# Cat Not Sleeping After Zorbium? What to Expect If your cat is not sleeping after Zorbium, you are likely seeing a real and recognized reaction. Zorbium is a long-acting buprenorphine formulation, and while many cats become sleepy and calm, some become restless, vocal, or unusually alert instead. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Zorbium is a long-acting injectable buprenorphine used for pain control after surgery in cats. - Sleepiness is the expected effect, but restlessness, pacing, and unusual alertness can happen too. - The medication is given by your veterinarian, usually as a single injection under the skin. - Do not give your cat any additional sedatives, pain medications, or human drugs to help it sleep. - Call your veterinarian if restlessness is severe, lasts more than a day or two, or comes with trouble breathing, vomiting, or a racing heart. ## What Is Zorbium and Why Did My Cat Get It? Zorbium is a buprenorphine product formulated to release slowly over several days. Veterinarians use it to control pain after surgery, most often after spays, neuters, and other procedures. Buprenorphine is an opioid analgesic, which means it works on the same pain pathways that opioids act on in people. Your veterinarian may also use it when a cat has an injury or a painful condition and giving pills at home is not practical. Because it is a single injection, it removes the daily struggle of pilling a cat that is already sore and stressed. Buprenorphine is well studied in cats. In one trial of feral cats undergoing spay surgery, a single subcutaneous dose of buprenorphine helped keep postoperative pain scores below the level where rescue pain relief was needed [1]. That is the goal: enough pain control to keep your cat comfortable without constant redosing. ## How Buprenorphine Works in Cats Buprenorphine binds to opioid receptors in the brain and spinal cord. It is a partial agonist, which means it activates those receptors but with a ceiling effect. That ceiling is part of why it is considered relatively safe compared with full opioid agonists. The drug is metabolized in the liver and cleared slowly in cats. That slow clearance is why a single dose can last for days. It is also why side effects, when they happen, can linger longer than you might expect from a typical pain injection. Pain itself can keep a cat awake and agitated. Untreated or undertreated pain triggers a stress response, including release of the body's own catecholamines, which can raise heart rate and blood pressure [2]. So if your cat is restless, it is worth asking whether pain, the drug, or both are involved. ## Dosing Basics: Who Decides and How It Is Given Your veterinarian decides the dose. It is calculated from your cat's body weight, overall health, and the procedure or condition being treated. Do not adjust, repeat, or supplement the dose on your own. Zorbium is given as an injection, typically under the skin, in the clinic. You will not be sent home with a vial to inject. That means there is no at-home dosing schedule and no missed dose to worry about in the usual sense. If your cat was sent home with other pain medication, follow the written instructions exactly. Do not add anything extra because your cat seems uncomfortable or awake. Combining pain medications without veterinary guidance can cause serious harm. If you think a dose was missed or your cat did not receive the full injection, call the clinic that treated your cat. Only they know what was given and when. ## Common and Serious Side Effects Most cats tolerate buprenorphine well. The table below covers what owners most often report and how to respond. | Side effect | How common or serious | What to do | |---|---|---| | Sleepiness, sedation, quiet behavior | Common and expected | Let your cat rest in a quiet, warm spot. Offer food and water nearby. | | Restlessness, pacing, night waking | Uncommon but reported | Keep the environment calm and dim. Call your vet if it is severe or lasts beyond a day or two. | | Reduced appetite | Common in the first day or two | Offer small, smelly meals. Call your vet if your cat eats nothing for more than 24 hours. | | Vomiting or drooling | Uncommon | A little drooling can happen with nausea. See our guide on [cat drooling after medication](/knowledge/veterinary-medicine/pet-medication-guide/cat-drooling-after-medication). Call your vet if vomiting repeats. | | Slow breathing | Rare but serious | Seek emergency care right away. | | Extreme agitation, tremors, or a racing heart | Rare but serious | Treat as an emergency. Call your vet or an emergency clinic now. | | Constipation | Uncommon | Encourage water. See [cat constipation after surgery](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-constipation-after-surgery) for practical steps. | Some cats also become constipated after surgery for reasons unrelated to the drug, including reduced activity and dehydration. If your cat has not passed stool for a couple of days and seems uncomfortable, that deserves a call. ## Why Some Cats Are Restless Instead of Sleepy This is the question most owners ask, and the honest answer is that the exact reason is not fully established in veterinary research. Several factors likely play a role: - **Individual response.