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Puppy Vaccination FAQs: Side Effects

Some animals, like humans, may have allergic reactions after they've had their vaccinations. While the chances are that your puppy will get through its vaccinations without any problems, it's worth knowing what kind of side effects can happen in case your pet is one of the unlucky few to have an adverse reaction to a vaccine.

Warning: Pets with serious illnesses, such as those that affect the immune system, may not be suitable candidates for regular vaccinations. Make sure to tell your vet about any existing conditions before having your puppy vaccinated; your vet can then advise on whether you should go ahead or not.

Common Vaccination Reactions in Puppies

According to Dogs Life magazine, most puppies won't show any adverse reactions after their vaccinations. If they do have side effects, they are usually minor and easy to deal with.

For example, your puppy may be a little listless or clingy for a day or so after it has had the shots. In some cases, your pet may have a small lump on the injection site that may last for a week or more. This shouldn't overly bother your dog, although it may be a little tender to the touch for a few days.

Other Possible Vaccination Side Effects

According to Pets Australia, extremely serious reactions causing severe illnesses or problems are rare, affecting only one in a million pets. Your puppy is more likely to have a minor problem, such as a high temperature, vomiting, itchiness or minor facial swelling than a life-threatening one.

If your pet shows any of these symptoms after a vaccination, contact your vet for advice on how to manage the side effects. For example, you may be told how to monitor and bring down the puppy's temperature if this is a problem. Issues such as itchiness or swelling are likely to need an immediate visit to the clinic where your vet may administer an antihistamine injection to counter the reaction.


  • If you're worried that your puppy may have an adverse reaction to its vaccinations, try to make sure that someone stays with your pet for a few hours after it has had its injections so you can monitor it.
  • If you know that your puppy has had a bad reaction to vaccinations in the past, talk to your vet before it has its next set of injections. Vets may be able to help counter some side effects, such as anaphylactic reactions, by administering antihistamine before vaccinating your dog.