Does Noroxin (norfloxacin) cause side effects?

Noroxin (norfloxacin) is a fluoroquinolone antibiotic used to treat a variety of infections such as urinary tract infections (UTIs), gonorrhea, E. coli, and others. 

Noroxin works by blocking DNA gyrase enzyme, which is responsible for production and repair of bacterial DNA. Blocking of DNA gyrase leads to bacteria death and prevents worsening of infection. 

Noroxin treats infections caused by gram-positive and gram-negative bacteria like

Common side effects of Noroxin include

Serious side effects of Noroxin include

Drug interactions of Noroxin include medications like caffeine, clozapine, ropinirole, cyclosporine, theophylline, and tizanidine, because Noroxin can slow down breakdown of these medications in and increase their levels in the body.

  • Noroxin should be separated from aluminum and magnesium containing antacids, sucralfate and multivitamins because they can lower absorption Noroxin and reduce its effectiveness. They should be administered 2 hours before Noroxin.
  • Noroxin should be used with caution with warfarin because Noroxin can increase the risks of bleeding and bruising.
  • Noroxin should be used with caution with medications used for treating abnormal heart beats because it can affect heart rhythm. 

There are no adequate and well-controlled studies of Noroxin in pregnant women. Noroxin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. 

It is unknown if Noroxin enters breast milk; therefore, it is best to be cautious before using it in breastfeeding mothers.

What are the important side effects of Noroxin (norfloxacin)?

Side effects of norfloxacin are

Norfloxacin as well as other antibiotics in the fluoroquinolone class of antibiotics, has been associated with tendinitis and even rupture of tendons, particularly the Achilles tendon.

Many antibiotics, including norfloxacin, can alter the normal bacteria in the colon and encourage overgrowth of a bacterium responsible for the development of inflammation of the colon, (C. difficile caused pseudomembranous colitis).

Patients who develop signs of pseudomembranous colitis after starting norfloxacin (diarrhea, fever, abdominal pain, and possibly shock) should contact their doctor immediately.

Fluoroquinolones have neuromuscular blocking activity and can worsen muscles weakness in individuals with myasthenia gravis. They also worsen low blood glucose levels when combined with sulfonylureas (for example, glyburide [Micronase, Diabeta, Glynase, Prestab]).

Noroxin (norfloxacin) side effects list for healthcare professionals

Single-Dose Studies

In clinical trials involving 82 healthy subjects and 228 patients with gonorrhea, treated with a single dose of norfloxacin, 6.5% reported drug-related adverse experiences. However, the following incidence figures were calculated without reference to drug relationship.

The most common adverse experiences ( > 1.0%) were:

  • dizziness (2.6%),
  • nausea (2.6%),
  • headache (2.0%), and
  • abdominal cramping (1.6%).

Additional reactions (0.3%-1.0%) were:

Laboratory adverse changes considered drug-related were reported in 4.5% of patients/subjects. These laboratory changes were:

  • increased AST (SGOT) (1.6%),
  • decreased WBC (1.3%),
  • decreased platelet count (1.0%),
  • increased urine protein (1.0%),
  • decreased hematocrit and hemoglobin (0.6%), and
  • increased eosinophils (0.6%).

Multiple-Dose Studies

In clinical trials involving 52 healthy subjects and 1980 patients with urinary tract infections or prostatitis treated with multiple doses of norfloxacin, 3.6% reported drug-related adverse experiences. However, the incidence figures below were calculated without reference to drug relationship.

The most common adverse experiences ( > 1.0%) were:

  • nausea (4.2%),
  • headache (2.8%),
  • dizziness (1.7%), and
  • asthenia (1.3%).

Additional reactions (0.3%-1.0%) were:

Less frequent reactions (0.1%-0.2%) included:

Abnormal laboratory values observed in these patients/subjects were:

  • eosinophilia (1.5%),
  • elevation of ALT (SGPT) (1.4%),
  • decreased WBC and/or neutrophil count (1.4%),
  • elevation of AST (SGOT) (1.4%), and
  • increased alkaline phosphatase (1.1%).

Those occurring less frequently included

  • increased BUN,
  • increased LDH,
  • increased serum creatinine,
  • decreased hematocrit, and
  • glycosuria.

Post-Marketing

The most frequently reported adverse reaction in post-marketing experience is rash.

CNS effects characterized as generalized seizures, myoclonus and tremors have been reported with Noroxin. Visual disturbances have been reported with drugs in this class.

The following additional adverse reactions have been reported since the drug was marketed:

Hypersensitivity Reactions

Hypersensitivity reactions have been reported including anaphylactoid reactions, angioedema, dyspnea, vasculitis, urticaria, arthritis, arthralgia and myalgia.

