Cat Not Eating After Zorbium: What Owners Should Know

Name: Cat Not Eating After Zorbium: What Owners Should Know
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Cat not eating after Zorbium is a common and usually temporary side effect of this long-acting pain medication. Most cats return to normal eating and drinking within one to five days as the drug wears off. If your cat stops eating or drinking entirely, or seems sick instead of just sleepy, contact the prescribing veterinarian.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Zorbium is a long-acting buprenorphine solution applied to the skin at the back of the neck for pain control after surgery.
Reduced appetite, reduced drinking, sleepiness, and unsteadiness are expected side effects in many cats.
These effects usually fade over one to five days, but some cats take longer.
A cat that refuses all food and water for more than 24 hours needs veterinary attention.
Never apply a second dose or give oral pain medicine on your own. Call the prescribing vet first.

What Is Zorbium and Why Did My Cat Get It?

Zorbium is a transdermal (through the skin) form of buprenorphine. Buprenorphine is an opioid pain reliever used in cats. The Zorbium formulation is designed to release medication slowly over several days from a single application on the skin.

Veterinarians use it most often after surgery, including spays and neuters. It provides sustained pain relief without the need for repeated injections or daily oral dosing, which is helpful for cats who are difficult to medicate.

Buprenorphine is well established as an effective postoperative analgesic in cats. In one study of feral cats undergoing ovariohysterectomy, subcutaneous buprenorphine given at the end of surgery helped keep postoperative pain scores below intervention thresholds [1]. Zorbium uses the same active drug in a long-acting topical form.

How Zorbium Works

The medication is absorbed through the skin into the bloodstream. Once there, it binds to opioid receptors in the brain and spinal cord, which reduces the perception of pain.

Because absorption is slow and continuous, a single application can provide pain relief for days. This is different from an injection, which peaks quickly and wears off within hours.

The trade-off is that side effects also last longer. A cat who feels sleepy or off their food after an injection may bounce back by evening. After Zorbium, that same drowsiness and appetite loss can stretch across several days.

Dosing Basics: Who Decides and How It Is Given

Your veterinarian calculates the Zorbium dose based on your cat's body weight and overall health. Do not try to estimate or adjust the dose yourself.

Zorbium comes in pre-filled applicators. The vet or technician applies it directly to the skin at the back of the neck, parting the fur so the liquid reaches the skin instead of sitting on the hair. You should not touch or rub the application site, and you should keep children and other pets away from it for the period your vet recommends.

What if a dose is missed or rubbed off?

Zorbium is given in the clinic, so a missed at-home dose is not usually an issue. If you think the medication was rubbed off, washed off, or applied incorrectly, call your veterinarian. Do not apply another dose on your own.

Can I bathe my cat after Zorbium?

Ask your vet when bathing is safe. Water and shampoo can affect how the medication is absorbed, and the timing matters.

Common and Serious Side Effects

Most side effects after Zorbium are mild and self-limiting. Some are more serious and need a call to your vet.

Side effect	How common or serious	What to do
Reduced appetite	Common, usually mild	Offer small amounts of warm, smelly food. Call your vet if your cat eats nothing for 24 hours.
Reduced drinking	Common, usually mild	Offer fresh water in several spots. Call your vet if you see no drinking for 24 hours.
Sleepiness or sedation	Common, usually mild	Let your cat rest in a quiet, warm place. Call if your cat is hard to wake.
Unsteady walking	Common, usually mild	Block stairs and furniture. Call if it lasts more than a day or worsens.
Vomiting	Less common	Call your vet if it happens more than once or lasts more than a day.
Not peeing	Less common but serious	Call your vet the same day. A cat who cannot urinate needs urgent care.
Slow, shallow breathing	Uncommon, serious	This is an emergency. Call your vet or an emergency clinic right away.
Pinpoint pupils, agitation, or vocalizing	Uncommon, serious	Call your vet or an emergency clinic right away.

Cat not eating or drinking after Zorbium

This is the concern owners report most often. Opioids commonly cause nausea and appetite loss in cats, and a long-acting product can stretch that effect out.

Try offering a small amount of a favorite wet food, warmed slightly to boost the aroma. Do not force-feed your cat. Do not switch to a completely new diet during recovery, since sudden diet changes can upset the stomach further.

If your cat is not eating or drinking at all, that is different from eating less. A cat who takes in no food or water for a full day needs to be seen. Cats who stop eating can develop hepatic lipidosis, a serious liver condition. One case report described an 8-year-old cat who presented with a week of anorexia and lethargy and was diagnosed with hepatic lipidosis confirmed by liver aspirate [2]. Early intervention matters.

