Is It Safe to Give Cats Human Antibiotics?

Serenah McKay
Kitten is sick

Antibiotics are prescribed to treat bacterial infections in both cats and humans, and when your pet is sick, it's natural to wonder if you can use leftover human antibiotics for cats. In some cases, you can, but some medications may put your kitty in danger. Before you give your cat your leftover medication, you must consult a veterinarian for the proper dosage.

Three Safe Human Antibiotics for Cats

A cat's metabolism is extremely sensitive to antibiotics, even those formulated for veterinary use. According to, only three human antibiotics can be safely administered to cats:

  • Amoxicillin - a penicillin-type drug and the most frequently prescribed antibiotic for cats
  • Ampicillin - an older penicillin-type antibiotic
  • Tetracycline - a broad-spectrum antibiotic

In cats, amoxicillin and ampicillin are most often prescribed for infections of the respiratory system, urinary tract, eyes and ears. They may also be given to prevent infection from developing in a bite wound, or to treat an already infected wound. Tetracycline is typically prescribed to treat a tick-borne disease called ehrlichiosis.

Your vet will need to weigh and examine your cat to prescribe the proper dosage. Factors that determine dosage include your cat's weight, symptoms, overall medical condition and any other medications he might be taking.

Possible Side Effects

All medications can potentially cause unpleasant side effects.

Amoxicillin and Ampicillin

Common side effects of amoxicillin and ampicillin include:

  • Upset stomach
  • Vomiting
  • Diarrhea
  • Drooling


Tetracycline can cause nausea and diarrhea, as well as:

  • Difficulty swallowing
  • Tooth discoloration
  • Sensitivity to the sun
  • Delayed bone growth and healing
  • Damage to the liver or kidneys

Signs of an Allergic Reaction

Call your vet right away if your cat shows signs of an allergic reaction:

  • Severe skin rash
  • Itching
  • Hives
  • Swelling of the face, tongue or throat
  • Difficulty breathing or swallowing
  • Dizziness

What to Avoid

There are several antibiotic treatments you should avoid.

Topical Antibiotics

According to the Pet Poison Helpline, the human antibiotics that pose the greatest danger for cats are topical antibiotic ointments such as Neosporin or Bacitracin. A cat licking the ointment off of a wound can ingest enough to cause serious illness or even death.


Also, a class of antibiotics called fluoroquinolones may cause seizures in cats, according to the ASPCA's Animal Poison Control Center. These synthetic broad-spectrum antibacterial drugs are marketed under brand names like Baytril, Cipro and Levaquin. In addition, The Merck Veterinary Manual notes adverse effects of this class of drugs, especially Baytril, on cats include acute retinal degeneration, which can lead to blindness.

Common Signs of Poisoning From Antibiotics

Even veterinary antibiotics can be toxic to cats if improperly administered. Common signs of poisoning from drugs, a drug overdose or any other toxic substance, include:

Call your vet immediately if you notice any of these symptoms after giving antibiotics to your cat.

What Else You Should Know

Follow your vet's instructions for giving your cat his medication. Even if your kitty seems back to his old self, continue the full course of treatment. That will reduce chances of the infection recurring and help your cat stay in perfect health.

Is It Safe to Give Cats Human Antibiotics?