Mirtazapine vs Entyce for Cats: Which Appetite Stimulant?

Name: Mirtazapine vs Entyce for Cats: Which Appetite Stimulant?
Creator: Dr. Zubair Khalid

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

Mirtazapine and Entyce are both appetite stimulants for cats, but they work in completely different ways. Mirtazapine is an antidepressant that also blocks nausea and comes as a transdermal ear gel or oral tablet, while Entyce (capromorelin) is an oral liquid that mimics the hunger hormone ghrelin. The right choice, or whether to combine them, depends on your cat's diagnosis, other medications, and how easy each form is for you to give.

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

Quick Answer

Mirtazapine is available as a transdermal ointment applied to the inner ear (Mirataz) and as oral tablets, while Entyce is an oral liquid given by mouth.
Mirtazapine was first developed as a human antidepressant, and in cats it both stimulates appetite and reduces nausea, so it can help cats who feel sick as well as cats who simply will not eat [1].
Entyce and mirtazapine can be used together in some cats, but only your veterinarian should decide that, because both drugs affect appetite through different pathways and combining them changes the risk profile.
Side effects differ: mirtazapine commonly causes vocalization, restlessness, and ear redness with the transdermal form, while Entyce's side effects are usually milder and involve drooling, vomiting, or head shaking.
Never adjust the dose or stop either drug on your own. Call your veterinarian if your cat stops eating again, vomits repeatedly, or acts sedated or agitated.

What Are Mirtazapine and Entyce, and What Do Veterinarians Use Them For?

Mirtazapine is a drug that was initially developed to control nausea and has been shown to be an effective appetite stimulant in cats [1]. Veterinarians have used it for years in cats with chronic kidney disease, cancer, and other conditions that cause weight loss and poor appetite. The FDA approved a transdermal formulation called Mirataz, which is applied to the skin and produces blood levels that are safe and effective at increasing appetite [1].

Entyce is the brand name for capromorelin, an oral liquid appetite stimulant approved for cats. It belongs to a different drug family than mirtazapine and works by mimicking ghrelin, the hormone your cat's body releases when the stomach is empty. Your veterinarian may reach for Entyce when a cat needs a short-term appetite boost, or when mirtazapine has not worked well or caused side effects.

Both drugs are used for the same basic problem: a cat that will not eat. That problem is serious. Cats who stop eating for even a few days can develop hepatic lipidosis, a dangerous liver condition. Appetite stimulants buy time and support recovery, but they do not fix the underlying disease.

How Do These Appetite Stimulants Work in Cats?

Mirtazapine

Mirtazapine works on several brain chemicals at once. It blocks certain serotonin receptors, which reduces nausea, and it increases norepinephrine and serotonin activity in the appetite centers of the brain. That combination is why it can help a nauseated cat and a depressed, uninterested cat at the same time.

The transdermal form is absorbed through the skin of the ear. Studies have shown that applying it this way produces blood levels that are safe and effective at increasing appetite [1]. This matters for a practical reason. Giving a pill to a cat that will not eat is hard, and the transdermal route avoids that fight.

Mirtazapine also has anti-nausea benefits beyond appetite. In cats receiving doxorubicin chemotherapy, oral mirtazapine significantly increased body weight compared with placebo, and appetite and activity scores were significantly higher during mirtazapine treatment [2]. In cats with lymphoma receiving chemotherapy, transdermal mirtazapine was applied daily for 14 days, and body weight, body condition score, and muscle condition score improved in 60%, 30%, and 10% of cats respectively [3].

Entyce (Capromorelin)

Capromorelin is a ghrelin receptor agonist. Ghrelin is often called the hunger hormone. It rises before meals and signals the brain to increase food intake. Capromorelin mimics that signal, so the cat's brain receives a hunger message even when the stomach is empty.

Because capromorelin acts on a different receptor system than mirtazapine, the two drugs do not compete with each other. That is the scientific basis for combining them, which some veterinarians do when one drug alone is not enough.

