Cat Aggression Medication: The Types, Dosage, and Side Effects

November 07, 2022
Medically reviewed by James Davis, PharmD
cat aggression medication

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If you are considering medication for your cat's aggression, they are most likely out of control. You have probably tried everything from behavior training to pheromones. You would do anything to bring back balance to your home and do not even want to consider giving up your furry friend.

But is medication the answer?

This blog answers questions on medicating aggressive cats. It answers the crucial questions: what medication does, how medications are used for aggression in cats, and their side effects.

It's important to note that some of these medications can cause seizures. To learn more you can read our article about how to identify seizures in cats.

Benzodiazepines for Cats 

Benzodiazepines (BZDs) are the last resort for your cat. They have strong effects, but cats can become dependent with use. Like their human owners, cats can also adapt to a dose and need more to achieve the same results.
Benzodiazepines work by slowing your cat's central nervous system activity. They start working quickly, and you'll usually see effects on fear and agression can in just a few hours.
One of the more widely used benzodiazepines for cats is diazepam, or Valium. Veterinarians prescribe diazepam for many pets, including cats, dogs, goats, and horses.

Benzodiazepine Side Effects in Cats 

Benzodiazepines have a strong relaxing effect on the control center of the body (the brain!). This means one of the most common side effects of their use is uncontrolled movement.
This relaxing effect also leads to drowsiness, confusion, increased appetite, sleepiness, and weakness. Extreme situations can lead to overdose. This can cause severe side effects include slow heartbeat and difficulty breathing.

Below is an in-depth table of Benzodiazepines, dosages, and side effects.

Medicine Dosage Common Side Effects Severe Side Effects
Alprazolam (Xanax) 0.125-0.25 mg per cat, every 8 to 24 hours Clumsiness, Diarrhea, Gas, Increased Appetite, Sedation, Vomiting Breathing Problems, Facial Swelling, Hives, Seizure, Sudden Diarrhea
Clonazepam (Klonopin, Rivotril) 0.05–0.2 mg/kg, one to three times/day Drooling, Incoordination, Excitement, Sleepiness Sudden Liver Damage (may appear as diarrhea, yellowing of the skin, eyes, or gums, lack of appetite)
Diazepam (Valium, Ducene, Antenex) 0.2–1 mg/kg, three times a day or as needed Aggression, Agitation, Drooling, Increased Appetite, Incoordination, Weakness, Sleepiness hepatic necrosis, Lack of Appetite, Severe Lethargy, Steady Vomiting, Yellowing of the Skin Gums, and Eyes
Lorazepam (Ativan) 0.025–0.08 mg/kg, one to two times/day Aggressive Behavior, Anxiety, Drooling, Increased Appetite, Increased Activity, Sleepiness Depression, Lack of Appetite, Yellowing of the Skin, Gums, or Eyes

Benzodiazepine Toxicity in Cats

These are the overdose signs to watch for if your cat overdoses on benzodiazepines:

  • Aggression
  • Agitation
  • Lack of coordination (ataxia)
  • Nausea
  • Severe sedation
  • Vomiting
  • Muscle tremors
  •  Weakness

Lethal Dose of Benzodiazepine 

Cats that consume a lethal dose of benzodiazepines may suffer from airway collapse and need intubation. If you suspect your cat has taken benzodiazepines they have not been prescribed, or if they've taken more than they should, call your veterinarian or take them to your vet immediately.

Monoamine Oxidase Inhibitors (MAOI) for Cats 

MAOis are more dangerous than many other drugs used for aggression or agitation. This is due to their many drug and food interactions. Foods with high levels of tyramine are very toxic when mixed with MAOIs. Mammals, including cats, use tyramine to regulate blood pressure.
Foods high in tyramine include aged cheeses, cured and processed meats, and others. See a full list from the Mayo Clinic here.
MAOis are drugs that affect the chemical messages made from dopamine. Dopamine is involved in the brain's reward center and several body functions. MAOis can be used to treat cognitive dysfunction in cats. Cognitive dysfunction causes aggression in cats and humans. Treating it helps resolve the aggressive behavior.

