How Long Do Steroid Shots Last in Cats? A Vet Explains

Corticosteroids (a.k.a. “steroids) are common but controversial medications used in the veterinary treatment of cats. Some people think steroids are a good option for treating many cat diseases. On the other end of the spectrum are vets and cat owners who believe steroids should rarely be used for cats. 

Are steroids good or bad for cats? They are both good and bad. Steroids can be life-saving when used judiciously in the right cases. The same drugs can be deadly when they’re overused or applied recklessly.

If your cat has asthma, allergies or eosinophilic granuloma complex your vet will probably recommend steroids at some point. Steroid injections are the easiest way to get the medicine into a cat since most of them hate taking oral medication

There are several different forms of injectable steroids for cats. The most common formulas are dexamethasone sodium phosphate, prednisolone acetate (Meticortelone Acetate®), triamcinolone (Vetalog®), and methylprednisolone acetate (Dep-Medrol®). See the table below for more detail on these medications and a few other injectable steroids used for cats.

Uses for Steroid Shots in Cats

Corticosteroid injections can treat inflammation and immune-mediated disease in felines. Some of the specific conditions treated include:

Yellow tabby cat getting a shot (how long do steroid shots last in cats)
Steroid shots can treat many diseases in cats.

How Long Does a Steroid Shot Last in a Cat? 

The length of time a steroid shot lasts in a cat will depend on the specific steroid preparation and the individual cat’s metabolism. The table below shows the approximate duration of action for the three most common injectable steroids used in cats. 

Corticosteroid TypeDuration of Action
Prednisolone succinate1-2 days
Dexamethasone sodium phosphate3-5 days
Prednisolone acetate5-7 days
Triamcinolone acetate7-14 days
Methylprednisolone acetate30-90 days

How Often Can My Cat Get a Steroid Shot? 

The frequency of steroid injections varies depending on the specific situation. Severe, acute conditions like immune-mediated anemia usually require more frequent administration of steroid shots. A very sick cat may need an injection every few days, depending on which type of steroid is used. 

Milder, chronic conditions like feline asthma may require an injection every 2-4 weeks during flares of the disease. 

Veterinarians try to use other treatments to minimize the need for repeated steroid shots for allergic and asthmatic cats. Cats with asthma often benefit from inhaled steroids and topical steroids can help skin allergies.  

How Does a Steroid Shot Affect a Cat? 

Corticosteroid medications are synthetic versions of the hormones produced naturally in a cat’s body. These drugs have many physiological effects including 

  • Altered fat metabolism
  • Increased protein breakdown
  • Insulin antagonism
  • Suppressed inflammation
  • Suppressed immune system function (at high doses)
  • Altered electrolyte balance

As a cat owner, you might notice common steroid side effects including increased thirst, increased appetite, increased urination and occasionally diarrhea. Your cat may gain weight when they take steroids for a longer time.

The most common use of steroids in cats is the suppression of inflammation associated with feline asthma and allergic skin conditions. When used correctly, steroids can improve a cat’s quality of life without causing significant side effects. 

The use of steroids in cats can be a delicate balancing act since they are quite sensitive to this class of drugs. 

Can a Steroid Shot Kill a Cat? 

A steroid shot can kill a cat if they have a pre-existing health condition that makes them susceptible to the side effects of steroids. Corticosteroids can also contribute to death if the dosage is too high or if the medication is given for a long time (months to years).

When it comes to cats and steroids, I’ve seen two deadly types of situations. One happens suddenly and the other has a slow onset. 

The sudden deadly situation occurs when steroids are given to a cat with heart disease. Some steroids cause extracellular hyperglycemia which increases a cat’s plasma volume, putting more stress on the heart. A cat on the verge of heart failure could be pushed over the edge after a steroid shot. 

The other deadly reaction to steroids happens due to diabetes mellitus. Corticosteroids decrease the ability of insulin to move glucose from the bloodstream to the inside of cells. Feline diabetes occurs when glucose stays in the blood instead of getting into cells to provide energy. 

I’ve seen cats develop diabetes after being given long-acting steroid injections like Depo-Medrol. Sometimes the condition is reversible, but not always. 

Oral steroid medication can also lead to these deadly problems but it’s more likely to occur with long-acting injections. Cats taking oral medication can stop taking the meds as soon as the adverse effects are noticed. But once a long-acting steroid injection is given, there is nothing your vet can do to reverse the effects. 

How Long Does It Take for a Steroid Shot to Work on a Cat? 

Most cats have an improvement in symptoms within 24-48 hours of getting a steroid injection. It depends on the condition being treated and the type of steroid administered. 

Cats with asthma and skin allergy symptoms often feel better within 12-24 hours after a steroid injection. If your cat is no better 3-4 days after getting a steroid shot, contact your vet. They may prescribe a different treatment or recommend further testing to better understand your cat’s condition. 

Are Steroid Shots Bad for Cats? 

Steroid shots are both good and bad for cats. Good when used judiciously in the right cases and bad when used excessively without a proper diagnosis. 

The effects of a steroid shot will vary depending on the cat’s health condition. Steroid shots are not considered to be bad in all situations. Steroid medications are powerful tools used to treat specific health conditions in cats. Any tool that is used improperly can cause damage.

Advances in veterinary medicine have produced safer options for treating inflammation in cats these days. Therefore, steroids shots are used less frequently now than they were 20 years ago. 


Steroid shots in cats can last from one to 90 days, depending on the drug preparation. A  decrease in a cat’s disease symptoms is usually apparent within 1-3 days after getting the injection. Veterinarians are cautious about giving cats steroid shots because they can cause serious side effects.  

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Ployngam, T., Tobias, A. H., Smith, S. A., Torres, S. M., & Ross, S. J. (2006). Hemodynamic effects of methylprednisolone acetate administration in cats. American journal of veterinary research, 67(4), 583-587.