** Cats vary widely in how they respond to opioids. Some become sedated, some become dysphoric, which means agitated or unsettled. - **Pain breakthrough.** If the pain control is not complete, your cat may be awake because it hurts. Pain and restlessness often look similar. - **Stress from the clinic visit.** A car ride, a strange room, and handling can leave a cat wired for hours. - **Other drugs given at the same time.** Anesthetic and sedative drugs used during the procedure can interact with recovery behavior. In cats sedated with dexmedetomidine, prior gabapentin changed sedation scores and recovery patterns [3]. Your cat's full drug protocol matters. - **Underlying heart or health issues.** Some cats develop heart changes after anesthesia and surgery, and stress responses can contribute [2]. This is uncommon but worth knowing. If your cat is pacing, crying, or staring at walls, do not punish it and do not try to force it to sleep. Dim the lights, reduce noise, and give it a safe, quiet room with a litter box, water, and a soft bed. ## Zorbium Side Effects: What to Watch For Most side effects are mild and fade as the drug clears. The ones that matter most are breathing changes, severe agitation, and repeated vomiting. Check your cat's breathing while it is resting. Normal resting breathing in a calm cat is quiet and easy to count. If your cat is breathing fast at rest, breathing with its mouth open, or its gums look pale or blue, that is an emergency. Watch for these too: - Repeated vomiting or dry heaving. See [my cat keeps dry heaving but nothing comes out](/knowledge/veterinary-medicine/clinical-methods/my-cat-keeps-dry-heaving-but-nothing-comes-out). - Not eating or drinking. See [cat not eating: how long before it's an emergency](/knowledge/veterinary-medicine/vet-visit-decisions/cat-not-eating-emergency). - Not eating but otherwise acting normal. See [cat not eating but acting normal](/knowledge/veterinary-medicine/vet-visit-decisions/cat-not-eating-but-acting-normal). - Tremors, twitching, or a body temperature that feels very warm or very cool. ## Who Should Not Receive Zorbium and What Interacts With It Buprenorphine is generally avoided or used with extra caution in cats with certain conditions. Your veterinarian weighs the risks and benefits for your individual cat. Cats that may not be good candidates include: - Cats with significant liver disease, since the drug is cleared by the liver. - Cats with head injuries or increased pressure inside the skull. - Cats that are very young, very old, or very frail. - Cats already receiving other opioids or sedatives. Drug interactions matter. Buprenorphine combined with other sedatives, anesthetics, or opioid pain medications can deepen sedation and slow breathing. In one study, adding dexmedetomidine to a local anesthetic block reduced the amount of fentanyl needed during surgery in cats [4]. That shows how layered pain protocols work, and it also shows why your veterinarian needs the full picture of what your cat received. Tell your veterinarian about every medication, supplement, and topical product your cat gets, including flea and tick products. ## Overdose and When to Call for Help An overdose is unlikely with Zorbium because it is given in the clinic by a professional. Still, problems can happen if your cat receives additional opioids or sedatives at home. Signs of too much opioid effect include: - Breathing that is very slow, shallow, or hard to see - Extreme sleepiness that you cannot rouse your cat from - Pinpoint pupils - Cold body temperature - Collapse If you see any of these, call your veterinarian or an emergency veterinary clinic immediately. If your regular clinic is closed, go to the nearest 24-hour emergency hospital. For suspected poisoning or accidental exposure to any medication, contact the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661. These services may charge a consultation fee. Do not wait to see if things improve on their own when breathing is involved. ## Limitations and When to Contact a Veterinarian This article cannot tell you what is happening with your specific cat. Only a veterinarian who examines your cat can do that. **Call the same day if:** - Your cat has been restless or pacing for more than 24 hours - Your cat has not