Nitrofurantoin
Also known as: Macrodantin, Macrobid, Furadantin
Nitrofurantoin is an antibiotic specifically used to treat bladder infections. It concentrates in the urine to kill bacteria but does not work for infections in other parts of the body. * **Give with Food**: Always give this medication with a meal or a treat. This significantly reduces stomach upset (vomiting) and helps the body absorb the drug better. * **Timing is Key**: If your pet is on a once-daily preventative dose, give it **right at bedtime**, immediately *after* their last bathroom break for the night. This allows the medication to sit in the bladder overnight and fight bacteria. * **Watch for Side Effects**: The most common side effect is vomiting. If vomiting is severe or persists, contact your veterinarian. * **Liver Warning**: Rarely, this drug can affect the liver. Contact your vet immediately if you notice yellowing of the eyes or gums, severe lethargy, or loss of appetite. * **Finish the Prescription**: Even if your pet seems to feel better, finish the entire course of antibiotics to prevent the infection from returning or becoming resistant.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Susceptible bacterial urinary tract infections
- Recurrent UTI (Conventional dose)
- Recurrent UTI (Prophylactic dose)
- Susceptible bacterial urinary tract infections
- Urinary tract infections (lower UTI only)
- Susceptible urinary tract infections
- Susceptible urinary tract infections
- Prevention of re-infections with gram-negative organisms
- Recurrent UTI (Conventional dose)
- Recurrent UTI (Prophylactic dose)
- Susceptible bacterial urinary tract infections
- Susceptible bacterial urinary tract infections
- Susceptible bacterial urinary tract infections
How it is given
Possible side effects
- Gastrointestinal disturbances (vomiting, nausea, diarrhea)
- Hepatopathy (can be severe or chronic)
- Myasthenic-like effects (rare, reversible in dogs)
- Infertility in male dogs
- Peripheral neuropathy (rare)
- Hemolytic anemia (rare)
- Pneumonitis (rare)
- Emesis
- Diarrhoea
- Gastrointestinal bleeding
- Hepatotoxicity
- Peripheral neuritis (rare)
- Pulmonary complications (rare)
- Thrombocytopenia (at high doses)
Cautions & contraindications
- Renal impairment (decreased efficacy and increased risk of systemic toxicity)
- Known hypersensitivity to nitrofurantoin
- Pregnant patients at term (risk of hemolytic anemia in neonates)
- Neonates
- Rats (high risk of neurotoxicity)
- Significant renal impairment (decreased excretion leads to toxic serum levels)
- Pregnancy (mutagenic properties)
- Pyelonephritis
- Systemic infections outside the urinary tract
- Food-producing animals
- > **Renal Function Warning**: Do not use in patients with compromised renal function. The drug relies on renal excretion to reach the site of infection (the bladder); poor kidney function means the drug won't work for the UTI and will accumulate in the blood, causing toxicity. * **Hepatotoxicity**: Can cause drug-induced hepatopathy. Monitor liver enzymes if adverse effects are suspected, especially during long-term prophylactic use. * **Reproductive Warning**: May cause infertility in male dogs. Use with caution in breeding animals. * **Lab Interference**: May cause false-positive urine glucose results if using cupric-sulfate solutions (e.g., Clinitest). May also cause decreases in blood glucose and increases in serum creatinine, bilirubin, and ALP.
Drug interactions
- Fluoroquinolones (e.g., enrofloxacin, ciprofloxacin): Nitrofurantoin may antagonize the antimicrobial activity of fluoroquinolones; concomitant use should be avoided.
- Food or Anticholinergic drugs: May increase the oral bioavailability and absorption of nitrofurantoin.
- Magnesium trisilicate containing antacids: May inhibit the oral absorption of nitrofurantoin.
- Probenecid: May inhibit the renal excretion of nitrofurantoin, potentially increasing systemic toxicity and reducing its effectiveness in the urinary tract.
- Antimuscarinic drugs: Delays gastric emptying time and increases absorption/bioavailability of nitrofurantoin
- Food: Delays gastric emptying time and increases absorption/bioavailability of nitrofurantoin
- Fluoroquinolones: Antagonism of antibacterial efficacy
- Spironolactone: May increase the hyperkalaemic effects of spironolactone
- Urine alkalinizing agents: Significantly decreases the antibacterial activity of nitrofurantoin
Frequently asked questions
What is Nitrofurantoin used for in pets?
Nitrofurantoin is an antibiotic specifically used to treat bladder infections. It concentrates in the urine to kill bacteria but does not work for infections in other parts of the body. * **Give with Food**: Always give this medication with a meal or a treat. This significantly reduces stomach upset (vomiting) and helps the body absorb the drug better. * **Timing is Key**: If your pet is on a once-daily preventative dose, give it **right at bedtime**, immediately *after* their last bathroom break for the night. This allows the medication to sit in the bladder overnight and fight bacteria. * **Watch for Side Effects**: The most common side effect is vomiting. If vomiting is severe or persists, contact your veterinarian. * **Liver Warning**: Rarely, this drug can affect the liver. Contact your vet immediately if you notice yellowing of the eyes or gums, severe lethargy, or loss of appetite. * **Finish the Prescription**: Even if your pet seems to feel better, finish the entire course of antibiotics to prevent the infection from returning or becoming resistant.
Is Nitrofurantoin safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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