IsonaRif Side Effects
Generic Name: isoniazid / rifampin
Note: This page contains information about the side effects of isoniazid / rifampin. Some of the dosage forms included on this document may not apply to the brand name IsonaRif.
For the Consumer
Applies to isoniazid / rifampin: oral capsule, oral tablet
In addition to its needed effects, some unwanted effects may be caused by isoniazid / rifampin. In the event that any of these side effects do occur, they may require medical attention.
You should check with your doctor immediately if any of these side effects occur when taking isoniazid / rifampin:More common:
- Clumsiness or unsteadiness
- dark urine
- loss of appetite
- nausea and vomiting
- numbness, tingling, burning, or pain in hands and feet
- unusual tiredness or weakness
- yellow eyes or skin
- difficult breathing
- muscle and bone pain
- skin rash and redness
- Bloody or cloudy urine
- blurred vision or loss of vision, with or without eye pain
- convulsions (seizures)
- greatly decreased frequency of urination or amount of urine
- mood or mental changes
- sore throat
- unusual bleeding or bruising
Some of the side effects that can occur with isoniazid / rifampin may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:More common:
- stomach pain or upset
- Sore mouth or tongue
This medicine commonly causes reddish-orange to reddish-brown discoloration of urine, stool, saliva, sputum, sweat, and tears. This side effect does not usually require medical attention.
Dark urine and yellowing of the eyes or skin (signs of liver problems) are more likely to occur in patients 50 years of age and older.
For Healthcare Professionals
Applies to isoniazid / rifampin: oral capsule
The most common side effects reported with isoniazid were those affecting the nervous system and the liver.[Ref]
Hepatic side effects have been reported frequently with isoniazid and have included elevated serum transaminases (SGOT, SGPT), bilirubinemia, bilirubinuria, jaundice, and occasionally severe and sometimes fatal hepatitis. Transient liver function test abnormalities (such as elevated serum bilirubin, alkaline phosphatase, serum transaminases) and, rarely, hepatitis or a shocklike syndrome (with liver involvement and abnormal liver function tests) have been reported with rifampin use. Rarely, fulminant hepatitis (i.e., acute hepatitis with hepatic encephalopathy) has been reported in patients treated with isoniazid-rifampin.[Ref]
Prodromal symptoms are often observed with isoniazid-associated liver reactions and usually include anorexia, nausea, vomiting, fatigue, malaise, and weakness. Mild and transient elevation of serum transaminase levels occurs in 10% to 20% of patients taking isoniazid. The abnormality usually occurs in the first 4 to 6 months of treatment but can occur at any time during therapy. Enzyme levels usually return to normal even with treatment continuation; however, progressive liver damage occurs in some cases. Isoniazid should be discontinued at once if signs or symptoms indicative of liver damage are detected. The frequency of progressive liver damage increases with age. It is rare in patients under 20, but occurs in up to 2.3% of patients over 50 years of age.[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]
Nervous system side effects have been reported frequently with isoniazid and have included peripheral neuropathy and paresthesias. Convulsions and toxic encephalopathy have rarely been reported with standard isoniazid doses. Headache, drowsiness, fatigue, ataxia, dizziness, pain in extremities, and generalized numbness have been reported with rifampin use.[Ref]
Renal hypersensitivity reactions usually occur during intermittent treatment or in patients resuming treatment following intentional or accidental interruption of the daily regimen. These reactions are reversible when rifampin is discontinued and appropriate therapy started.[Ref]
Renal side effects associated with rifampin have included elevations in blood urea nitrogen. Hemolysis, hemoglobinuria, hematuria, interstitial nephritis, renal insufficiency, and acute renal failure have rarely been reported and are usually considered hypersensitivity reactions.[Ref]
Thrombocytopenia has occurred with concomitant rifampin and ethambutol use according to a twice weekly dose schedule and in high doses.[Ref]
Hematologic side effects associated with isoniazid have included agranulocytosis, anemia (hemolytic, sideroblastic, or aplastic), thrombocytopenia, and eosinophilia. Thrombocytopenia, leukopenia, hemolytic anemia, eosinophilia, decreased hemoglobin, and agranulocytosis (rare) have been reported with rifampin use.[Ref]
Hypersensitivity side effects associated with isoniazid have included fever, skin eruptions (morbilliform, maculopapular, purpuric, or exfoliative), lymphadenopathy, and vasculitis. Occasionally pruritus, urticaria, rash, pemphigoid reaction, eosinophilia, sore mouth, sore tongue, exudative conjunctivitis, and, rarely, renal hypersensitivity reactions have been reported with rifampin use.[Ref]
Metabolic side effects associated with isoniazid have included pyridoxine deficiency, pellagra, hyperglycemia, and metabolic acidosis. Elevated serum uric acid has been reported with rifampin.[Ref]
Gastrointestinal side effects associated with isoniazid have included nausea, vomiting, and epigastric distress. Heartburn, epigastric distress, anorexia, nausea, vomiting, gas, cramps, diarrhea, and a red-orange discoloration of feces, saliva, and sputum have been reported with rifampin use.[Ref]
Psychiatric side effects associated with isoniazid are infrequent with standard doses and have included memory impairment and toxic psychosis. Inability to concentrate and mental confusion have been reported with rifampin use.[Ref]
Ocular side effects associated with isoniazid are infrequent with standard doses and have included optic neuritis and atrophy. Visual disturbances and a red-orange discoloration of tears have been reported with rifampin use.[Ref]
Other side effects associated with isoniazid have included systemic lupus erythematosus-like syndrome. Fever and a red-orange discoloration of sweat have been reported with rifampin use.[Ref]
Musculoskeletal side effects associated with isoniazid have included rheumatic syndrome. Muscular weakness has been reported with rifampin use.[Ref]
Endocrine side effects associated with isoniazid have included gynecomastia.[Ref]
Genitourinary side effects associated with rifampin have included menstrual disturbances and a red-orange discoloration of urine.[Ref]
Immunologic side effects associated with rifampin have included an immunosuppressive effect in some animal experiments; however, available human data indicate that this has no clinical significance.[Ref]
1. "Product Information. Rifamate (isoniazid-rifampin)." Aventis Pharmaceuticals, Kansas City, MO.
2. Pessayre D, Bentata M, Degott C, et al. "Isoniazid-rifampin fulminant hepatitis." Gastroenterology 72 (1977): 284-9
Not all side effects for IsonaRif may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.
More about IsonaRif (isoniazid / rifampin)
- Other brands: Rifamate
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