# Ketoconazole for Dogs: Dosage, Uses, and Side Effects Ketoconazole for dogs dosage is always calculated by your veterinarian from your dog's weight, the type of fungal infection, and your dog's liver health. It is an older oral antifungal that is still used for some skin, ear, and internal fungal infections, but newer drugs have largely replaced it. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Ketoconazole is a prescription antifungal pill, and the dose is decided by your veterinarian, never by a dosing chart you find online. - It works best when given with food, because stomach acid helps the drug absorb. [1][2] - The most common side effects are vomiting, poor appetite, and diarrhea, and they often improve if the pill is given with a meal. - Ketoconazole can raise liver enzymes and interact with many other drugs, so blood work and a full medication list matter. - Newer antifungals such as fluconazole and itraconazole are often preferred because they absorb better and cause fewer stomach problems. [1] ## What Ketoconazole Is and What Veterinarians Use It For Ketoconazole belongs to a family of drugs called azoles. Azoles are among the most widely used antifungals in animals, and they are classified by the number of nitrogen atoms in their core ring. Ketoconazole is an imidazole, which means it has two nitrogen atoms in that ring. [1] It was the first antifungal approved for systemic use in people in the United States. [1] In veterinary medicine, it has been used for years to treat fungal infections in dogs, including: - Skin infections caused by yeast or fungi (the "ketoconazole for dogs skin" searches usually point here) - Ear infections with a fungal or yeast component - Some internal (systemic) fungal infections Your veterinarian may prescribe ketoconazole alone or alongside other treatments. For skin and ear problems, it is often part of a broader plan that includes medicated shampoos, ear cleaners, or other drugs. If your dog is also on antibiotics for a skin infection, it helps to know what to expect from those drugs. See [What Are the Side Effects of Antibiotics in Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/dog-antibiotics-side-effects). One practical point: ketoconazole is not the only antifungal your veterinarian can choose. It is an older option, and there are good reasons a newer drug may be a better fit for your dog. ## How Ketoconazole Works Ketoconazole blocks an enzyme that fungi need to build their cell membranes. Without a healthy membrane, the fungus cannot grow and multiply normally. This is why azoles are described as fungistatic, meaning they stop fungal growth instead of quickly killing the fungus outright. [1] That detail matters for treatment length. Because the drug holds the fungus in check while the body clears it, courses often run for weeks. Stopping early is a common reason infections come back. Ketoconazole also affects some hormone pathways in dogs, which is why it has occasionally been used for conditions beyond fungal infections. That use is uncommon today and is always a veterinarian's decision. ## Ketoconazole for Dogs Dosage: The Basics ### Who decides the dose Your veterinarian does. There is no safe universal dose you can apply at home. The right amount depends on your dog's weight, the infection being treated, how well your dog's liver is working, and what other medications your dog takes. If you are searching for a "ketoconazole for dogs dosage chart by weight," treat any chart you find as general information only. Your veterinarian has your dog's exam findings and blood work, and that is what should drive the prescription. ### Tablet strengths and the 200 mg question Ketoconazole comes as oral tablets. Dogs are sometimes prescribed a portion of a tablet, or a compounded liquid, depending on the calculated dose. Never split or crush a tablet unless your veterinarian or pharmacist tells you exactly how to do it. Some formulations are designed to release the drug in a specific way, and breaking them can change how much your dog absorbs. If your dog needs a very small dose, ask your veterinarian whether a compounding pharmacy can make a more precise form. ### How to give it Give ketoconazole with food unless your veterinarian says otherwise. Ketoconazole is a weakly basic drug, and it needs stomach acid to dissolve and absorb well. When stomach pH is higher (for example, in a dog taking antacids or acid reducers), oral absorption drops and blood levels fall. [2] Food also tends to reduce stomach upset. Practical