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Isoniazid / rifampin Side Effects

Medically reviewed by Last updated on Apr 29, 2024.

Applies to isoniazid / rifampin: oral capsule.


  • This drug may cause very bad and sometimes deadly liver problems like hepatitis. Call your doctor right away if you have signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • The chance of liver problems is higher the older you are. The chance may also be raised by drinking alcohol every day, long-term liver problems, or injection drug use. The chance of liver problems may also be raised in women, mainly women who are black or Hispanic or who have just had a baby. Most of the time, liver problems caused by this drug happen within the first 3 months of care, but they can happen at any time. Most of the time, liver function has gone back to normal but sometimes it has not. Blood work will need to be done before starting this drug and while taking it. If you have questions, talk with the doctor.
  • If you have active liver disease, talk with your doctor. This drug may not be right for you.

Serious side effects

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

Other side effects

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

For Healthcare Professionals

Applies to isoniazid / rifampin: oral capsule.


Doses greater than 600 mg of rifampin given once or twice weekly have resulted in a higher incidence of adverse reactions, including the "flu syndrome" (fever, chills, malaise); hematopoietic reactions (leukopenia, thrombocytopenia, acute hemolytic anemia); shortness of breath; shock; anaphylaxis; renal failure; and cutaneous, gastrointestinal, and hepatic reactions.[Ref]


Frequency not reported: Vasculitis


Frequency not reported: Flushing, decreased blood pressure[Ref]


Frequency not reported: Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome, Stevens-Johnson syndrome, Toxic Epidermal Necrolysis (TEN), rash


Frequency not reported: Acne, exfoliative dermatitis, pemphigus


Frequency not reported: Erythema multiforme, skin reaction, pruritus, pruritic rash, urticaria, allergic dermatitis, pemphigoid, sweat discoloration, cutaneous reactions[Ref]



Frequency not reported: Gynecomastia, hyperglycemia


Rare (less than 0.1%): Adrenal insufficiency

Frequency not reported: Menstrual disorder/disturbances[Ref]


Frequency not reported: Nausea, vomiting, epigastric distress, diarrhea


Frequency not reported: Constipation, dry mouth, pancreatitis


Frequency not reported: Gastrointestinal disorder, abdominal discomfort, heartburn, flatulence, cramps, pseudomembranous colitis, sore mouth, sore tongue[Ref]


Frequency not reported: Thrombocytopenia, eosinophilia, agranulocytosis, hemolytic anemia


Frequency not reported: Anemia, aplastic anemia, lymphadenopathy


Uncommon (0.1% to 1%): Leukopenia

Rare (less than 0.1%): Disseminated intravascular coagulation

Frequency not reported: Decreased hemoglobin[Ref]


Frequency not reported: Hepatitis, elevated serum transaminases (SGOT, SGPT), bilirubinemia, bilirubinuria, jaundice


Common (1% to 10%): Elevated alkaline phosphatase

Rare (less than 0.1%): Abnormal liver function, shock-like syndrome with hepatic involvement

Frequency not reported: Hyperbilirubinemia[Ref]



Rare (less than 0.1%): Anaphylaxis[Ref]



Frequency not reported: Pellagra, pyridoxine deficiency, metabolic acidosis


Frequency not reported: Decreased appetite, anorexia[Ref]



Frequency not reported: Systemic lupus erythematosus-like syndrome, rheumatic syndrome


Rare (less than 0.1%): Myopathy

Frequency not reported: Muscle weakness, bone pain[Ref]

Nervous system


Common (1% to 10%): Peripheral neuropathy

Uncommon (0.1% to 1%): Convulsions, toxic encephalopathy, optic neuritis and atrophy, memory impairment

Frequency not reported: Vertigo, polyneuritis (presenting as paresthesia, muscle weakness, loss of tendon reflexes)


Frequency not reported: Headache, drowsiness, cerebral hemorrhage, ataxia, dizziness, inability to concentrate, muscular weakness, pains in extremities, generalized numbness[Ref]

Peripheral neuropathy associated with isoniazid is dose-dependent, most often occurs in malnourished patients and in patients predisposed to neuritis (such as alcoholics and diabetics), and generally follows paresthesias of the hands and feet. The rate is higher in slow acetylators.[Ref]



Frequency not reported: Tear discoloration, visual disturbances, conjunctivitis[Ref]


Frequency not reported: Fever


Frequency not reported: Anti-nuclear antibodies


Frequency not reported: Influenza-like syndrome, post-partum hemorrhage, fetal-maternal hemorrhage, porphyria, edema, fatigue, facial edema, edema of the extremities, shock[Ref]



Frequency not reported: Toxic psychosis


Frequency not reported: Psychotic disorder/psychoses, mental confusion, behavioral changes[Ref]



Rare (less than 0.1%): Hemolysis, hemoglobinuria, hematuria, interstitial nephritis, acute tubular necrosis, renal insufficiency, acute renal failure

Frequency not reported: Acute kidney injury, chromaturia, increased blood creatinine, elevated BUN, elevated serum uric acid[Ref]



Frequency not reported: Dyspnea, wheezing, discolored sputum, shortness of breath[Ref]


1. (2001) "Product Information. Rifamate (isoniazid-rifampin)." Aventis Pharmaceuticals

2. Cerner Multum, Inc. "UK Summary of Product Characteristics."

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.