Benazepril for Cats: Side Effects and What It Does
By Dr. Zubair Khalid, DVM, MS, PhD ·
Benazepril for cats side effects are usually mild, but some cats develop appetite loss, vomiting, tiredness, or changes in kidney values. Most cats tolerate the drug well when a veterinarian sets the dose and monitors them. This article is educational and is not a substitute for veterinary diagnosis or treatment.
Quick Answer
- Benazepril is an ACE inhibitor, a blood pressure and heart drug your veterinarian may prescribe for heart disease or chronic kidney disease.
- The most common problems owners notice are vomiting, diarrhea, poor appetite, and low energy.
- Serious side effects include very low blood pressure, worsening kidney function, and high potassium levels, which is why blood work matters.
- Never change the dose on your own. Your veterinarian calculates it from your cat's weight and health.
- Call your veterinarian the same day if your cat stops eating, seems weak, or vomits repeatedly.
What Benazepril Is and What Veterinarians Use It For
Benazepril is an angiotensin-converting enzyme inhibitor, often called an ACE inhibitor. It is a human blood pressure medication that veterinarians also prescribe for cats. It comes as a tablet and is given by mouth.
Veterinarians use benazepril for two main problems in cats.
Heart disease. Cats with heart disease often have an overactive renin-angiotensin-aldosterone system, the hormone system that controls blood pressure and fluid balance. Benazepril blocks part of that system. In a large clinical trial of 151 cats with heart disease from various causes, benazepril did not clearly delay treatment failure compared with a placebo [1]. That does not mean the drug never helps. It means the evidence for a strong benefit in feline heart disease is limited, and your veterinarian weighs that when choosing a treatment plan.
Chronic kidney disease. Cats with kidney disease often lose protein in their urine, which can speed up kidney damage. ACE inhibitors like benazepril reduce protein loss in the urine. This is one reason the drug is commonly prescribed for cats with chronic kidney disease [2]. In a study of cats with chronic kidney disease, benazepril was used as the comparison treatment and cats stayed stable over the follow-up period [3].
Some veterinarians also use benazepril for high blood pressure, especially when another condition like kidney disease is driving it. If you are comparing this drug with other common cat medications, our guide to gabapentin side effects in cats covers a very different class of drug used for pain and anxiety.
How Benazepril Works
Your cat's body makes a protein called angiotensin I. An enzyme converts it into angiotensin II, a powerful hormone that squeezes blood vessels tight and tells the body to hold onto salt and water. The result is higher blood pressure and more strain on the heart and kidneys.
Benazepril blocks that enzyme. Less angiotensin II means blood vessels relax, blood pressure drops, and the kidneys filter blood at a lower pressure. That lower pressure is part of why the drug protects the kidneys, and also part of why it can cause problems if the dose is too high or your cat is dehydrated.
Benazepril itself is not the active drug. The liver converts it into benazeprilat, which does the work. This is why the effect builds over days instead of minutes.
Dosing Basics
Only your veterinarian decides the dose. It is based on your cat's weight, kidney values, blood pressure, and other medications. In a clinical trial of cats with heart disease, benazepril was given at 0.5 to 1.0 mg/kg by mouth once daily for up to 2 years [1]. That range is a study dose, not a prescription for your cat. Your veterinarian may choose something different.
Give the tablet with or without food unless your veterinarian says otherwise. Many cats take it hidden in a small amount of wet food or a pill pocket. If your cat spits it out, do not give a second dose unless your veterinarian tells you to.
If you miss a dose, give it when you remember, unless it is almost time for the next one. In that case, skip the missed dose and go back to your normal schedule. Never double up to catch up.
Do not stop benazepril suddenly on your own. Ask your veterinarian first.
Benazepril for Cats Side Effects
Most side effects show up in the first days to weeks, but some develop slowly. The table below separates what owners commonly see from what needs urgent attention.
| Side effect | How common or serious | What to do |
|---|---|---|
| Vomiting | Common, usually mild | Offer small meals. Call your veterinarian if it lasts more than a day or your cat cannot keep water down. |
| Diarrhea | Common, usually mild | Keep water available. Call if it is bloody, frequent, or lasts more than 24 hours. |
| Poor appetite | Common | Try warming food or a favorite wet food. Call if your cat skips two or more meals. |
| Tiredness or weakness | Common early, serious if severe | Mild sleepiness can settle. Sudden collapse or extreme weakness is an emergency. |
| Low blood pressure | Uncommon but serious | Signs include wobbling, cold paws, and collapse. Go to a veterinarian now. |
| Worsening kidney values | Uncommon but serious | Detected on blood work. Your veterinarian monitors for this with periodic testing. |
| High potassium | Uncommon but serious | Detected on blood work. Can cause heart rhythm problems. |
| Cough | Uncommon | Mention it at your next visit. |
In a long-term study of healthy cats given benazepril for 506 days, researchers found no significant changes in cardiac parameters, blood biochemistry, or glomerular filtration rate, and no significant cardiac lesions on histopathology [4]. That is reassuring for healthy cats on the drug, but it does not replace monitoring in cats that already have heart or kidney disease.
