Why Is My Kitten Lethargic?

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Most cats sleep throughout the day and become more active at dusk and dawn. They also tend to hide their illnesses from us and may not show pain the same way a human would. However, if your cat is spending more time sleeping than usual, ultimately acting lethargic, it could indicate a health problem. Lethargy is not normal, but it might be difficult to tell if your kitten is lethargic or they're just napping during the day. 

Knowing if your kitten is acting lethargic can help you determine when to consult your vet. Cats can be lethargic for many reasons, ranging from parasites to depression, so the cause of your kitten's lethargy will ultimately impact the way they're treated. So, if you're wondering, "Why is my cat suddenly lethargic?" you've come to the right place. This article will discuss what lethargy is, signs your cat is lethargic, why they might be lethargic, and what to do about it. 

What Is Lethargy?

Lethargy is a decrease in a cat's normal activity level and alertness.1 If your cat is lethargic, they will sleep more and be less interested in their favorite activities like playing with toys or watching birds from the window. Ultimately, when pets don't feel well, they try to nap it off. A cat who is sick or in pain will sleep like humans do because their bodies are telling them something's not right. Many illnesses can also make cats more tired, causing lethargy and weakness. Lethargy is ultimately their body's way of trying to treat their illness by conserving energy. 

Lethargy in cats is similar to sleepiness because they both result in your cat napping. However, sleepiness wears off, and your cat typically goes back to their normal activities after waking up from a nap. On the other hand, lethargy is more long-term and can prevent your cat from enjoying playtime or other activities. While lethargic cats sleep more often, they will continue to be lethargic until the cause is treated. 

Signs your kitten is lethargic

Signs Your Kitten Is Lethargic

As we've discussed, lethargy is not the same as tiredness. Instead, it may accompany other symptoms, including:

1. Lack Of Energy

Lethargy is a complete lack of energy in cats that can prevent them from engaging in their regular activities. For example, if your cat normally wakes up around dusk to play and "hunt," but they suddenly don't, they might be lethargic. 

2. Excessive Sleepiness

Cats who are lethargic sleep more because it's their body's natural way of conserving energy to fight off infection or illness. Since cats don't have the energy to enjoy themselves, they'll choose to sleep instead. Lethargy may also accompany symptoms like weakness, depending on the cause, that can make your cat sleep more because there's nothing else to do. 

3. Lack Of Interest In Surroundings

Lethargic cats have a general lack of interest in their surroundings because they don't have the energy to play, scratch, or even stare out the window. They may stop grooming themselves, lose interest in playtime, or even begin hiding to get away from the normal hustle and bustle of the household. 

4. Accompanying Signs Of Illness

Since lethargy is a sign of illness, your cat may have accompanying side effects of whatever is making them sick, including fever, heavy breathing, and vomiting. These are considered severe side effects, and your cat should have treatment immediately if they start vomiting, stop eating, and are lethargic. 

If your kitten is acting lethargic, take them to a vet immediately. Lethargy in kittens is not normal because they shouldn't have diseases that make them lethargic.

Common Causes Of Lethargy In Cats

There are many causes of lethargy in cats, ranging from severe illness to old age and stress. The only way to know why your cat is lethargic is to visit the vet for a diagnosis. 

If your cat appears to be lethargic for more than 24 hours, take them to the vet for examination because it could indicate a serious illness. Cats that are extremely lethargic, weak, or won't eat, should be examined by a vet immediately.2 Are you wondering, "why is your kitten lethargic?" Some common causes of lethargy in cats include:

Poor Diet

Cats that aren't getting enough nutrients from their diet can become lethargic because their bodies aren't getting the fuel they need to be active. Since kittens need a different balance of nutrients than cats, never feed your kitten cat food until they become an adult. Kitten food has more nutrients for young cats and more calories since growing bodies require more fuel. If you feed your kitten adult cat food, they can become lethargic because they're not able to get the fuel they need to grow and play. 

Cat diet and nutrition are important to their development and health and wellness, so always ensure you're feeding your cat a proper diet based on their age and weight. 

