Adverse reactions reported for individual components are as follows.
Rifampicin: Gastrointestinal: Heartburn, epigastric distress, anorexia, nausea, vomiting, jaundice, flatulence, cramps and diarrhea have been reported.
Hematological: Thrombocytopenia, transient leukopenia, hemolytic anemia and decreased hemoglobin have been observed.
Central Nervous System: Headache, fever, drowsiness, fatigue, ataxia, dizziness, mental confusion, behavioral changes and rarely, myopathy have been reported.
Ocular: Visual disturbances.
Renal: Elevations in blood urea nitrogen and serum uric acid have been reported. On rare occasions, hemolysis, hemoglobinuria, hematuria, interstitial nephritis, renal insufficiency and acute renal failure have been observed.
Cutaneous: These are mild and self-limiting but are not hypersensitivity reactions. They occur in the form of flushing and itching with or without rash.
Hypersensitivity Reactions: These are seen occasionally as pruritus, urticaria, rash, pemphigoid reaction, eosinophilia and conjunctivitis.
Isoniazid: Hepatitis: Severe hepatitis may occur due to isoniazid, which may sometimes be fatal. The risk of developing hepatitis is age-related and increases after the age of 20 years and is maximum at 65 years. This risk is also increased with daily consumption of alcohol. Patients given isoniazid are therefore required to be monitored at regular intervals for serum transaminase levels and for any prodromal symptoms of hepatitis eg, fatigue, weakness, malaise, anorexia, nausea or vomiting.
Peripheral Neuropathy: This is the most common side effect, which is dose related. Occurs more commonly in the patients susceptible to neuropathy eg, malnourished, alcoholics, diabetics.
Gastrointestinal: Nausea, vomiting and epigastric distress.
Hematologic: Agranulocytosis, hemolytic, sideroblastic or aplastic anemia, thrombocytopenia and eosinophilia.
Hypersensitivity Reactions: Fever, skin eruptions, lymphadenopathy and vasculitis.
Metabolic: Pyridoxine deficiency, pellagra, hyperglycemia, metabolic acidosis and gynecomastia.
Miscellaneous: Rheumatic syndrome and systemic lupus erythematosus-like syndrome.