Side effects are associated with the degree of plasma concentration of sulfapyridine, especially in people with slow acetylation. More often, side effects are observed in patients with rheumatoid arthritis.
From the central and peripheral nervous system: headache, peripheral neuropathy, dizziness, sleep disturbance, hallucinations, ataxia, convulsions, depression, aseptic meningitis.
From the gastrointestinal tract: nausea, vomiting, diarrhea, decreased appetite, pancreatitis, stomatitis, abdominal pain, drug-induced hepatitis.
On the part of the organs of hematopoiesis: macrocytosis, leukopenia, neutropenia, megaloblastic anemia, hemolytic anemia, hemolytic anemia due to enzymatic disorders - with unstable hemoglobin molecules (Heinz-Ehrlich body), methemoglobinemia, agranulocytosis, thrombocytopenia, aplastic anemia, hypoprothrombinemia.
From the genitourinary system: proteinuria, hematuria, crystalluria, nephrotic syndrome, transient oligospermia and male infertility.
From the respiratory system: shortness of breath, cough, interstitial pneumonitis, fibrosing alveolitis, infiltrates in the lung tissue.
From the sense organs: noise in ears.
Laboratory data: hyperbilirubinemia, increased activity of alkaline phosphatase, "hepatic" transaminases.
Allergic reactions: generalized skin rash, urticaria, erythema, pruritus, exfoliative dermatitis, photosensitivity, malignant exudative erythema (Stevens-Johnson syndrome), toxic epidermal necrolysis (Lyell's syndrome), fever, lymphadenopathy, serum sickness, periorbital edema, eosinophilia, periarteritis nodosa, anaphylactic shock.
Other: hyperthermia, parotitis, possibly staining urine, skin or soft contact lenses in a yellow-orange color.