For more on how long you can safely wait, see Cat Not Eating? When to Worry and What to Do and Cat Not Eating But Acting Normal: How Long Can You Wait?.

Cat not peeing after Zorbium

Reduced drinking can lead to reduced urination. That alone is not usually an emergency if your cat is still producing some urine.

A cat who is straining to urinate, crying out, licking the genital area, or producing no urine at all needs emergency care. This is especially true for male cats, who can develop a urinary blockage. A blocked cat can become critically ill within hours.

If your cat is eating but not producing stool, that is a separate issue. See Cat Not Pooping but Eating Normally: Causes and When to Help.

Vomiting after Zorbium

A single episode of vomiting after anesthesia and pain medication is not unusual. Repeated vomiting, vomiting with a swollen or painful belly, or vomiting yellow fluid when your cat is not eating warrants a call. See Cat Vomiting Yellow Liquid Not Eating.

Who Should Not Receive Zorbium and What Interacts With It

Zorbium is not appropriate for every cat. Your veterinarian will weigh the risks if your cat:

Has liver or kidney disease
Has a history of seizures
Is pregnant, nursing, or intended for breeding
Has known sensitivity to buprenorphine or other opioids
Is very young, very old, or very small

Tell your vet about every medication, supplement, and topical product your cat receives. Other sedatives, tranquilizers, and opioid pain medications can compound the effects of buprenorphine. So can some over-the-counter products.

Do not give your cat any human pain medication. Many common human drugs, including acetaminophen and ibuprofen, are toxic to cats.

Overdose and Poisoning: When to Call for Help

Signs of too much opioid medication in a cat include extreme sedation, difficulty waking, slow or shallow breathing, pinpoint pupils, vomiting, and loss of coordination.

If you see these signs, call your veterinarian or an emergency clinic immediately. If your regular vet is closed, call the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661. Both may charge a consultation fee.

Do not wait to see if your cat improves on their own. Breathing problems from opioid overdose can progress quickly.

Limitations and When to Contact a Veterinarian

Every cat responds differently to medication. Your cat's age, weight, liver function, kidney function, and other health conditions all affect how Zorbium behaves in the body. Individual cases need a veterinarian who can examine your cat and review their full history.

Call the prescribing veterinarian the same day if:

Your cat has eaten nothing for 24 hours
Your cat has drunk nothing for 24 hours
Your cat has not urinated in 24 hours
Vomiting happens more than once
Your cat seems more painful than before the medication
The sedation seems deeper than expected

Go to an emergency clinic right away if:

Your cat is difficult to rouse or will not respond to you
Breathing is slow, shallow, or labored
Your cat is straining to urinate with little or no urine produced
Your cat collapses, has a seizure, or has a body temperature that feels very low
You see severe weakness or inability to stand

Schedule a routine recheck if:

Appetite is improving but still not normal after several days
Your cat is eating and drinking but seems quieter than usual
You have questions about the application site or when bathing is safe

Frequently Asked Questions

How long does appetite loss last after Zorbium?

Most cats start eating again within one to five days as the medication wears off. Some cats take longer, especially if they are older or have other health problems. If your cat has eaten nothing for a full day, call your veterinarian.

Is it normal for my cat to sleep a lot after Zorbium?

Yes, sedation is a common and expected effect. Your cat may sleep more than usual for a few days. Call your vet if your cat is hard to wake or seems unresponsive.

Can I give my cat food or water while they are sedated?

Yes, offer small amounts of food and water, but do not force anything into your cat's mouth. Place water bowls close to where your cat is resting. If your cat will not swallow or seems too drowsy to eat safely, call your vet.

What if my cat is not drinking water after Zorbium?

Reduced drinking is common because the medication can cause drowsiness and mild nausea. Offer fresh water in multiple locations and consider adding a little water to wet food. If your cat has not drunk anything for 24 hours, contact your veterinarian.

Can I use a different pain medication if Zorbium is not working?

Never give another pain medication without talking to your vet first. Combining opioids or adding other drugs can cause dangerous sedation and breathing problems. Your veterinarian can decide whether a different medication or dose adjustment is appropriate for your cat.

References

Evaluation of buprenorphine as optimisation of postoperative analgesia in feral cats undergoing ovariohysterectomy under field conditions. The Journal of small animal practice, 2026.
Effect of Parenteral Amino Acid Composition on Hyperammonemia in a Cat with Hepatic Lipidosis. Journal of the American Animal Hospital Association, 2026.