Skin

Toxic epidermal necrolysis, Stevens-Johnson syndrome and erythema multiforme, exfoliative dermatitis, photosensitivity/phototoxicity reactions, leukocytoclastic vasculitis, drug rash with eosinophilia and systemic symptoms (DRESS syndrome).

Gastrointestinal

Pseudomembranous colitis, hepatitis, jaundice including cholestatic jaundice and elevated liver function tests, pancreatitis (rare), stomatitis. The onset of pseudomembranous colitis symptoms may occur during or after antibacterial treatment.

Hepatic

Hepatic failure, including fatal cases.

Cardiovascular

On rare occasions, prolonged QTc interval and ventricular arrhythmia including torsades de pointes.

Renal

Interstitial nephritis, renal failure.

Nervous System/Psychiatric

Peripheral neuropathy that may be irreversible, Guillain-Barré syndrome, ataxia, paresthesia, hypoesthesia, psychic disturbances including psychotic reactions and confusion.

Musculoskeletal

Tendinitis, tendon rupture; exacerbation of myasthenia gravis; elevated creatine kinase (CK), muscle spasms.

Hematologic

Neutropenia; leukopenia; agranulocytosis; hemolytic anemia, sometimes associated with glucose-6phosphate dehydrogenase deficiency; thrombocytopenia.

Special Senses

Hearing loss, tinnitus, diplopia, dysgeusia.

Other adverse events reported with quinolones include: agranulocytosis, albuminuria, candiduria, crystalluria, cylindruria, dysphagia, elevation of blood glucose, elevation of serum cholesterol, elevation of serum potassium, elevation of serum triglycerides, hematuria, hepatic necrosis, symptomatic hypoglycemia, nystagmus, postural hypotension, prolongation of prothrombin time, and vaginal candidiasis.

What drugs interact with Noroxin (norfloxacin)?

  • Quinolones, including Noroxin, have been shown in vitro to inhibit CYP1A2. Concomitant use with drugs metabolized by CYP1A2 (e.g., caffeine, clozapine, ropinirole, tacrine, theophylline, tizanidine) may result in increased substrate drug concentrations when given in usual doses. Patients taking any of these drugs concomitantly with norfloxacin should be carefully monitored.
  • Elevated plasma levels of theophylline have been reported with concomitant quinolone use. There have been reports of theophylline-related side effects in patients on concomitant therapy with norfloxacin and theophylline. Therefore, monitoring of theophylline plasma levels should be considered and dosage of theophylline adjusted as required.
  • Elevated serum levels of cyclosporine have been reported with concomitant use of cyclosporine with Noroxin. Therefore, cyclosporine serum levels should be monitored and appropriate cyclosporine dosage adjustments made when these drugs are used concomitantly.
  • Quinolones, including Noroxin, may enhance the effects of oral anticoagulants, including warfarin or its derivatives or similar agents. When these products are administered concomitantly, prothrombin time or other suitable coagulation tests should be closely monitored.
  • The concomitant administration of quinolones including Noroxin with glyburide (a sulfonylurea agent) has, on rare occasions, resulted in severe hypoglycemia. Therefore, monitoring of blood glucose is recommended when these agents are co-administered.
  • Diminished urinary excretion of Noroxin has been reported during the concomitant administration of probenecid and Noroxin.
  • The concomitant use of nitrofurantoin is not recommended since nitrofurantoin may antagonize the antibacterial effect of Noroxin in the urinary tract.
  • Multivitamins, or other products containing iron or zinc, antacids or sucralfate, should not be administered concomitantly with, or within 2 hours of, the administration of Noroxin, because they may interfere with absorption resulting in lower serum and urine levels of Noroxin.
  • Videx (Didanosine) chewable/buffered tablets or the pediatric powder for oral solution should not be administered concomitantly with, or within 2 hours of, the administration of Noroxin, because these products may interfere with absorption resulting in lower serum and urine levels of Noroxin.
  • Some quinolones have also been shown to interfere with the metabolism of caffeine. This may lead to reduced clearance of caffeine and a prolongation of the plasma half-life that may lead to accumulation of caffeine in plasma when products containing caffeine are consumed while taking Noroxin.
  • The concomitant administration of a non-steroidal anti-inflammatory drug (NSAID) with a quinolone, including Noroxin, may increase the risk of CNS stimulation and convulsive seizures. Therefore, Noroxin should be used with caution in individuals receiving NSAIDS concomitantly.

Summary

Noroxin (norfloxacin) is a fluoroquinolone antibiotic used to treat a variety of infections such as urinary tract infections (UTIs), gonorrhea, E. coli, and others. Common side effects of Noroxin include nausea, stomach cramps, dizziness, headache, abdominal pain, diarrhea, abnormal heart beats, and photosensitivity (sun sensitivity). There are no adequate and well-controlled studies of Noroxin in pregnant women. It is unknown if Noroxin enters breast milk.

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Medically Reviewed on 8/19/2020
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.