# Ursodiol for Cats: Dosage, Side Effects, and Vomiting Ursodiol for cats dosage is not something you can figure out at home. Your veterinarian calculates it from your cat's weight, the specific liver or gallbladder problem being treated, and how well your cat's liver is working. Most cats take ursodiol once or twice daily as a liquid or capsule, and vomiting is one of the more common reasons owners stop the medication early. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Ursodiol is a bile acid medicine used mainly for liver and gallbladder conditions in cats, including lymphocytic cholangitis, a common inflammatory liver disease in cats [1]. - The dose is always calculated by your veterinarian. There is no safe at-home dose you can guess from a chart. - Ursodiol is usually given with food, once or twice a day, as a capsule, tablet, or compounded liquid. - Vomiting and diarrhea are the side effects owners notice most. Mild stomach upset is common, but repeated vomiting needs a call to your vet. - Never double up on a missed dose. Skip it and get back on schedule unless your vet says otherwise. ## What Ursodiol Is and What Veterinarians Use It For Ursodiol is also called ursodeoxycholic acid, or UDCA. It is a naturally occurring bile acid, and in medicine it is used to change the way bile behaves inside the liver and gallbladder. In cats, veterinarians most often reach for ursodiol when a cat has a liver or biliary problem. The best-studied use in cats is lymphocytic cholangitis, an inflammatory condition of the bile ducts. Cats with this disease often show weight loss, yellowing of the skin and eyes (icterus), loss of appetite, vomiting, and listlessness [1]. Blood work typically shows elevated liver enzymes, elevated bile acids, and high gamma globulin levels [1]. Ursodiol is sometimes used alone and sometimes alongside other medications. In one retrospective study of 26 cats with lymphocytic cholangitis, cats treated with prednisolone lived statistically longer than cats treated with ursodeoxycholic acid alone [1]. A follow-up study looking at liver biopsies found that inflammation decreased more in the prednisolone group, while the number of bile duct cells, progenitor cells, and fibroblasts did not differ between groups, and fibrosis was similar in both groups [2]. That does not mean ursodiol does not help. It means ursodiol is often one part of a treatment plan, and your veterinarian will decide whether it belongs in your cat's plan and what else should be given with it. Ursodiol is also used in cats with other cholestatic liver diseases, gallbladder sludge, and some cases of hepatic lipidosis, though the strength of evidence varies by condition. ## How Ursodiol Works Bile is made in the liver and stored in the gallbladder. It helps digest fat and carries waste out of the body. When bile flow is blocked or bile becomes toxic to liver cells, the liver and bile ducts can become inflamed. Ursodiol works in a few ways. It replaces more toxic bile acids in the bile pool with a gentler one. It helps bile flow more freely through the bile ducts. It also appears to protect liver cells from injury caused by bile acids that build up when flow is poor. In cats with lymphocytic cholangitis, the goal is to reduce the bile acid load on the liver and ease the inflammation in and around the bile ducts. Because ursodiol acts on bile instead of directly killing bacteria or suppressing the immune system, it is usually part of a broader plan that may include diet changes, other medications, and regular monitoring. ## Ursodiol for Cats Dosage: The Basics ### Who decides the dose Your veterinarian decides the dose. Ursodiol dosing in cats depends on body weight, the condition being treated, liver function, and what other medications your cat takes. There is no published feline dose that applies to every pet, so any number you see online should be treated with suspicion. Do not adjust the dose on your own, even if your cat seems better or worse. ### How it is given Ursodiol comes as a human capsule or tablet, and it is often compounded into a flavored liquid or a smaller capsule for cats. It is usually given with food, because food triggers bile release and helps the medicine do its job. If your cat is a picky eater, ask your veterinarian about a compounded liquid or a treat that hides the taste. Some cats take ursodiol well in a pill pocket. Others need it syringed into the side of the mouth. Never crush or open a capsule unless your veterinarian or pharmacist tells you it is safe for that specific product. ### Missed doses 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 continue on schedule. Do not give two doses at once to catch up. If you miss doses often, tell your veterinarian. They may switch to a once-daily version or a different form. ### How long it takes to work