Parasitic Infection

Infections can make your cat feel weaker because they feed on your cat's blood. For example, hookworms can cause anemia in cats, leading to lethargy and weakness. If your cat has a parasitic infection, they may become lethargic and experience GI issues like vomiting and diarrhea

Parasites do not go away on their own and must be treated by a vet. If your cat is showing signs of illness or you see a worm in their feces, call your vet immediately for treatment. The infection should clear up in a few days with deworming medication that kills larvae and adult worms. 

Causes of lethargy in kittens

Stress And Depression

Stress and depression can cause your cat to sleep more during the day and have a change in their behavior. Instead of doing activities they normally enjoy, cats can become withdrawn and hide to manage their stress independently.3 Stressed cats may also engage in destructive behaviors like scratching the furniture or walls, but this isn't always the case. 

Of course, there are many reasons why a cat might get stressed, including a new person or pet, moving homes, or even something as small as moving their litter box to a new location. Cats can get stressed just as easily as humans and other pets and cause them to become more lethargic. Other signs of stress in cats include:

  • Hiding
  • Aggression
  • Destructive behavior
  • Growling and hissing
  • Eating or drinking less
  • Stiff posture3

Luckily, there are plenty of ways to manage your cat's stress to help them feel better, including leaving them alone to self-soothe, introducing them to new people and pets slowly, and keeping their regular routine no matter what. 

Old Age

Senior cats are naturally more tired and less energetic than kittens and healthy adult cats. However, healthy senior cats shouldn't be lethargic. Even though they might not be able to move as well, they should still be alert. In addition, senior cats may suffer from age-related health conditions like arthritis, joint disease, and other illnesses like heart conditions and cancer that can cause them to become lethargic.

If you notice that your senior cat is sleeping more than usual or isn't enjoying their regular activities, consult a vet. The older your cat is, the more prone they are to fatal illnesses, so they should receive treatment as soon as possible. 


Cats who can't move without feeling pain may withdraw and avoid their normal activities to sleep instead. Lethargy due to pain is quite common because cats don't experience pain when sleeping, so they'll try to sleep to avoid movement that causes them any discomfort. 

If your cat is experiencing pain, they might meow excessively or become aggressive when you try to touch them where it hurts. If you believe your cat is experiencing pain, take them to the vet as soon as possible. There are many causes of pain in cats, including poisoning, ingesting a foreign object, and disease. 


Many types of diseases in cats cause lethargy, among other symptoms. Everything from heart disease to liver and kidney disease can make your cat more lethargic while their body tries to fight the infection. Cancer, most common in older cats, can also cause lethargy. 

As we've already mentioned, lethargy doesn't happen to healthy cats, so if your cat has a general lack of interest in regular activities or they're sleeping more than usual, take them to the vet as soon as possible. Diagnosing a disease early can improve their chances of a successful treatment, so there's no reason to put off getting your cat help if they're sick. 

Pet owner comforting their lethargic kitten

Next Steps

The treatment for your cat's lethargy will depend on the cause. For example, if your cat is lethargic due to disease, your vet will try to treat the underlying disease to relieve the symptoms. Even though lethargy isn't normal, it can be expected in some cases. For example, cats may get lethargic after getting vaccinated or as they approach old age. That being said, kittens should never be lethargic; they should have tons of energy to run and play, so if your kitten is lethargic, take them to the vet immediately. 

Since there are so many causes of lethargy in cats, you can't treat them alone. Dutch makes it easy to get your cat the care they need from the comfort of your own home. Whether you need cat allergy treatment or medication to reduce stress levels, Dutch has you covered. Our team of professional vets can help you get the answers you need to ensure your cat's health. 



  1. Jennifer Coates, DVM. “Why Is My Cat Lethargic?” PetMD, PetMD, 11 Aug. 2022, https://www.petmd.com/cat/symptoms/why-my-cat-lethargic.

  2. “Low Energy (Lethargy) in Cats.” PDSA, https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/symptoms/low-energy-lethargy-in-cats.

  3. “Spotting Signs of Cat Stress - How to Care.” Cats Protection, https://www.cats.org.uk/help-and-advice/health/cat-stress.

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