tips: - Wrap the tablet in a small piece of food your dog will swallow whole, such as a bit of cheese or pill pocket. - Give it at the same times each day to keep drug levels steady. - Do not mix it into a full bowl of food unless your veterinarian approves, because you cannot tell how much your dog actually ate. - If your dog is on an acid reducer or antacid, tell your veterinarian before starting ketoconazole. [2] ### Missed doses If you miss a dose, give it as soon as you remember, unless it is almost time for the next one. In that case, skip the missed dose and go back to your regular schedule. Do not double up to make up for a missed pill. Call your veterinarian if you miss more than one dose in a row, since gaps can let the infection rebound. ## Ketoconazole for Dogs Side Effects Most dogs tolerate ketoconazole, but stomach upset is common, especially in the first few days. Giving the pill with a meal is the simplest way to reduce it. | Side effect | How common or serious | What to do | |---|---|---| | Vomiting | Common, usually mild | Give with food. Call your vet if vomiting repeats or your dog cannot keep water down | | Poor appetite | Common | Offer small, tempting meals. Call your vet if your dog skips more than a day of food | | Diarrhea | Common | Keep water available. Call your vet if it is bloody, black, or lasts more than a day | | Lethargy | Less common | Call your vet, especially if your dog seems weak or depressed | | Yellow gums, eyes, or skin | Uncommon but serious | Stop the drug and call your vet right away. This can signal liver trouble | | Itching, hives, facial swelling | Uncommon but serious | This may be an allergic reaction. Seek emergency care | | Bleeding or bruising easily | Rare but serious | Call your vet promptly for blood work | Because ketoconazole is processed by the liver, your veterinarian may want blood work before treatment and again during a long course. Liver enzyme changes are one of the main reasons this drug is monitored closely, and it is also a big reason newer antifungals are often chosen instead. [1] If your dog is on other medications for behavior, nausea, or seizures, ask about interactions before adding ketoconazole. Side effect profiles for those drugs are covered in [What Are the Side Effects of Gabapentin for Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/gabapentin-side-effects-dogs), [What Are the Side Effects of Cerenia for Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/cerenia-side-effects-dogs), and [What Are the Side Effects of Seizure Medication in Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/seizure-medication-side-effects-dogs). ## Who Should Not Take Ketoconazole and What Interacts With It Ketoconazole is not right for every dog. Your veterinarian may avoid it or choose a different antifungal if your dog: - Has liver disease or a history of abnormal liver values - Is pregnant, nursing, or being used for breeding - Is already taking drugs that stress the liver - Has had an allergic reaction to an azole antifungal - Is a very small dog or puppy, where precise dosing is harder Drug interactions are a major concern. Ketoconazole can change how the liver breaks down other medications, which can raise those drugs to unsafe levels or make them less effective. Common categories to mention to your veterinarian include: - Antacids, acid reducers, and proton pump inhibitors, which lower ketoconazole absorption [2] - Certain antibiotics - Steroids such as prednisone - Some seizure medications - Some heart medications - Certain pain relievers and anti-inflammatory drugs Bring a complete list to every visit, including supplements and over-the-counter products. Do not stop or start any medication on your own while your dog is on ketoconazole. ## Overdose and When to Call for Help If your dog eats more ketoconazole than prescribed, or gets into the bottle, call for help right away. Do not wait for symptoms. - Call your veterinarian or an emergency clinic immediately. - Call the ASPCA Animal Poison Control Center at (888) 426-4435. - Call the Pet Poison Helpline at (855) 764-7661. Signs of a significant overdose can include repeated vomiting, drooling, wobbliness, and lethargy. Take the bottle with you so the veterinarian knows the tablet strength and how many pills may be missing. ## Limitations and When to Contact a Veterinarian Ketoconazole is an older drug with real limitations. It absorbs poorly in small animals, has no injectable form, and tends to be less effective in dogs whose