Nitrofurantoin: application, side effects, dosage, precautions.


Nitrofurantoin is an oral antibiotic used to treat certain urinary tract infections (UTIs) . The drug stops the growth of bacteria and is used to treat active UTIs or to prevent infections in people with recurrent UTIs .

Nitrofurantoin cannot treat viral or fungal infections. It should only be used if it is proven, or there are serious reasons to believe, that bacteria are causing UTIs. The misuse of nitrofurantoin can increase the risk of toxicity and resistance to antibiotics .

Nitrofurantoin, marketed under a variety of brand names and formulations (including Macrodantin, Macrobid, Furadantin, and others), is on the World Health Organization's Essential Drug List and is the most prescribed drug for pregnant women in the United States, according to a 2015 report . Obstetrics and gynecology study.

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Nitrofurantoin has been used since the 1950s and is FDA approved for the treatment and prevention of bacterial UTIs, including acute cystitis .

Emerging global resistance to other antibiotics, including fluoroquinolones and bactrim (trimethoprim / sulfamethoxazole), has generated increased demand for underutilized antibiotics such as nitrofurantoin.

Unlike other commonly prescribed antibiotics, nitrofurantoin has a low potential for drug resistance. This, combined with its high degree of effectiveness, makes it an ideal first-line option for treating UTIs without complications.

According to FDA prescription recommendations, nitrofurantoin exhibits good activity against the following bacteria:

On the other hand, nitrofurantoin is not active against most strains of Proteus or Serratia bacteria or any species of Pseudomonas . Additionally, some strains of Enterobacter and Klebsiella are resistant to nitrofurantoin.

Although nitrofurantoin is effective in treating bladder infections , it is less able to penetrate kidney tissue and should never be used to treat pyelonephritis (kidney infection) or perirenal abscesses (kidney abscesses caused by a blockage of the urinary tract).

Before drinking

The biggest concern with any antibiotic is the risk of drug resistance. Because antibiotics are often overused or used incorrectly, pathogenic (disease-causing) bacteria can quickly develop resistance to some of the most commonly prescribed medications.

To make matters worse, some of these bacteria can spread through communities, which means you can contract bacteria that are already resistant to one or more antibiotics.

To avoid resistance, your healthcare provider must first make sure your UTI is caused by bacteria and not a virus or fungus. This can be done by taking a urine sample and performing a culture and antibiotic susceptibility test (AST).

In the absence of evidence, nitrofurantoin may be prescribed if you have recurrent urinary tract infections (antibiotic prophylaxis) based on previous urine cultures.

Feel free to request a urine culture and antibiotic susceptibility test if you have recurring UTIs despite treatment.

It can take one to three days to get results and costs between $ 40 and $ 100 on average. Most health insurance plans cover part or all of the cost.

Precautions and contraindications.

Nitrofurantoin can be used in adults and children, but should be avoided in babies under one month of age due to the risk of hemolytic anemia . Hemolytic anemia is a condition in which red blood cells are destroyed faster than they can be produced.

The same risks limit its use during pregnancy. In fact, nitrofurantoin is contraindicated for pregnant women at term (38 to 42 weeks), during labor and delivery, and when labor is imminent.

Since the drug is excreted primarily through the kidneys, nitrofurantoin should be avoided in people with severe renal impairment (as measured by creatinine clearance less than 60 milliliters per minute or by elevated serum creatinine levels ).

Other antibiotic options

Depending on the results of your urinalysis, nitrofurantoin may or may not be recommended. If nitrofurantoin is not suitable, other first-line medications include Bactrim or a broad-spectrum antibiotic known as fosfomycin. Augmentin (amoxicillin / clavulanic acid) and cephalosporin antibiotics such as rocefin (ceftriaxone) or suprax (cefixime) can also be used.

The FDA advises against the use of fluoroquinolones when other options are available due to their high strength and increased risk of serious side effects.


Nitrofurantoin is available in capsule form for adults and older children. There are several different formulations, each with different indications and / or uses:

  • Macrodantin and furadantin are preparations made from nitrofurantoin macrocrystals and are offered in 25 milligram (mg), 50 mg, and 100 mg capsules.
  • Macrobid is made from nitrofurantoin monohydrate and is only available in 100 mg capsules.
  • Furadantin oral suspension is for children in the form of 25 milligrams per 5 milliliters (25 mg / 5 ml).

The manufacturer's recommended dose depends on age and body weight, as well as whether the drug is used therapeutically (as treatment) or prophylactically (as prophylaxis).