Ursodiol is not a fast-acting drug. Liver enzyme changes and clinical improvement can take weeks. Your veterinarian will likely recheck blood work after a set period to see how your cat is responding. ## Ursodiol for Cats Side Effects Most cats tolerate ursodiol well. When side effects happen, they are usually mild and involve the stomach or intestines. Vomiting and diarrhea are the two owners report most often. | Side effect | How common or serious | What to do | |---|---|---| | Vomiting | Common, usually mild | Give with food. If vomiting happens more than once or lasts more than a day, call your vet. | | Diarrhea | Common, usually mild | Keep water available. Call your vet if it lasts more than 24 hours or your cat seems weak. | | Poor appetite | Occasional | Offer favorite foods. Call your vet if your cat refuses food for more than a day. | | Lethargy | Occasional | Note the timing. Call your vet if your cat is hard to wake or will not move normally. | | Yellowing of gums, skin, or eyes | Serious | Call your vet the same day. This can mean bile flow is worse. | | Vomiting blood or black material | Emergency | Go to an emergency clinic now. | If your cat vomits after ursodiol, do not assume the drug is the only cause. Cats vomit for many reasons, including other medications, food changes, and the underlying liver disease itself. If your cat takes more than one medication, it can be hard to tell which one is the trigger. This guide on [Is Your Cat's Medication Causing Vomiting? When to Worry](/knowledge/veterinary-medicine/pet-medication-guide/cat-medication-vomiting-when-worry) walks through how to sort that out. If your cat also takes prednisolone for a liver or immune condition, some of the same stomach upset can come from that drug. This article on [Cat Prednisolone for Allergies: Side Effects and Safe Use](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/cat-prednisolone-allergies) covers what to expect from prednisolone, and many of the same monitoring rules apply. ### Ursodiol for Cats Vomiting: What to Do A single vomit after a dose is usually not an emergency. Try these steps. - Give the next dose with a full meal, not on an empty stomach. - Split the daily dose into two smaller meals if your vet agrees. - Do not stop the medication without calling your vet first. - If your cat vomits two or more times in a day, vomits for more than 24 hours, or stops eating, call your veterinarian. If your cat is vomiting and also has a urinary problem, the cause may be unrelated to ursodiol. This article on [Cat Urinary Tract Infection Side Effects](/knowledge/veterinary-medicine/clinical-methods/cat-urinary-tract-infection-side-effects) explains how urinary issues can cause nausea and vomiting in cats. Your veterinarian may add an antiemetic if vomiting keeps happening. Maropitant, ondansetron, and metoclopramide all reduce vomiting in cats compared with a saline control in controlled studies [3]. In a meta-analysis of controlled feline studies, maropitant reduced the risk of vomiting compared with control, with emesis in 11 of 141 cats given maropitant and 70 of 152 controls [4]. If your cat needs nausea control, your vet will pick the drug and dose that fits your cat. ## Who Should Not Take Ursodiol and What Interacts With It Ursodiol is not right for every cat. Your veterinarian may avoid it or use it with extra caution if your cat has a complete blockage of the bile duct, acute gallbladder infection, or a bile duct rupture. In those cases, surgery or other treatment comes first. Tell your veterinarian about every medication, supplement, and herbal product your cat takes. Ursodiol can interact with other drugs that affect bile or the liver, including some antacids, certain antibiotics, and cholesterol-lowering drugs. Do not start or stop anything without asking your vet first. Cats with other chronic conditions may need dose adjustments. If your cat has kidney disease, heart disease, or diabetes, your veterinarian will factor that in. If your cat takes allergy medication, check this article on [Cat Allergy Medication Side Effects: What to Watch For](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/cat-allergy-medication-side-effects) so you can tell which drug is causing which symptom. Pregnant or nursing cats should only take ursodiol if your veterinarian decides the benefit outweighs the risk. ## Overdose and When to Call for Help If your cat eats more ursodiol than prescribed, call your veterinarian right away. If your regular clinic is closed, call an emergency veterinary hospital or a pet poison control hotline. Have the bottle with you so you can read the strength and the number of pills or milliliters your cat may have taken. Signs that need emergency care include severe vomiting, vomiting blood, collapse, seizures, trouble breathing, or a cat that