Some owners search for benazepril for cats reviews and find stories ranging from "my cat did great for years" to "my cat got sick." Both can be true. Cats with different diseases, different doses, and different monitoring schedules will have different experiences. Your veterinarian's plan matters more than any single review.
If your cat takes other medications, side effects can overlap. Our article on seizure medication side effects in cats explains how to tell drug reactions apart when a cat is on more than one treatment.
Who Should Not Take Benazepril
Benazepril is not right for every cat. Your veterinarian may avoid it or use it with extra caution in cats with:
- Dehydration or ongoing vomiting and diarrhea
- Very low blood pressure
- Certain heart conditions where the drug could drop blood pressure too far
- Pregnancy or nursing
- Known sensitivity to ACE inhibitors
Tell your veterinarian about every medication, supplement, and topical product your cat receives. Some drugs interact with benazepril:
- Diuretics such as furosemide, which can add to blood pressure drops and kidney strain
- Other blood pressure medications, which can stack up
- NSAIDs such as meloxicam, which can stress the kidneys when combined with an ACE inhibitor
- Potassium supplements, which can push potassium too high
- Spironolactone, another potassium-sparing drug
Do not start or stop any of these without talking to your veterinarian first. If your cat also takes allergy medication, our guide to cat allergy medication side effects can help you sort out which drug is causing which symptom.
Overdose and When to Call for Help
An overdose of benazepril can cause a dangerous drop in blood pressure, extreme weakness, wobbling, collapse, and kidney injury. Cats are small, so even one extra tablet can matter.
If you think your cat ate too much benazepril, call your veterinarian or a pet poison control hotline right away. Do not wait for symptoms. Have the tablet strength, the number of tablets, and the time of the dose ready.
If your cat collapses, has trouble breathing, or cannot stand, go to the nearest emergency veterinary hospital immediately.
Limitations and When to Contact a Veterinarian
This article gives general information. Your cat's individual case needs a veterinarian who can examine your cat, run blood work, and adjust treatment.
Call the same day if your cat:
- Refuses food for more than 24 hours
- Vomits more than twice in a day or cannot keep water down
- Has diarrhea that lasts more than a day
- Seems unusually tired, weak, or wobbly
- Develops a cough or breathes faster than normal
Go to an emergency clinic now if your cat:
- Collapses or cannot stand
- Breathes with an open mouth or struggles for air
- Has cold paws, pale gums, or a very slow response to you
- Has a seizure
Bring up at a routine visit:
- Any change in appetite, energy, or drinking
- Any new medication or supplement
- Whether blood work is due
Your veterinarian will usually check kidney values, electrolytes, and blood pressure before starting benazepril and again after a few weeks. Periodic rechecks continue after that. These visits are how problems get caught before they become emergencies.
Frequently Asked Questions
What does benazepril do for cats?
Benazepril blocks an enzyme that tightens blood vessels and raises blood pressure. In cats, veterinarians use it to reduce strain on the heart and to lower protein loss through the kidneys in chronic kidney disease. It does not cure either condition, but it can slow damage and support the heart and kidneys over time.
How long does it take for benazepril to work in cats?
The drug starts working within hours, but the full effect builds over days to weeks. Kidney protein levels and blood pressure are usually rechecked a few weeks after starting. If your cat's condition does not improve, your veterinarian may adjust the dose or add another medication.
Can I give my cat benazepril with food?
Yes, benazepril can be given with or without food unless your veterinarian says otherwise. Many owners hide the tablet in a small amount of wet food or a pill pocket. If your cat eats only part of the food, you may not know how much drug was swallowed, so tell your veterinarian if that happens often.
Is benazepril safe for long-term use in cats?
Many cats take benazepril for months or years under veterinary supervision. A long-term study in healthy cats found no significant heart, blood, or kidney changes over 506 days of treatment [4]. Cats with existing disease still need regular blood work because their kidneys and blood pressure can shift over time.
What should I do if my cat vomits after benazepril?
One mild vomit is usually not an emergency. With
Related Articles
- What Are the Side Effects of Seizure Medication in Cats?
- What Are the Side Effects of Gabapentin for Cats?
- What Are the Side Effects of Apoquel for Cats?
- Cat Allergy Medication Side Effects: What to Watch For
- Cat Urinary Tract Infection Side Effects
- Cat Anxiety Medication: What You Need to Know
- Benazepril for Cats: Uses for CKD and HCM
- Benazepril for Dogs: Side Effects, Dosage and Monitoring
- Mirtazapine for Cats: Side Effects, Dosage, and Safety
References
- Evaluation of benazepril in cats with heart disease in a prospective, randomized, blinded, placebo-controlled clinical trial. Journal of veterinary internal medicine, 2019.
- Why incorporating benazepril into a renal diet may improve treatment efficiency and compliance in cats with chronic kidney disease. Frontiers in veterinary science, 2026.
- The Multicomponent, Multitarget Therapy SUC in Cats with Chronic Kidney Disease: A Multicenter, Prospective, Observational, Nonrandomized Cohort Study. Complementary medicine research, 2020.
- Comparison of the effects of long-term pimobendan and benazepril administration in normal cats. The Journal of veterinary medical science, 2016.