What is Norfloxacin?

Commonly Used Brand Name(s)Noroxin

Therapeutic ClassificationsAntibiotic



Blackbox WarningTOP

Oral route (Tablet)

Fluoroquinolones, including norfloxacin, are associated with disabling and potentially irreversible serious adverse reactions that have occurred together, including tendinitis and tendon rupture, peripheral neuropathy, and CNS effects. Discontinue norfloxacin and avoid use of fluoroquinolones in patients with these serious adverse reactions. Reserve use of norfloxacin for patients with no alternative treatment options for an uncomplicated UTI (including cystitis). Fluoroquinolones, including norfloxacin, may exacerbate muscle weakness in persons with myasthenia gravis. Avoid in patients with known history of myasthenia gravis .


Norfloxacin is used to treat certain bacterial infections in many different parts of the body. Norfloxacin may mask or delay the symptoms of syphilis. It is not effective against syphilis infections.

Norfloxacin belongs to the class of medicines known as quinolone antibiotics. It works by killing bacteria or preventing their growth. However, this medicine will not work for colds, flu, or other virus infections.

This medicine is available only with your doctor's prescription.

Proper UseTOP

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

This medicine comes with a Medication Guide. Read and follow the instructions carefully. Ask your doctor if you have any questions.

Swallow the tablet with a glass (8 ounces) of water. Drink plenty of fluids while you are being treated with this medicine. Drinking extra water will help to prevent some unwanted effects of norfloxacin.

Norfloxacin should be taken at least 1 hour before or 2 hours after a meal, milk, or other dairy products.

If you are taking aluminum or magnesium-containing antacids, iron supplements, multivitamins, Didanosine (Videx®), sucralfate (Carafate®), or zinc, do not take them at the same time that you take this medicine. It is best to take these medicines at least 2 hours before or 2 hours after taking norfloxacin. These medicines may keep norfloxacin from working properly.

Avoid caffeine-containing products (eg, coffee, soda, or chocolate) while you are using this medicine. Norfloxacin may cause caffeine to stay in your body longer than usual.

Keep using this medicine for the full treatment time, even if you feel better after the first few doses. Your infection may not clear up if you stop using the medicine too soon.


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For infections:
      • Adults—400 milligrams (mg) every 12 hours for 3 to 21 days, depending on the medical problem being treated. Prostatitis is usually treated for 28 days. Gonorrhea is usually treated with a single oral dose of 800 mg.
      • Children—Use and dose must be determined by your doctor.

Missed DoseTOP

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Use & StorageTOP

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Before UsingTOP

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of norfloxacin in the pediatric population. Safety and efficacy have not been established.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of norfloxacin in the elderly. However, elderly patients are more likely to have age-related heart or kidney problems, or develop severe tendon problems (including tendon rupture), which may require caution and an adjustment in the dose for patients receiving norfloxacin.


Pregnancy CategoryExplanation
All TrimestersCAnimal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.

Breast FeedingTOP

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug InteractionsTOP

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Other InteractionsTOP

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

  • Dairy Food

Other Medical ProblemsTOP

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Bradycardia (slow heartbeat) or
  • Diabetes or
  • Diarrhea or
  • Heart disease or
  • Heart rhythm problems (eg, prolonged QT interval), or family history of or
  • Hypokalemia (low potassium in the blood), uncorrected or
  • Liver disease (including hepatitis) or
  • Myocardial ischemia (reduced blood supply in the heart) or
  • Seizures (epilepsy), or history of—Use with caution. May make these conditions worse.
  • G6PD deficiency (an enzyme problem)—Anemia may occur while using this medicine.
  • Myasthenia gravis (severe muscle weakness), or history of or
  • Tendinitis (inflammation of the tendon), history of or
  • Tendon rupture, history of—Should not be used in patients with these conditions.


It is very important that your doctor check your progress while you are using this medicine. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. Blood and urine tests may be needed to check for unwanted effects.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

This medicine may cause serious allergic reactions including anaphylaxis, which can be life-threatening and require immediate medical attention. Call your doctor right away if you have a rash, itching, hives, hoarseness, trouble with breathing, trouble with swallowing, or any swelling of your hands, face, or mouth after you receive this medicine.

Serious skin reactions can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, red skin lesions, severe acne or skin rash, sores or ulcers on the skin, or fever or chills while you are using this medicine.

Check with your doctor right away if you have dark urine, clay-colored stools, abdominal or stomach pain, or yellow eyes or skin. These maybe symptoms of a serious liver problem.

Norfloxacin may cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert. If these reactions are especially bothersome, check with your doctor.

Norfloxacin may cause diarrhea, and in some cases it can be severe. It may occur 2 months or more after you stop using this medicine. Do not take any medicine to treat diarrhea without first checking with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If you have any questions about this or if mild diarrhea continues or gets worse, check with your doctor.

Tell your doctor right away if you start having numbness, tingling, or burning pain in your hands, arms, legs, or feet. These may be symptoms of a condition called peripheral neuropathy.

Norfloxacin may rarely cause inflammation or even tearing of a tendon (the cord that attaches muscles to bones). The risk of having tendon problems may be increased if you are over 60 years of age, using steroid medicines (eg, dexamethasone, prednisolone, prednisone, or Medrol®), if you have severe kidney problems, a history of tendon problems (eg, rheumatoid arthritis), or if you have received an organ (eg, heart, kidney, or lung) transplant. If you get sudden pain or swelling in a tendon after exercise (eg, in the ankle, back of the knee or leg, shoulder, elbow, or wrist), check with your doctor right away. Refrain from exercise until your doctor says otherwise.

Tell your doctor right away if you have any of the following symptoms while using this medicine: convulsions, feeling anxious, confused, or depressed, seeing, hearing, or feeling things that are not there, severe headache, trouble sleeping, or unusual thoughts or behaviors.

Some people who take norfloxacin may become more sensitive to sunlight than they are normally. Exposure to sunlight, even for brief periods of time, may cause severe sunburn, or skin rash, redness, itching, or discoloration. When you begin using this medicine:

  • Stay out of direct sunlight, especially between the hours of 10:00 AM and 3:00 PM, if possible.
  • Wear protective clothing, including a hat and sunglasses.
  • Apply a sun block product that has a sun protection factor (SPF) of at least 15. Some people may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your doctor.
  • Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction from the sun, check with your doctor.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Chemical ClassificationsTOP

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