will not respond to you. Do not wait to see if it passes. For a missed dose, do not double up. For a possible overdose, always call. It is better to make a phone call you did not need than to wait on a problem that gets worse. ## Limitations and When to Contact a Veterinarian Ursodiol is a supportive medication, and it does not fix every liver problem. Some cats need other drugs, diet changes, or procedures. Response varies from cat to cat, and the studies in cats with lymphocytic cholangitis show that outcomes differ depending on which treatment is used [1][2]. Your veterinarian needs to see your cat, not just the lab numbers, to make good decisions. Call your veterinarian the same day if your cat: - Vomits more than twice in 24 hours or vomits for more than a day - Refuses food for more than 24 hours - Has diarrhea that lasts more than a day or contains blood - Seems more tired than usual or hides more than normal - Has yellow gums, skin, or eyes - Has a swollen or painful belly Go to an emergency clinic now if your cat: - Collapses or cannot stand - Has a seizure - Breathes with an open mouth or struggles to breathe - Vomits blood or material that looks like coffee grounds - Has a distended, hard belly and cries when touched Schedule a routine visit if your cat is stable but you have questions about dosing, timing, refills, or how to give the medication. Bring the bottle and a list of everything your cat takes. Every cat is different, and only your veterinarian can decide what is right for yours. ## Frequently Asked Questions ### Can I give my cat ursodiol without a prescription? No. Ursodiol for cats is a prescription medication, and the dose must be calculated by a veterinarian. Giving a human dose or a dose meant for another pet can cause harm. ### Should I stop ursodiol if my cat vomits? Do not stop it on your own. Call your veterinarian first. They may change the timing, split the dose, add an anti-nausea medication, or switch to a different form. ### How long does it take for ursodiol to help my cat? It can take weeks to see changes in appetite, energy, or liver values. Your veterinarian will set a recheck schedule based on your cat's condition. ### Can ursodiol be given with other liver medications? Often yes, but it depends on the other drugs. Tell your veterinarian about everything your cat takes so they can check for interactions. ### What if I forget a dose? Give it when you remember unless the next dose is close. If it is almost time, skip the missed dose and go back to your normal schedule. Never give two doses at once. ## Related Articles - [Cat Urinary Tract Infection Side Effects](/knowledge/veterinary-medicine/clinical-methods/cat-urinary-tract-infection-side-effects) - [Cat Allergy Medication Side Effects: What to Watch For](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/cat-allergy-medication-side-effects) - [Cat Prednisolone for Allergies: Side Effects and Safe Use](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/cat-prednisolone-allergies) - [Is Your Cat's Medication Causing Vomiting? When to Worry](/knowledge/veterinary-medicine/pet-medication-guide/cat-medication-vomiting-when-worry) - [Ondansetron Antiemetic Dose: Nausea Dose for Cancer and Kidney Pets](/knowledge/veterinary-medicine/calculators-clinical-tools/ondansetron-antiemetic-dose-nausea-dose-for-cancer-and-kidney-pets) - [What Are the Side Effects of Gabapentin for Cats?](/knowledge/veterinary-medicine/pet-medication-guide/gabapentin-side-effects-cats) - [Ursodiol for Dogs: Side Effects and Dosing Explained](/knowledge/veterinary-medicine/pet-medication-guide/ursodiol-dogs-side-effects-dosing) - [Ursodiol for Cats With Liver Disease and Pancreatitis](/knowledge/veterinary-medicine/pet-medication-guide/ursodiol-cats-liver-pancreatitis) - [Ursodiol for Cats: Uses and How Long It Takes to Work](/knowledge/veterinary-medicine/pet-medication-guide/ursodiol-cats-uses-how-long) ## References 1. [Retrospective comparison of prednisolone and ursodeoxycholic acid for the treatment of feline lymphocytic cholangitis](https://pubmed.ncbi.nlm.nih.gov/22840210/). Veterinary journal (London, England : 1997), 2013. 2. [A morphological and immunohistochemical study of the effects of prednisolone or ursodeoxycholic acid on liver histology in feline lymphocytic cholangitis](https://pubmed.ncbi.nlm.nih.gov/24496321/). Journal of feline medicine and surgery, 2014. 3. [The Effect of Maropitant, Ondansetron and Metoclopramide on Dexmedetomidine-Induced Vomiting in Cats](https://pubmed.ncbi.nlm.nih.gov/39792081/). Veterinary medicine and science, 2025. 4. [Receptor-Targeted Antiemetic Strategies in Cats: A Systematic Review and Intervention-Specific Meta-Analysis](https://pubmed.ncbi.nlm.nih.gov/42599757/). Veterinary medicine and science, 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)