Monoamine Oxidase Inhibitors Side Effects in Cats 

Common side effects of MAOIs are associated with stomach issues like diarrhea, lack of appetite, sedation, and vomiting. 

Severe side effects of MAOis in cats are deafness and high serotonin levels if taken in combination with certain foods and medications - see the list linked above.

Here is a deeper dive into the MAOi selegiline, including dosage and side effects.

Medicine Dosage Common Side Effects Sever Side Effects
Selegiline (Anipryl, Eldepryl, l-deprenyl, Selgian, Zelapar) 0.5–1 mg/kg/day (in morning) Aggression, Confusion, Diarrhea, Drooling, Itching, Tiredness Deafness, Panting

Monoamine Oxidase Inhibitors (MAOI) Toxicity 

The overdose signs from MAOIs include:

  • Ataxia
  • Disorientation
  • Hyperventilation
  • Seizures
  • Tremors
  • Unease

You must be aware of interactions between foods and drugs with MAOIs.

A common dangerous combination is combining an MAOIs like selegiline with an SSRI like Prozac. This combination can cause serotonin levels to become too high, which can be deadly.

You should always tell your veterinarian all the medications your cat is taking, especially if they see more than one veterinarian or you change veterinarians.

Lethal Dose of MAOi

The lethal dose of MAOis for dogs and cats is not published, but the toxic human amount is reported to be 4-6 mg/kg. Always follow the directions of your veterinarian when dosing your cat with MAOis. 

Tricyclic Antidepressants (TCAs) for Cats 

Tricyclic antidepressants (TCAs) are used to treat compulsive behavior problems in cats. These can include excessive grooming, reacting negatively to other cats in the household, and anxiety problems.

TCAs work by increasing the neurotransmitters norepinephrine and serotonin: both are involved in regulating emotional reactions. 

Tricyclic Antidepressants Side Effects in Cats 

Tricyclic Antidepressants for cats' side effects include:

  • Blurred vision
  • Dry mouth
  • Constipation
  • Elevated liver enzymes
  • Hives
  • Low blood pressure
  • Weight gain or weight loss

Severe side effects include:

  • Abnormal bleeding
  • Coma
  • Fever
  • Irregular heartbeat (fast)
  • Seizures

Below are some TCAs, dosages, and common and severe side effects.

Medicines Dosage Common Side Effects Severe Side Effects
Amitriptylinoxide (Amioxid, Ambivalon, Equilibrin) 0.5–2 mg/kg/day Constipation, Drowsiness, Dry Mouth, Sedation, Urinary Retention Decreased Blood Cell Counts, Diarrhea, Vomiting
Clomipramine (Anafranil/Clomicalm) 0.25–1 mg/kg/day Confusion, Diarrhea, Increased Thirst Vomiting Convulsions, Elevated Liver Enzymes, Increased Heart Rate
Doxepin (Silenor) 0.5–1 mg/kg, one to two times/day Constipation Decreased Appetite, Diarrhea, Dry Mouth, Straining to Urinate, Vomiting Abnormal Bleeding, Abnormal Heartbeat, Collapse, Coma, Fever, Seizures
Imipramine (Tofranil) 0.5–1 mg/kg, one to two times/day Constipation, Diarrhea, Dry Mouth, Sleepiness Bleeding, Collapse, Fast Heartbeat, Fever, Shaking, Seizures

Tricyclic Antidepressants Toxicity

Many pets have accidentally ingested TCAs. In four years, in the early '90s, over 450 cases of this happening were reported to the IAPIC.

At least 7% of the animals that displayed toxicosis eventually died. Overdoses of TCAs negatively affect the cardiovascular, parasympathetic, and central nervous systems.

