Medications that May Cause Aggression


Always check with your vet if your dog is taking any medication and you are seeing aggression. If your dog is already aggressive, check with your vet whether there is any chance that a side effect could make your dog’s behavior worse.

Some of the benefits of these medications may outweigh the risks. However, it is important to know if aggression is a potential side effect and create a safe environment for those around them.

Some common medications that can contribute to aggression

Prednisone is a steroid used to reduce inflammation. It may be used to treat inflammation, Cancer, Addison’s Disease, and Nervous System Disorders.(1)

Phenobarbital (required medication for seizures), Can both treat aggression related to seizures (2), but can also cause aggression but may be also be prescribed for treating aggression related to seizures.(3, 4)

Corticosteroids are used for a number of different conditions that involve the inflammatory and immune systems such as arthritis, allergies, etc. They should not be stopped abruptly without talking to your vet, especially if your dog has been taking them regularly as it may cause dangerous side effects. If you think they are causing your dog to be aggressive, speak to your vet.(5)

Progestins: Progestins, such as megestrol acetate, are sometimes used to treat certain medical conditions in dogs, but they can also cause aggression.(6)

NSAIDs are also anti-inflammatory medications. They are often prescribed for treating pain.(7, 8, 9, 10). Please note: the references are just some examples of possible aggression as a side effect. Please check the information sheets of any NSAIDS prescribed for your dog.

Aggression is not always listed as the most common side effects of these drugs, and can be prescribed to some dogs that are already aggressive without making their aggression worse, but it is a good idea to be aware that these medications can play a factor in aggression.

Rarely, some medications prescribed for aggression can have the opposite effect, so careful monitoring should be done to determine if the medication is helping or making things worse.

Keep in mind that any dog who is not feeling well may show aggression.  Read more on medical conditions that can contribute to aggression

See Medications used for treating dog aggression


(1) Prednisone Prednisolone, WebMD, Retrieved Feb 28, 2023 from 

(2)Dodman NH, Miczek KA, Knowles K, Thalhammer JG, Shuster L. Phenobarbital-responsive episodic dyscontrol (rage) in dogs. J Am Vet Med Assoc. 1992 Nov 15;201(10):1580-3. PMID: 1289339. Retrieved Feb 28, 2023 from

(3) The Benefits And Risks Of Phenobarbital For Dogs, Kingsdale Animal Hospital Website, Retrieved Feb 28, 2023 from,or%20a%20phenobarbital%20dosage%20change.

(4)Mehta P, Reviewed by Vanessa Farner, DVM, What to Know About Phenobarbital for Dogs, Fetch by WedMD, Retrieved Apr 9, 2024 from

(5)Notari L, Kirton R, Mills DS. Psycho-Behavioural Changes in Dogs Treated with Corticosteroids: A Clinical Behaviour Perspective. Animals (Basel). 2022 Feb 26;12(5):592. doi: 10.3390/ani12050592. PMID: 35268161; PMCID: PMC8909229. Retrieved Feb 28, 2023 from


(7) Client Information Sheet for Metacam (meloxicam oral suspension), Retrieved Feb 28, 2023 from

(8) Client Information Sheet CARPROFEN Chewable Tablets for Osteoarthritis and Post-Surgical Pain, Retrieved Feb 28, 2023 from Retrieved Feb 28, 2023 from

(9)Client Information Sheet Novox® Caplets (carprofen), Retrieved Feb 28, 2023 from

(10) Client Information Sheet Deracoxib Chewable Tablets, Retrieved Feb 28, 2023 from


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