Norfloxacin - Use | Dose | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Norfloxacin is a drug from the group of fluoroquinolone antibiotics. It works by inhibiting the bacterial enzymes DNA gyrase and topoisomerase IV, which inhibits the synthesis of bacterial DNA, leading to the death of the bacterial cell. It is effective against a wide range of gram positive and gram negative bacteria. It also exerts a bactericidal effect on the bacteria called Escherichia coli - the most common cause of urinary tract infections. For this reason, this medicine is most commonly used to treat urinary tract infections.


This medicine should not be used in the following situations:

  • Hypersensitivity to the quinolone antibiotics
  • Children under the age of 18
  • Pregnancy
  • Arrhythmias

Norfloxacin should not be used in patients who have epilepsy, because studies have shown that fluoroquinolones in rare cases may cause convulsions.1

Norfloxacin may cause tendinopathy and tendon rupture, which most commonly affect the Achilles tendon.2 If you notice pain or any changes in the muscle / tendon, immediately stop taking this drug and contact your doctor.

The studies showed that patients who are exposed to the sun while using this drug have an increased risk of photosensitivity (increased sensitivity to the sunlight). If you notice changes in the skin, you should discontinue therapy immediately.

There have been reported cases of myasthenia gravis egzacerbation in patients taking this medicine.3 For this reason, this medicine must not be used in patients suffering from this disease.

It should not be used in patients who have a deficiency of the enzyme glucose-6-phosphate dehydrogenase, because such patients are at increased risk of hemolytic anemia.

Norfloxacin has been associated with prolongation of the QT interval and should not be used in patients who already have arrhythmias.

Norfloxacin, pregnancy and breastfeeding

Studies on rats have shown that this medicine causes fetal defects and abnormalities4, and its use during pregnancy is not recommended.

For now there is no information on whether this medicine is excreted into breast milk or not, so it is necessary to avoid breastfeeding while you are being treated with this drug.


Norfloxacin exists in the form of a tablet at a dose of 400 mg. Swallow the tablet whole, with 250 ml of water. Do not use mineral water or fruit juices fortified with calcium and magnesium, as this may reduce Norfloxacin absorption and thus reduce its effectiveness. If you're taking preparations of calcium, magnesium and iron, it is necessary to leave a gap of at least two hours between taking these dietary supplements and Norfloxacin tablets.

The recommended dosage is given in the table below:

Indication Recommended dose
Uncomplicated urinary tract infections 400 mg every twelve hours for three consecutive days
Complicated urinary tract infections 400 mg every twelve hours for seven consecutive days
Prevention of recurrent urinary tract infections 400 mg every twelve hours for three months


Norfloxacin may interact with the following medications:

  • Corticosteroids (methylprednisolone, triamcinolone, prednisolone, prednisone, dexamethasone, hydrocortisone and others). Co-administration with these drugs leads to an increased risk of tendinopathy.
  • Narcotic analgesics (tramadol, fentanyl, alfentanil, morphine, and others). Concomitant use with these drugs increases the risk of seizures.
  • Bupropion (a drug used to treat depression and for smoking cessation). Concomitant use with this drug increases the risk of seizures.
  • Antiarrhythmic drugs (disopyramide, amiodarone, sotalol, quinidine, mexiletine, flecainide and propafenone). Concomitant use with these drugs increases the risk of arrhythmia.
  • Clozapine (a drug used in the treatment of psychosis, and schizophrenia).
  • Ropinirole (a drug used to treat Parkinson's disease).
  • Anagrelide (a drug that is indicated for the reduction of the platelets number in the blood). Concomitant use increases the risk of bleeding.
  • Haloperidol and droperidol (antipsychotics). Concomitant use with these drugs increases the risk of arrhythmia.
  • Selective serotonin reuptake inhibitors (antidepressants), such as: escitalopram, citalopram, fluoxetine, sertraline and others. Concomitant use with these drugs increases the risk of arrhythmia.
  • Mifepristone (a drug used for termination of pregnancy). Concomitant use with this drug increases the risk of arrhythmia.

Side effects

Norfloxacin may cause the following side effects:

  • Tendinopathy
  • Prolongation of the QT interval and consequent arrhythmias that can be life-threatening
  • Photosensitivity
  • Stevens-Johnson syndrome
  • Seizures
  • Guillain-Barre syndrome
  • Headache and dizziness
  • Vaginal yeast infection
  • Loss of appetite
  • Depression
  • Anxiety
  • Hallucinations
  • Irritability
  • Loss of kidney function
  • Allergic reactions


  1. NCBI link 1
  2. NCBI link 2
  3. NCBI link 3
  4. NCBI link 4

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