eaten in 24 hours - Your cat is vomiting more than once or twice - Your cat has not urinated since coming home - You are unsure whether the behavior is pain or drug effect **Go to an emergency clinic now if:** - Breathing is fast, labored, or your cat is open-mouth breathing - Gums are pale, white, or blue - Your cat collapses or cannot be woken - There are tremors, seizures, or severe agitation that could lead to injury - Your cat's body temperature feels very hot or very cold **Schedule a routine visit if:** - Mild restlessness is slowly improving over a few days - Appetite is returning but still lower than normal - You want a pain plan review for future procedures ## Frequently Asked Questions ### How long does restlessness after Zorbium usually last? It varies by cat, and there is no single number that fits every case. Because the injection releases slowly, effects can last for several days. If your cat is still pacing or unable to settle after a day or two, call your veterinarian. ### Is it safe to give my cat something to help it sleep? No. Do not give any sedative, antihistamine, or human sleep aid to your cat. These can combine with buprenorphine and cause dangerous breathing problems. Call your veterinarian instead, and they can advise on safe options. ### Can I give my cat more pain medication if it seems uncomfortable? No. Never add pain medication on your own. Your cat may already have long-acting pain control on board, and stacking drugs can cause an overdose. Call your veterinarian, who can assess whether the dose or plan needs to change. ### Does Zorbium cause sleepiness or restlessness more often? Sleepiness is the more typical response, and many cats sleep through the first day or two. Restlessness is less common but well recognized by veterinarians. If your cat is restless, that does not automatically mean something is wrong, but it should be monitored. ### Should I keep my cat confined after Zorbium? Yes, keep your cat indoors and in a quiet, safe space for at least the first day or two. A cat that is sedated or disoriented can fall, get stuck, or injure itself. Limit stairs, jumping, and rough play until your cat is fully back to normal. ## Related Articles - [Cat Not Eating But Acting Normal: How Long Can You Wait?](/knowledge/veterinary-medicine/vet-visit-decisions/cat-not-eating-but-acting-normal) - [What to Do If Your Cat Is Drooling After Taking Medication](/knowledge/veterinary-medicine/pet-medication-guide/cat-drooling-after-medication) - [Cat Not Eating: How Long Before It's an Emergency?](/knowledge/veterinary-medicine/vet-visit-decisions/cat-not-eating-emergency) - [Cat Constipation After Surgery: What to Expect and How to Help](/knowledge/veterinary-medicine/digestive-and-urinary-care/cat-constipation-after-surgery) - [My Cat Keeps Dry Heaving But Nothing Comes Out](/knowledge/veterinary-medicine/clinical-methods/my-cat-keeps-dry-heaving-but-nothing-comes-out) - [Cat Lethargy](/knowledge/veterinary-medicine/symptom-guides/cat-lethargy) - [Cat Not Eating After Zorbium: What Owners Should Know](/knowledge/veterinary-medicine/pet-medication-guide/cat-not-eating-after-zorbium) - [Cat Diarrhea After Zorbium: What to Do](/knowledge/veterinary-medicine/pet-medication-guide/cat-diarrhea-after-zorbium) - [Cat Not Sleeping After Anesthesia: What's Normal?](/knowledge/veterinary-medicine/emergency-and-first-aid/cat-not-sleeping-after-anesthesia) ## References 1. [Evaluation of buprenorphine as optimisation of postoperative analgesia in feral cats undergoing ovariohysterectomy under field conditions](https://pubmed.ncbi.nlm.nih.gov/41332342/). The Journal of small animal practice, 2026. 2. [Retrospective Evaluation of Anesthetic-Analgesic Protocols in Cats with and Without Transient Myocardial Thickening Following Gonadectomy](https://pubmed.ncbi.nlm.nih.gov/42450686/). Animals : an open access journal from MDPI, 2026. 3. [Influence of prior administration of gabapentin and integrative practices on sedation scores, physiological parameters, and propofol requirement in cats sedated with dexmedetomidine](https://pubmed.ncbi.nlm.nih.gov/42437608/). Topics in companion animal medicine, 2026. 4. [Intraoperative opioid-sparing effect of a quadratus lumborum block using low-concentration bupivacaine and dexmedetomidine in cats undergoing ovariohysterectomy](https://pubmed.ncbi.nlm.nih.gov/42487432/). Journal of feline medicine and surgery, 2026. ## Further Reading - [American Veterinary Medical Association: First Aid Tips for Pet Owners](https://www.avma.org/resources-tools/pet-owners/emergencycare/first-aid-tips-pet-owners) - [Merck Veterinary Manual: Cat Owners](https://www.merckvetmanual.com/cat-owners) - [Cornell Feline Health Center: Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information)