Why Does My Cat Throw Up After Getting Vaccinated?


Vaccines are an important part of preventative health care for cats. They help protect against serious and potentially fatal diseases like feline distemper, calicivirus, herpesvirus, and rabies. While vaccines are generally safe, some cats may experience side effects like vomiting after receiving a vaccination.

This article provides an overview of common feline vaccines, potential side effects like vomiting, when to be concerned about vomiting post-vaccination, and how to care for a cat exhibiting vaccine reactions. The goal is to help cat owners understand if vomiting after vaccines is normal and what steps to take to monitor the cat’s health and reduce the risk of adverse reactions in the future.

Common Vaccines for Cats

There are several core vaccines that are commonly given to cats to protect against serious and potentially fatal diseases:

Rabies – Rabies is fatal once symptoms appear, so rabies vaccination is critical. It is required by law in most areas. Rabies vaccines provide protection for 1-3 years (Source).

Panleukopenia – Also known as feline distemper, panleukopenia is a severe and contagious viral disease that can be fatal. The vaccine provides 3+ years of protection (Source).

Feline Viral Rhinotracheitis – This contagious upper respiratory infection is caused by feline herpesvirus. The vaccine protects against infection for 1-2 years (Source).

Calicivirus – Another upper respiratory virus that causes oral ulcers and pneumonia. Vaccines provide 1-2 years of protection (Source).

Side Effects of Vaccines

It’s common for cats to experience minor side effects from vaccines. According to Clark Road Animal Clinic, the most typical side effects include hives, itching, pain or swelling at the injection site, vomiting, diarrhea, and lethargy. The Cats.com article also notes that facial swelling and difficulty breathing are potential side effects.

The most common side effects tend to be mild pain, fever, and lethargy. These effects are usually temporary, lasting only a day or two as the cat’s immune system responds to the vaccine. Localized pain, swelling, and redness at the injection site are also common and indicate that the cat’s immune system is responding properly. While alarming, these reactions are usually not serious. Most cats tolerate vaccines well and do not experience any side effects.

Vomiting as a Side Effect

Vomiting is a relatively common side effect after vaccination in cats. According to studies, around 10-15% of cats may experience vomiting within 24 hours after vaccination.

There are a few reasons why a cat may vomit after getting their shots:

  • The immune response triggered by the vaccine can cause nausea and vomiting in some cats. The inflammatory response in the body after vaccination leads to the release of cytokines which can stimulate the vomiting reflex.
  • Some cats may get stressed or anxious about going to the vet or getting shots. This stress and release of stress hormones can also stimulate vomiting.
  • Rarely, an allergic reaction to a component of the vaccine can also lead to vomiting.

Overall, vomiting is usually mild and self-limiting after vaccines. It helps to withhold food for a few hours before and after vaccination to reduce stomach upset. Most cats recover within 24 hours without issues. But if vomiting persists for more than a day or is accompanied by lethargy, call your vet.

When Vomiting Occurs

Vomiting is one of the more common side effects after vaccination in cats. It most often occurs within 24 hours after the vaccine is administered. According to VCA Animal Hospitals, vomiting may happen as soon as 30 minutes after the vaccine or up to 24 hours later https://vcahospitals.com/know-your-pet/vaccines-for-cats. The vomiting is usually mild and resolves on its own within a day or two. If your cat vomits immediately after the vaccine, it could be from the stress of the visit to the vet. Cats that vomit a day later are likely reacting to the vaccine components. The vomiting should stop within 48 hours according to PetMD.

Reducing the Risk

There are some steps cat owners can take to help reduce the risk of vomiting and other side effects after vaccines:

  • Give vaccines when kittens are less active – Kittens tend to sleep more during the day, so giving vaccines in the morning can help reduce activity after the shot that may trigger nausea.
  • Proper vaccine administration – Vaccines should be administered under the skin (subcutaneously) in the back of the neck/shoulder area. Injecting in the right location helps minimize irritation.
  • Allow time to monitor after – It’s recommended to wait 15-30 minutes after giving a vaccine to monitor for any immediate reactions.
  • Separate vaccines – Kittens getting multiple vaccines the same day may have more side effects. Separate vaccines 2-4 weeks apart when possible.
  • Avoid stress before/after – Try to minimize stress by keeping the kitten’s schedule consistent and avoiding vet visits for other procedures the day of vaccines.

