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Do Antibiotics Make Cats Sleepy? Side Effects of Antibiotics

Written by: Christian Adams

Last Updated on June 16, 2024 by Catster Editorial Team

Veterinarian giving injection to cat

Do Antibiotics Make Cats Sleepy? Side Effects of Antibiotics

Antibiotics are one of the most effective ways to fight infections and have been used for several years by veterinarians. While they can help your cat recover from many different ailments, they’re not without their downsides including potential drowsiness.

divider-catclaw1 What Are Antibiotics?

Understanding antibiotics’ effects on the body means understanding what they do. Antibiotics are designed to stop infections caused by bacteria by killing the germs. They’ll only be prescribed for infections caused by bacteria and won’t affect viral or fungal infections.

They were first discovered in 1928 by a Scottish microbiologist. Sir Alexander Fleming discovered penicillin after accidentally leaving a petri dish containing Staphylococcus bacteria open.

<strong>Feline health problems that antibiotics can be used to treat include:</strong>
  • Respiratory infections
  • Urinary tract infections
  • Skin infections
  • Wounds
  • Gastrointestinal upsets
cat examined by Vets
Image Credit: Kzenon, Shutterstock

Do Antibiotics Make Cats Sleepy?

If you’ve noticed your cat sleeping more during their course of antibiotics, there are three reasons for this. Fighting infections, with or without the help of antibiotics, is tiring work. We might not be consciously aware of the fight the body is partaking in, but the signs of battle show themselves in other ways. These signs are often fever or fatigue.

Lethargy can also be caused by the antibiotics. Cats, like people, have varying responses to different drugs. While antibiotics don’t cause fatigue across the board, a few felines can suffer from sleepiness due to the treatment, but it’s one of the rarer side effects. Amoxicillin, in particular, has been known to cause sleepiness in some cats.

There’s also the fact that cats tend to sleep more whenever they’re unwell. They don’t like showing weakness and will prefer to curl up somewhere out of the way to recover quietly.

What Are the Side Effects of Antibiotics?

Not all cats react to antibiotics in the same way. Depending on your cat and the type of antibiotic that they’re on, the side effects could include any of the following.

Allergic Reaction

As with most things your cat comes into contact with, antibiotics can trigger allergic reactions. If you start a new course of antibiotics, watch your cat to ensure they don’t react negatively to their treatment. You should inform your veterinarian if they do.

Allergic reactions to antibiotics can result in skin irritation, like rashes or hives. There is a possibility of severe allergic reactions, such as difficulty breathing.

yellow sad sick cat
Image Credit: Nikolay Bassov, Shutterstock

Antibiotic Resistance

One of the biggest reasons antibiotics are only prescribed for severe bacterial infections is to reduce the chances of your cat developing resistance to the medication. The more often antibiotics are used, the more the bacteria evolve to resist it. This can mean that when your cat really needs the drug, it will be far less effective.


Interactions With Other Drugs

Before you start a course of antibiotics, it’s essential to consider any other medication your cat takes for other health conditions. Your veterinarian should be aware of any possible conflicts between drugs.

If you’ve moved recently or changed your clinic, you should inform your new veterinarian of your cat’s existing medications. Amoxicillin, in particular, can react with:

  • Neomycin sulfate
  • Antacids
  • Aminoglycosides
  • Bacteriostatics
Veterinarian at vet clinic giving injection to cat
Image Credit: Tom Wang, Shutterstock

Secondary Infections

Antibiotics kill bacteria, and while they defeat infections, good bacteria are also killed. The good bacteria keep our cats healthy. That is why it’s recommended to feed probiotic supplements to your cat after they’ve finished a course of antibiotics to help restore their natural bacteria.

Secondary infections, like yeast infections, can be a frequent side effect of antibiotic treatments.


Stomach Upset

The most common reaction to antibiotics is gastrointestinal issues. Diarrhea and vomiting are the most significant issues. Stomach irritation can also lead to loss of appetite, which can cause more problems if your cat refuses to eat.

Sick cat in animal hospital
Image Credit: Kachalkina Veronika, Shutterstock

cat face divider 2

What Are Alternatives to Antibiotics?

The downsides of antibiotics have led to many cat owners seeking alternative methods of treating infections. These methods might take a little longer to implement than simply offering your cat a pill with their dinner, but they can be helpful, especially when your cat is allergic to the prescribed antibiotics.

Antibiotic alternatives include:

  • Good hygiene practices
  • Probiotics
  • Treating the cause of secondary infections (allergies that cause skin infections, for example)
  • Medicated shampoo
  • Topical creams

cat paw divider

Final Thoughts

Antibiotics might be a good way to boost your cat’s immune system when they’re fighting infection, but they have their downsides. Common side effects include allergic reactions, diarrhea, and vomiting. While sleepiness is a side effect, it’s rarer than most other reactions and depends on how your cat reacts to the medication.


Featured Image Credit: Africa Studio, Shutterstock

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