The Safety of Azithromycin in Cats

It's important to determine the correct dosage of azithromycin for Kitty.

It's important to determine the correct dosage of azithromycin for Kitty.

If your kitty was ever diagnosed with an infection, it's quite likely your vet prescribed the antibiotic azithromycin for him, marketed under the brand name Zithromax. It gets rid of numerous types of bacteria, but like any medication, it can have side effects.


Developed for human use, azithromycin isn't approved by the U.S. Food and Drug Administration for use in pets, but your vet is permitted to prescribe the medication "off-label." That means she can use it to treat diseases not literally included on the drug's label. Similar to another common antibiotic, erythromycin, it absorbs better and its effects last longer in canines and felines, according to It's available in either tablet or liquid forms. Azithromycin is a powerful antibiotic, so the odds are good that it will get rid of the disease. It's sometimes used when other antibiotics have failed. However, with that power comes certain safety risks that you might not find in less effective antibiotics.


Azithromycin might be used to treat troubles in Kitty from head to toe, inside and out. It's used to treat infections of the skin, ears, gums, urinary tract and respiratory system. If Kitty is diagnosed with Lyme disease or the herpes virus, your vet might prescribe azithromycin. The bacteria chlamydia can cause infections in a cat's eyes or lungs -- azithromycin should cure it. Azithromycin is used to treat bacterial infections caused by Staphylococcus aureus as well as some types of streptococci, mycoplasma, hemophilus, bacteroides and Borrelia burgdorferi.

Side Effects

Side effects of azithromycin in cats tend toward the gastrointestinal. Kitty might experience diarrhea, vomiting or pain in the abdomen. Less often, cardiac irregularities, such as rapid heartbeat, might occur. It can also impair liver function in cats. A sign of liver issues is jaundice, a yellowing of Kitty's mucous membranes, including the whites of his eyes and his gums. Call your vet at once if you see any yellowing. In a worst-case scenario, liver or kidney failure could result.


Your cat shouldn't take azithromycin if he's been diagnosed with kidney or liver disease. Tell your vet about any other medications or supplements Kitty receives, as the combination could lessen the azithromycin's efficacy or cause harm. Antiacids reduce the drug's absorption rate. Needless to say, never give Kitty any azithromycin prescribed for you or a family member.

About the Author

Jane Meggitt has been a writer for more than 20 years. In addition to reporting for a major newspaper chain, she has been published in "Horse News," "Suburban Classic," "Hoof Beats," "Equine Journal" and other publications. She has a Bachelor of Arts in English from New York University and an Associate of Arts from the American Academy of Dramatics Arts, New York City.

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