NITROFURANTOIN (Macrobid): What is used for?

What is Nitrofurantoin?

Nitrofurantoin (Nitrofurantoina) is a drug used to treat urinary tract infections. The product ingredients are: Nitrofurantoin monohydrate, Nitrofurantoin sodium.

The brand names of Nitrofurantoin are: Macrobid, Macrodantin, Furadantin.

Mechanism of action (MOA) of Nitrofurantoin

Bactericide. It interferes with the enzymatic processes of cellular respiration, glucidic metabolism and bacterial wall synthesis.

Therapeutic Indications, Uses and Benefits of Nitrofurantoin

Acute cystitis in girls, adolescents and adult women.

Nitrofurantoin Dosage

Adults: 50-100 mg/8 h.
girls > 6 years and adolescents 12-<18 years: 5-7 mg/kg/day in 4 doses (max. dose = adult dose); girls > 3 months: 1-2 mg/kg/6 h (max. dose = adult dose).
Duration of treatment: 5-7 days.

Mode of administration 

It is recommended to take it orally during meals or with a glass of milk.

Contraindications of Nitrofurantoin

Hypersensitivity to nitrofurantoin and other nitrofurans; prolonged, continuous (> 7 days) or intermittent treatments; Renal failure with Clcr < 45 ml/min; Acute porphyria; G6PDH deficiencies; Last 2 weeks of pregnancy due to risk of fetal hemolytic anemia; Children < 3 months.

Warnings and Precautions with Nitrofurantoin

Not indicated in prophylactic treatment of recurrent urinary tract infections, treatment of male urinary tract infections, upper urinary tract infections, bacteremia or sepsis secondary to it.

Assess risk/benefit in case of history or suspicion of infection by multidrug-resistant microorganisms; caution in: reanl insufficiency with Clcr 30-44 ml/min, lung disease, impairment of liver function, predisposition to allergic reactions, anemia, diabetes mellitus, electrolyte imbalance, weakness or deficit of vit. B (particularly of folic acid).

Interrupt treatment if hepatic alterations appear, in pulmonary function, symptoms of hypersensitivity or neurological (paresthesias); false + in tests with glucose tests in urine.

Patients should undergo periodic examinations to identify changes in biochemical tests that are indicative of liver damage.

Liver failure


Kidney failure

Contraindicated in renal insufficiency with Clcr < 45 ml/min. Caution in renal insufficiency with Clcr 30-44 ml/min.

Interactions with Nitrofurantoin

  • Increased absorption with: food, agents that delay gastric emptying.
  • Decreased absorption with: some antacids (magnesium trisilicate), spacing 2 h.
  • Decreased renal excretion with: probenecid and sulfinpirazone.
  • Antagonistic effect with: quinolones.
  • Decreased action with: acetazolamide, dichlorphenamide, potassium citrate and sodium bicarbonate.


Contraindicated in the last two weeks of pregnancy due to the risk of fetal hemolytic anemia.


Nitrofurantoin is detected in small traces in breast milk, so the use of this antibiotic should be avoided by the mother in the case of infants under three months of age due to the risk of hemolysis due to the immaturity of the erythrocyte enzyme system, as well as in those infants over three months of age with suspected or diagnosed erythrocyte enzyme deficiencies such as glucose-6-phosphate dehydrogenase deficiency.

Effects on driving ability

May cause dizziness, so its use should be avoided.

Adverse reactions and side effects of Nitrofurantoin

Allergic skin reactions (itching, hives), pseudo-lupus manifestations (fever, chills, arthralgia) sometimes associated with pulmonary symptoms, angioedema; dizziness, peripheral neuropathies associated with overdose or decreased renal elimination (renal failure) or a contributing factor (diabetes, alcoholism, advanced age, prolonged treatments); nausea, vomiting, abdominal pain, diarrhea.

After evaluation of the pharmacovigilance data, the following have been observed: interstitial nephritis, hepatitis, autoimmune hepatitis, cholestatic jaundice, chronic active hepatitis, hepatic necrosis and cutaneous vasculitis.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


UNII: 927AH8112L
NCI Thesaurus: C29293

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