia, constipation, hepatitis, bone marrow depression, lupus systemic erythematosus, Steven-Johnson syndrome, lymphadenopathy, leukopenia, thrombocytopenia, agranulocytosis, megaloblastic anemia due to folic acid deficiency.