Nitrofurantoin

What is nitrofurantoin?

Nitrofurantoin is an antibiotic used to treat bacterial urinary bladder infections. It is typically used as a second-line antibiotic, when broad-spectrum antibiotics have not cleared the infection.

It is used “off label” or “extra label” in veterinary medicine. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions carefully.

How do I give my pet nitrofurantoin?

Nitrofurantoin comes in capsule or liquid suspension forms.

• Liquids and capsules are given orally (by mouth).
• This medication should be given with food. 
• Liquid medications must be measured carefully. Contact your veterinarian if you have trouble measuring or giving the medication.
• Give this medication to your pet for the entire time prescribed by your veterinarian, even if it appears that your pet is feeling better.

This medication may start working within 1–2 hours. This medication is short-acting, meaning that effects should stop within 24 hours.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once. 

Are there any potential side effects from nitrofurantoin?

Nitrofurantoin may cause the following side effects:

• vomiting, stomach upset

The following reactions are rare, but if they occur, contact your veterinarian immediately:

• an allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face
• signs of liver toxicity (jaundice, severe vomiting, seizures, changes in behavior, changes in urine color)
• signs of nerve toxicity or low blood sugar (weakness, confusion, tremors)

Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses, but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.

Are there any risk factors for this medication?

This medication should NOT BE USED in:

• rats
• animals with known allergies to any component of the medication
• animals with known kidney disease
• food-producing animals or animals intended for food

This medication should be USED WITH CAUTION in animals who: 

• are diabetic
• have liver disease
• are used for breeding
• are pregnant or nursing

Are there any drug interactions I should be aware of?

Certain medications should be USED WITH CAUTION when given with nitrofurantoin, including: 

• anticholinergic drugs (e.g., atropine)
• fluconazole
• fluoroquinolone antibiotics (e.g., enrofloxacin)
• local anesthetics (e.g., lidocaine)
• probenecid
• psyllium
• spironolactone

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

Your veterinarian may schedule a follow-up visit to ensure the infection has been cleared and/or do additional testing to ensure this is the right medication for the type of infection present. In this case, follow your veterinarian’s directions.

How do I store nitrofurantoin?

• Store at room temperature in original container. 
• Protect from light, freezing, and contact with metals.
• Keep medication out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.