Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Do Antibiotics Make Cats Sleepy? Vet-Reviewed Side Effects of Antibiotics

Veterinarian giving injection to cat

Antibiotics are one of the most effective ways to fight infections and have been used for more than 50 years by veterinarians. While they can help your cat recover from many different ailments, they’re not without their downsides including potential sleepiness.

However, if your cat is lethargic during or after the antibiotic treatment has finished, or they are not eating, get them checked by a veterinarian as there could be other causes for them feeling unwell.

divider single cat paw oct 2024What 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.1

Feline health problems that antibiotics can be used to treat include:
  • Respiratory infections
  • Urinary tract infections
  • Skin infections
  • Wounds
  • Gastrointestinal infections

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.

cat examined by Vets
Image By: 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 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

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 Potential 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 a veterinarian if they do.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content for PangoVet2 save money

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


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 during and 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 nausea and loss of appetite, which can cause more problems if your cat refuses to eat.

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

divider cat faces 2 oct 2024

Interaction of Antibiotics 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. A 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, may interact with:

  • Methotrexate
  • Probenecid
  • Warfarin
  • Bacteriostatics2
Veterinarian at vet clinic giving injection to a longhair cat
Image Credit: Tom Wang, Shutterstock

What Are Alternatives to Antibiotics?

The recognized side effects of antibiotics have led to some cat owners seeking alternative methods of treating infections, but this may not always be possible. 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 to complement the antibiotics. In some cases they may be sufficient to treat some mild cases of superficial skin infections, however, most infections will still require a course of antibiotics. If your cat is allergic to a certain antibiotic, the vet will prescribe a different one often based on culture and susceptibility testing.

Additional treatments may include:

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

divider cats oct 2024

Final Thoughts

Antibiotics are often necessary to help your cat’s immune system when they’re fighting a bacterial infection, but they have their potential downsides. Some of the recognized side effects include allergic reactions, diarrhea, lack of appetite, nausea, and vomiting. While sleepiness is a side effect, most of these adverse effects are not very common and depend on how your cat reacts to the medication.


Featured Image Credit: Africa Studio, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.

How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

How to Tell if Your Cat Is Depressed: 9 Vet-Reviewed Signs to Look For

Although cats have a reputation for being aloof, they can actually feel a range of emotions. When a cat experiences significant changes in...

Wysong Cat Food Review of 2025: Recalls, Pros & Cons

Review Summary Wysong was founded in 1979 by Dr. Wysong and manufactures holistic pet food. It claims that all its food has been...

How Much Playtime Do Cats Need? Why It’s Crucial for Your Cat’s Health (Vet-Verified)

Cats need to play and move around daily to stay healthy. They can play with you, with other pets in your home, or...

2 Cats in China Are Rescued From the Meat Trade

Editor’s note: The idea of eating cats and dogs is disturbing to those of us who see them as companion animals. Though the...

More related

Ocelot vs Savannah Cat: How Are They Different? (With Pictures)

The Ocelot and Savannah Cat share several similarities; both cats have a black spotted coat and a tan color. Both are very energetic...

13 DIY Felt Cat Toy Plans You Can Make Today (With Instructions)

Felines love to play (at least when they aren’t sleeping), so those of us with cats typically end up buying them piles of...

10 Most Popular Vet Apps for Your Pet (2025 Update)

Pet apps have become all too familiar with the modern pet parent. With more and more people seeking virtual pet care services, we’ve...

Can A Cat And A Newborn Interact Safely? How to Prepare & Safety Risks

If you have a cat and are expecting a baby, you might wonder if allowing your pet and your newborn to hang out...

Keep reading

How Long Does It Take to Spay a Cat? Surgery Details Revealed

Millions of people take their cats to the vet each year to have the vet spay them. It’s a routine surgery, in general veterinarians can spend between 15 to 20 minutes on the procedure. That’s why we came up with...

cat neutered

Do Cats Have Taste Buds? Vet-Verified Facts & FAQ

Cats have sharp senses, and their senses of smell, hearing, and vision are incredibly developed. Still, some of their other senses, like the sense of taste, are not as strong. If you’ve ever wondered if cats have taste buds, the...

persian cat eating dry food

How to Be a Good Cat Owner: 10 Vet-Reviewed Tips

There’s a big difference between having a cat and being a good pet parent. Being a good cat owner is more than just putting out food and buying your cat a bed. So, whether you have a special feline in...

white cat with the owner

Can Cats Eat Cheesecake? Vet-Verified Nutritional Facts

Cheesecake is a delicious, special treat for many people that is often reserved for special occasions. As cat lovers, we all want to share our special occasions with our cats, which means you may have thought about sharing some of...

Can Cats Eat Cheesecake

Can Cats Eat Sage? Vet-Reviewed Nutritional Facts & FAQ

If you have a cat and like plants, you know how hard it is to keep your furry friend away from them. We try our hardest to shoo them away, but our cats always seem one step ahead of us....

Can Cats Eat Sage

Can Cats Eat Walnuts? Vet Approved Facts & FAQ

As a pet owner, you may already know that nuts are the arch-enemy of dogs. Cats aren’t the biggest fans of them either. However, felines, unlike dogs, don’t need to be rushed to your local emergency vet practice if they...

Can Cats Eat Walnuts

Why Is My Cat Leaking Poop? 5 Vet-Reviewed Reasons & Treatment

We do our best to keep our cats as healthy as possible, so it can be quite alarming when they start exhibiting unusual clinical signs. If you have noticed that your cat has begun leaking poop, also referred to as...

cat pooping in a yellow litter box

Can Cats Eat Sauerkraut? Vet-Approved Facts & FAQ

Sauerkraut is a food that generates strong opinions. Most people fall into one of two categories with sauerkraut: They either hate it or love it. Very few people fall in the middle. It’s a food with a strong, distinct taste...

Can Cats Eat Sauerkraut