immune systems are suppressed. [1] Those shortcomings are exactly why triazole antifungals were developed. [1] For many dogs today, a newer antifungal is the better first choice. Call your veterinarian the same day if your dog: - Vomits more than once or cannot keep food or water down - Refuses food for more than 24 hours - Has diarrhea that is bloody or black - Seems unusually tired or weak - Develops yellow gums, eyes, or skin Go to an emergency clinic now if your dog: - Collapses or has a seizure - Has trouble breathing - Has facial swelling, hives, or widespread itching - May have eaten a large number of tablets Schedule a routine recheck if your dog is doing well but the infection is not clearly improving, if you are struggling to give the pills, or if a refill is needed. Long courses usually need monitoring, and your veterinarian may repeat blood work to check the liver. Every dog is different, and only your veterinarian can decide whether ketoconazole is safe and appropriate for yours. ## Frequently Asked Questions ### Can I give my dog ketoconazole without a prescription? No. Ketoconazole is a prescription antifungal, and the dose must be calculated for your dog's weight and health. Giving a human dose or a dose from an online chart can cause serious side effects. Talk to your veterinarian first. ### How long does it take for ketoconazole to work in dogs? Improvement in skin or ear infections often takes a few weeks, and internal fungal infections take longer. Because the drug slows fungal growth instead of killing it quickly, finishing the full course matters. Your veterinarian will set a recheck to judge progress. ### Can ketoconazole be used for dogs with yeast infections in the ears? Yes, it is sometimes used for yeast-related ear problems, often along with medicated ear cleaner or drops. Ear infections frequently have more than one cause, so an exam and sometimes a sample are needed. Do not put human antifungal creams in your dog's ears without veterinary guidance. ### Is ketoconazole safe to give with other medications? Not always. Ketoconazole can interact with antacids, acid reducers, steroids, seizure drugs, certain antibiotics, and other medications. Tell your veterinarian about everything your dog takes, including supplements. Your veterinarian may adjust doses or pick a different antifungal. ### What should I do if my dog vomits after taking ketoconazole? Try giving the next dose with a small meal, since food often reduces stomach upset. If vomiting repeats, if your dog cannot keep water down, or if you see blood, call your veterinarian. Do not give a second dose to replace a vomited pill unless your veterinarian tells you to. ## Related Articles - [What Are the Side Effects of Gabapentin for Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/gabapentin-side-effects-dogs) - [What Are the Side Effects of Antibiotics in Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/dog-antibiotics-side-effects) - [What Are the Side Effects of Cerenia for Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/cerenia-side-effects-dogs) - [What Are the Side Effects of Trazodone for Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/trazodone-side-effects-dogs) - [What Are the Side Effects of Seizure Medication in Dogs?](/knowledge/veterinary-medicine/pet-medication-guide/seizure-medication-side-effects-dogs) - [CBD Oil for Dogs: Dose Safety and Drug Interaction Warnings](/knowledge/veterinary-medicine/nutrition/cbd-oil-for-dogs-dose-safety-and-drug-interaction-warnings) - [Ketoconazole Shampoo for Dogs: Uses, Safety, and How to Bathe](/knowledge/veterinary-medicine/pet-medication-guide/ketoconazole-shampoo-for-dogs) - [Ketoconazole for Dog Ear Infections: Does It Help?](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/ketoconazole-dog-ear-infection) - [Terbinafine for Dogs: Side Effects, Dosage, and Safety](/knowledge/veterinary-medicine/pet-medication-guide/terbinafine-dogs-side-effects-dosage) ## References 1. [Azoles for Use in Animals - Pharmacology](https://www.merckvetmanual.com/pharmacology/antifungal-agents/azoles-for-use-in-animals). Merck Veterinary Manual. 2. [Cocrystal mitigates the effects of elevated gastric pH on oral absorption of weakly basic drugs: a case study with ketoconazole-succinic acid cocrystal on beagle dogs](https://pubmed.ncbi.nlm.nih.gov/42107844/). European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, 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: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)