While vomiting can still occur even with proper care, taking steps to reduce activity, irritation, and stress around the time of vaccination may lower the chances of an upset stomach.

Treating Vomiting

If your cat vomits after getting vaccinated, there are some simple steps you can take at home to help treat the vomiting and make your cat more comfortable:

Withhold food for 6-12 hours after vomiting occurs. This allows the stomach to rest and recover. Don’t leave your cat without food for longer than 12 hours though.[1]

Make sure your cat stays hydrated by providing constant access to fresh, clean water. You can also give an oral rehydration solution such as Pedialyte to replenish lost fluids and electrolytes.[2]

If your cat is showing signs of dehydration like lethargy or dry gums, call your vet right away. They may recommend bringing your cat in for intravenous fluids.

Feed a bland diet of boiled chicken and rice once your cat’s vomiting subsides and their appetite returns. Gradually transition back to their normal food over 2-3 days.

Avoid giving any dairy products or fatty meals, as these can further upset the stomach.

Calling the Vet

If vomiting after vaccination is severe, persistent, or accompanied by other concerning symptoms, it’s important to contact your veterinarian right away. Some signs to watch for that may indicate a more serious reaction include:

  • Repeated vomiting or retching more than 3-4 times in a short period
  • Vomiting that continues beyond 24 hours after vaccination
  • Vomiting along with lethargy, weakness, or loss of appetite
  • Vomiting combined with facial swelling, hives, difficulty breathing, or collapse
  • Bloody vomit or vomit that looks like coffee grounds

According to the Animal Clinic of Woodruff, “Call your veterinarian immediately if you observe any of these symptoms, which may be signs of an allergic reaction:” including severe vomiting or diarrhea (source).

VCA Animal Hospitals also advises contacting your vet promptly for “persistent vomiting or diarrhea” after vaccination (source). It’s always better to err on the side of caution when monitoring your cat after vaccines.

Preventing Dehydration

Dehydration can quickly become dangerous for cats, so it’s important to take steps to prevent it after vaccination vomiting episodes. Some tips include:

  • Offer wet cat food, which has a high moisture content. Kittens especially need the hydration from wet food. Give small, frequent meals if your cat vomited their last meal. (1)
  • Try adding water or low-sodium chicken broth to dry kibble to increase fluid intake. (2)
  • Provide multiple fresh, clean water bowls around the house. Change the water frequently.
  • Consider getting a cat water fountain, which encourages drinking.
  • Monitor your cat’s hydration by gently pinching up the skin over their shoulders. If it snaps back slowly, they could be dehydrated. Check the color of their gums – they should be pink. (3)

Pay close attention after vomiting episodes and take action at the first signs of dehydration. Providing appetizing wet food and broths can help cats get the fluids they need to recover quickly.

When to Vaccinate Again

It’s important to complete the full vaccine series for kittens as recommended by your veterinarian. Kittens need a series of vaccines to help build immunity when they are young and most vulnerable. According to VCA Animal Hospitals, the initial kitten vaccine series is given every 3-4 weeks until 16-20 weeks of age. After completing this initial series, annual booster vaccines help maintain your cat’s immunity.

For adult cats, an annual veterinary visit is recommended to receive booster vaccines as needed. Your vet will determine which specific vaccines your cat requires based on lifestyle factors like indoor/outdoor access. Core vaccines that most adult cats receive annually include: rabies, feline viral rhinotracheitis, calicivirus, and panleukopenia. Staying up-to-date on vaccines protects your cat against serious preventable diseases and minimizes the risk of outbreaks.

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