All indicated doses are indicated by the manufacturer of the drug. Check your prescription and talk to your doctor to make sure you are taking the correct dose.

For adults and children over 12 years:

  • Macrodantin or furadantin? 50 to 100 mg every six hours for seven consecutive days.
  • Macrobid? 100 mg every 12 hours for seven days.
  • Prevention of urinary tract infection : macrodantin or furadantin 50 to 100 mg daily for up to 12 months.

For children from 1 month to 12 years:

  • Furadantin suspension? 5 to 7 mg per kilogram (mg / kg) per day, given in four divided doses over seven days.
  • Preventing UTIs? 1 to 2 mg / kg daily as a single or divided dose.

If treatment is ineffective, increasing the dose or duration of therapy is rarely beneficial and can only increase the risk of toxicity and drug resistance.

How to take and store

Nitrofurantoin should be taken with meals to improve the absorption of the drug. The oral suspension can also be mixed with fruit juice, milk, or a mix to improve the taste.

To reduce your risk of drug resistance, it is important to take your antibiotics as prescribed and to the end, even if you feel better. Interrupting or skipping doses early allows resistant bacteria to escape and multiply, reducing the effectiveness of the antibiotic the next time.

Nitrofurantoin is most effective when doses are spread evenly throughout the day. If you need to take a dose every six hours, set an alarm to remind you. If a six-hour dose is too difficult, ask your doctor to prescribe a 12-hour dose of Macrobid.

Nitrofurantoin capsules and oral suspension can be stored at room temperature, ideally 68 to 77 F (20 to 25 C). Store the medicine in a dry cabinet away from heat and direct sunlight.

Side effects

Like all medicines, nitrofurantoin can cause side effects. Most are low grade and rarely cause treatment discontinuation. Other side effects are potentially serious, but occur more often with long-term or continuous treatment.


The most common side effects of nitrofurantoin are:

  • Headache
  • Nausea
  • Threw up
  • Loss of appetite
  • Diarrhea

Some of these symptoms will go away as your body adjusts to the treatment. Others may persist and require over-the-counter medications to relieve nausea, headaches, or diarrhea. Taking nitrofurantoin with food can also help.

Nitrofurantoin can sometimes cause a darkening of the urine. It is harmless and does not indicate liver problems. After cessation of treatment, the color normalizes.

Serious side effects

In rare cases, a condition called a pulmonary hypersensitivity reaction, or PHR, can occur. This occurs most often when nitrofurantoin has been used for more than six months, although it can sometimes occur after two weeks.

In some cases, the reaction can be fatal if the symptoms are not recognized and treated in time. Symptoms include:

  • Fatigue
  • Discomfort
  • Difficulty breathing when exercising
  • Cough
  • Involuntary weight loss
  • Hot
  • Shaking chills
  • Chest pain

In severe cases, PHR can cause severe pneumonitis (inflammation of the lungs) and pulmonary fibrosis (scarring of the lungs).

Call your doctor if you experience chronic fatigue or cannot catch your breath after normal activity while taking nitrofurantoin. This is especially important if you also experience a fever, chills, a persistent cough, or chest pain.

Warnings and interactions

Nitrofurantoin should be used with caution in people with liver or kidney disease. Even if your liver and kidney enzymes are on the verge of normal, long-term use of nitrofurantoin can cause significant and even serious deterioration.

Kidney function should be measured before starting treatment and regularly monitored if nitrofurantoin is used prophylactically. Liver function should also be monitored.

If kidney failure or hepatitis develops while taking nitrofurantoin, treatment should be stopped immediately.


Although few drug interactions have been associated with nitrofurantoin, some may be significant enough to warrant treatment adjustments. Interactions of concern include:

  • Antacids can reduce the rate and degree of absorption of nitrofurantoin from the intestines. Dividing the doses of the two drugs can help, but it is generally best to avoid taking antacids during antibiotic treatment.
  • Gout medications such as probenecid and sulfinpyrazone can reduce the excretion of nitrofurantoin from the kidneys, resulting in toxicity. A reduction in the nitrofurantoin dose may be necessary.
  • Antibiotics such as nitrofurantoin can interfere with hormonal contraceptives , making them less effective and increasing the risk of pregnancy. When taking hormonal contraceptives with nitrofurantoin, additional forms of contraception may be required.

Nitrofurantoin can also interfere with the results of urine glucose tests. Tell your doctor or the laboratory staff if you plan to have this test done while taking nitrofurantoin.

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