Lethal Dose of TCAs  

Animals that eat a lot of this drug (more than 15 mg/kg) may die within 1 or 2 hours if they do not get the proper treatment. If you suspect your cat has gotten into your prescription medications, or if they get more of their medications than the vet prescribed, call your vet or take them to be seen immediately.

Selective Serotonin Reuptake Inhibitors (SSRIs) for Cats 

SSRIs are drugs that are used to treat depression in people and pets. They work by increasing the level of serotonin in the brain. Side effects are generally mild.

Selective Serotonin Reuptake Inhibitors Side Effects for Cats 

SSRI side effects in cats may show in changes in behavior, such as:

  • Anxiety
  • Diarrhea
  • Irritability
  • Lack of appetite
  • Changes in sleep

Severe side effects of SSRIs are:

  • Seizures
  • Serotonin syndrome
  • Excessive vomiting

Below is a deeper view of a few different types of SSRI medicines.

Medicines Dosage Common Side Effects Severe Side Effects
Prozac (Fluoxetine) 0.5–1.5 mg/kg/day Diarrhea, Hypersalivation, Incoordination, Panting, Shaking, Vomiting Aggression, Behavior Changes, Excessive Vomiting, Seizures
Paroxetine (Paxil, Brisdelle) 0.25–1 mg/kg/day Constipation, Diarrhea, Difficulty Urinating, Muscle Twitches, Panting Aggressive Behavior, Over Excitement, Persistent Lack of Appetite
Sertraline (Zoloft) 0.5–1.5 mg/kg/day Agitation, Diarrhea, Dry Skin, Itchiness, Vomiting Abnormal Blood Pressure, Aggression, Coma, High Body Temperature, Seizures

Selective Serotonin Reuptake Inhibitors Toxicity 

Some common symptoms of SSRI toxicity are:

  • Intestinal problems (like diarrhea)
  • Excessive drooling
  • Vomiting 
  • Tremors
  • Seizures
  • Abnormally high body temperature

Lethal Dose of SSRIs

If your cat takes a lethal dose of SSRIs, the effects include:

  • Ataxia
  • High blood pressure
  • Seizures
  • Serotonin syndrome
  • Death

The lethal dose of Fluoxetine is 50mg/kg. 


Natural Aggression Remedies Cats

You are probably looking at all the side effects and wondering if there are natural alternatives. Fortunately, there are options you can choose that have fewer and milder side effects.  

  • Herbs – There are many different types of herbs. Some common forms are tinctures, dried flowers or leaves, essential oils, and teas. However, it is important to note that you should never use essential oils on cats because they can harm their liver. Some cat calming herbs are Catnip, Chamomile, Hops, and Valerian. 
  • Behavior Modification – Through observation, patience, and practice, you now have a good idea of what is causing your cat's aggression. If your cat plays aggressively, you can redirect their attention to stuffed animals or toys. If your cats are not getting along, you can separate them. If fear aggression kicks in when noises or actions around the house startle or scare a cat, you can try to stop or lessen the impact those activities have on the cat. 
  • CBD for Cats - CBD may be helpful for cats because it can calm them down, relieve stress and anxiety, and reduce pain and inflammation. Veterinarians and pet owners often consider CBD for cats because of its relative harmlessness. CBD may be the solution your cat needs to chill out.

biscuits story

Biscuit's Story

Chris Kjolseth | CEO, Relievet

I was unprepared for what would happen to my dog, Biscuit. 

Ever since she was a puppy, she’d spend her days running and playing. I’d take her on walks, to the beach, and dog parks.

Unfortunately, at age 10, she started to limp after trips to the beach. It broke my heart to see her in pain doing what she loved the most. I started feeding her a raw food diet and added high-quality supplements to ensure her nutritional needs were met. Unfortunately, while she loved the food, the limping persisted.

I went to the vet, who looked over Biscuit and said she was likely limping due to joint inflammation. She gave us something to help. This worked well at first. Biscuit was moving around more freely, and was limping less. 

However, a few days later, It was to my absolute shock that she…

Read Her Story
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