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Nalidixic acid (Oral route)


nal-i-DIX-ik AS-id

Brand Names:

  • Neggram

Dosage Forms:

  • Tablet
  • Suspension





Non-Fluorinated Quinolone

Uses of This Medicine:

Nalidixic acid is used to treat infections of the urinary tract. This medicine belongs to the group of medicines known as quinolone antibiotics. It works by killing the bacteria and 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.

Before Using This Medicine:

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 nalidixic acid in infants younger than 3 months of age. Safety and efficacy have not been established.

Older adults

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of nalidixic acid in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require an adjustment in the dose for patients receiving nalidixic acid.


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.


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.

Other medicines

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 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.

  • Ajmaline
  • Disopyramide
  • Pirmenol
  • Prajmaline
  • Procainamide
  • Quinidine

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.

  • Melphalan
  • Warfarin

Other interactions

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. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

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), history of or
  • Diarrhea or
  • Heart attack, recent or
  • Heart rhythm problems (e.g., QT prolongation), history of or
  • Hypokalemia (low potassium in the blood) or
  • Liver disease Use with caution. May make these conditions worse.
  • Cerebral arteriosclerosis (hardening of the arteries in the brain) or
  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency May cause side effects to become worse.
  • Convulsive disorders (seizures, epilepsy), history of or
  • Porphyria (enzyme problem) Should not be used in patients with these conditions.
  • Kidney disease Effects may be increased because of slower removal of the medicine from the body.

Proper Use of This Medicine:

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 may be taken with or without food. Drink plenty of fluids every day while you are using nalidixic acid.

If you or your child are taking aluminum, calcium, or magnesium-containing antacids, didanosine oral liquid (e.g., Videx®), iron supplements, multivitamins, zinc, or sucralfate (e.g., Carafate®), 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 the nalidixic acid.

To help clear up your infection completely, keep taking this medicine for the full time of treatment, even if you or your child begin to feel better after a few days. Do not miss any doses.


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 forms (tablets):
    • For urinary tract infection:
      • Adults, teenagers, and children 12 years of age and older At first, 1000 milligrams (mg) four times a day. Your doctor may adjust your dose if needed.
      • Children 3 months to 12 years of age Dose is based on body weight and must be determined by your doctor. At first, the dose is usually 55 milligrams (mg) per kilogram (kg) of body weight per day, divided and given in four doses. Your doctor may adjust your dose if needed.
      • Infants younger than 3 months of age Use is not recommended.

Missed dose

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.


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.

Precautions While Using This Medicine:

If you will be taking this medicine for more than 2 weeks, it is very important that your doctor check you or your child's progress at regular visits. Blood tests may be needed to check for unwanted effects.

If your or your child's symptoms do not improve within 2 days, or if they become worse, check with your doctor.

Do not breastfeed while you are using this medicine.

Do not use melphalan (e.g., Alkeran®) or other similar cancer medicines while you are taking this medicine. Using these medicines together may increase your risk for more serious side effects.

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 or your child have a rash; itching; hives; hoarseness; shortness of breath; trouble with breathing; trouble with swallowing; or any swelling of your hands, face, or mouth after you take this medicine.

Nalidixic acid may cause diarrhea, and in some cases it can be severe. 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 or your child start having numbness, tingling, or burning pain in your hands, arms, legs, or feet. These may be symptoms of a condition called peripheral neuropathy.

This medicine may rarely cause inflammation or 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 or if you are also using steroid medicines (e.g., dexamethasone, prednisolone, prednisone, Medrol®). If you or your child get sudden pain in a tendon after exercise (e.g., in the ankle, back of the knee or leg, shoulder, elbow, or wrist), stop taking nalidixic acid and check with your doctor right away. Rest and do not exercise until the doctor has made sure that you have not injured or torn the tendon.

This medicine may cause blurred vision or other vision problems. It may also cause some people to become dizzy, 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 or able to see well. If these reactions are especially bothersome, check with your doctor.

This medicine may increase the central nervous system (CNS) stimulant effects of caffeine-containing foods or beverages, such as chocolate, cocoa, tea, coffee, and cola drinks. Avoid eating or drinking large amounts of these foods or beverages while using this medicine. If you have questions about this, check with your doctor.

Nalidixic acid may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin using this medicine:

  • Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
  • Wear protective clothing, including a hat. Also, wear sunglasses.
  • Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients 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.
  • Apply a sun block lipstick that has an SPF of at least 15 to protect your lips.
  • Do not use a sunlamp, tanning bed, or tanning booth.

If you or your child have a severe reaction from the sun, stop using this medicine and check with your doctor right away.

This medicine may cause false test results with some urine glucose (sugar) tests. If you or your child are diabetic, check with your doctor before changing your diet or the dose of your diabetes medicine while you are using nalidixic acid.

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.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common
Skin rash
Less common
Blurred or decreased vision
change in color vision
double vision
halos around lights
overbright appearance of lights
Abdominal or stomach cramps or pain (severe)
blistering, peeling, or loosening of the skin and mucous membranes
bulging of fontanel (soft spot) on top of the head of an infant
burning or tingling skin sensation
changes in facial skin color
convulsions (seizures)
dark or amber urine
diarrhea, watery and severe, which may also be bloody
general feeling of discomfort or illness
hallucinations (seeing, hearing, or feeling things that are not there)
headache (severe)
increased frequency of breathing
joint pain, stiffness, or swelling
mood or other mental changes
nausea or vomiting
pale skin
pale stools
red skin lesions, often with a purple center
shortness of breath
sore throat
sudden trouble in swallowing or breathing
swelling of the face, mouth, hands, or feet
unusual bleeding or bruising
unusual tiredness or weakness
visual changes
yellow eyes or skin
Incidence not known
Black, tarry stools
bone pain
burning, numbness, tingling, or painful sensations
chest pain
difficulty with swallowing
large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
lower back or side pain
painful or difficult urination
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
redness of the skin
sores, ulcers, or white spots on the lips or in the mouth
swollen glands
tightness in the chest
unsteadiness or awkwardness
weakness in the arms, hands, legs, or feet

Get emergency help immediately if any of the following symptoms of overdose occur:

Symptoms of overdose
Aggressive and violent behavior
change in the ability to see colors, especially blue or yellow
loss of appetite
rapid, deep breathing
trouble with sleeping
unable to sleep
unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
feeling of constant movement of self or surroundings
stomach pain
Less common
Increased sensitivity of the skin to sunlight
Incidence not known
Difficulty with moving
muscle pain or stiffness

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 6/12/2013
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