What is rifampin?
Rifampin (brand name: Rifadin®) is an antimicrobial medication that is primarily used to treat bacterial infections, although it can also help treat fungal and viral infections. It is most used to treat a certain infection in horses, but it has also been used occasionally to treat specific types of infections in dogs and cats.
Its use in cats and dogs to treat infections is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully, as their directions may be significantly different from those on the label.
How is rifampin given?
- Give rifampin by mouth in the form of a capsule or a compounded liquid suspension.
- Give on an empty stomach.
- If vomiting occurs, try giving the medication with food.
- Shake compounded liquid forms of this medicine well before each use and measure each dose carefully.
Because this medication will stain anything it touches to an orange or red color, consider wearing gloves when administering the medication.
This medication takes effect quickly, in about 1 to 2 hours, but its effects may not be noticeable for a few days.
What if I miss giving my pet the medication?
If you miss a dose, give it when you remember. However, if it is close to the time for the next dose, skip the dose you missed, give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.
Are there any potential side effects?
Common side effects in dogs include:
- vomiting
- reduced appetite
- lethargy
- change in the color of urine, tears, and saliva to a red/orange color (can stain fabrics)
Possible side effects in dogs include:
- elevated liver enzymes on bloodwork
- liver toxicity (more common in dogs than other animals)
- yellowing of the eyes, skin, or gums
- vomiting (that continues)
- severe or bloody diarrhea
- painful abdomen (stomach),
- changes in behavior
In cats, liver dysfunction (abnormal or impaired function of the liver) can occur and can cause the following signs:
- reduced appetite
- vomiting
- yellowing of the skin or eyes
This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this medication?
Do NOT use rifampin in pets that are allergic to it.
Use with caution in pets that:
- have known liver dysfunction
- are pregnant or nursing
- are geriatric (liver dysfunction may be more common)
Are there any drug interactions I should be aware of?
Certain medications should be used with caution when given with rifampin, including but not limited to:
- acetaminophen
- fluoroquinolones
- phenobarbital
- benzodiazepines
- atenolol
- chloramphenicol
- corticosteroids
- cyclosporine
- enalapril
- diltiazem
- fluoroquinolones
- mycophenolate
- opioids
- praziquantel
- theophylline
Rifampin can cause serious drug reactions, so be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.
Is there any monitoring that needs to be done with this medication?
- Monitor your pet for side effects associated with liver toxicity.
- Your veterinarian may measure your pet’s liver function prior to starting the medication and again 10-14 days after the medication is started.
- If your veterinarian has prescribed long-term use of rifampin, liver function tests may be done monthly until treatment is complete.
- Your veterinarian may also monitor your pet to be sure that the medication is working.
How do I store rifampin?
- Store rifampin at room temperature between 15°C and 30°C (59°F to 86°F).
- Store rifampin away from light in a tight container.
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.