Dosing Basics for Mirtazapine vs Entyce for Cats

Your veterinarian calculates the dose from your cat's weight and health. Do not use a dose from the internet, a friend's cat, or an old prescription bottle.

Who decides the dose

Only your veterinarian. Mirtazapine dosing depends on the form (transdermal versus oral), the cat's weight, kidney and liver function, and other medications. Entyce dosing depends on weight and is given as a liquid. One published study used transdermal mirtazapine at 2 mg per cat daily for 14 days in cats with lymphoma [3], and another used oral mirtazapine at 1.88 mg per cat every 48 hours in cats on doxorubicin chemotherapy [2]. These are study protocols, not dosing instructions for your cat. Your veterinarian will choose what fits your situation.

For a general walkthrough of how these doses are calculated, see Mirtazapine Appetite Stimulant: Dose for Cats and Dogs Guide.

How each one is given

Mirtazapine transdermal ointment is applied to the inner surface of the ear [3]. Owners in one survey found application to the ear easy in 97% of cases, and 91% followed the manufacturer's instructions to alternate ears [4]. Alternating ears matters because it reduces skin irritation and keeps absorption consistent.

Oral mirtazapine tablets are given by mouth. They are bitter, which is one reason the transdermal form became popular. A newer orally disintegrating tablet with taste masking and controlled release is being developed to address the bitterness and absorption problems of conventional oral forms [5].

Entyce is a liquid given by mouth, usually with a dosing syringe. It is typically given once daily, about an hour before a meal, so the hunger signal arrives when food is available.

Missed dose

If you miss a dose, give it when you remember unless it is almost time for the next one. Then skip the missed dose and continue on schedule. Never double up. If you are unsure, call your veterinarian or your pharmacist.

Side Effects of Mirtazapine and Entyce in Cats

Side effect	How common or serious	What to do
Increased vocalization, restlessness, redness of the ear	Reported by 20% of owners using transdermal mirtazapine, most often these three signs [4]	Note the timing. If it is mild and your cat is eating, mention it at the next visit. If your cat is distressed, call your vet
Mirtazapine-related adverse events during chemotherapy	Occurred in 4 of 20 cats (20%) and did not require stopping the drug [3]	Report any new signs to your vet so they can decide whether to continue
Drooling, vomiting, head shaking, lip smacking with Entyce	Usually mild and short-lived	Give with or shortly before food as directed. Call your vet if vomiting repeats
Sedation, stumbling, severe agitation, tremors	Uncommon but serious	Call your veterinarian the same day or go to an emergency clinic
Not eating after 24 to 48 hours on the drug	Serious, because cats can develop liver problems quickly	Call your veterinarian the same day

Mirtazapine can also cause serotonin-related signs if combined with other serotonin drugs. Tell your veterinarian about every medication, supplement, and topical product your cat receives.

Who Should Not Take Mirtazapine or Entyce, and What Interacts With Them?

Cats with known hypersensitivity to either drug should not receive it. Cats with certain liver or kidney conditions may need dose adjustments or a different drug. Your veterinarian will review your cat's bloodwork before prescribing.

Drug interactions matter for both. Mirtazapine interacts with other serotonin-active drugs, including some antidepressants, tramadol, and certain anti-nausea drugs. It can also interact with medications that affect liver enzymes. If your cat takes insulin or another diabetes medication, ask your veterinarian about timing and monitoring. For background on how these interactions are managed, see Drug Interactions with Antidiabetic Medications in Dogs and Cats.

Entyce has fewer known interactions, but it still should be reviewed against your cat's full medication list. Do not start any new drug, supplement, or topical product without telling your veterinarian.

If your cat takes gabapentin for pain or anxiety, mention it. Sedation from gabapentin can be confused with mirtazapine side effects, and the combination can make a cat unusually quiet. See Gabapentin For Cats for more on what to expect.

Can You Combine Entyce and Mirtazapine for Cats?

Yes, in some cases. Because mirtazapine and capromorelin act on different receptors, a veterinarian may prescribe both when one alone is not enough. This is a decision your veterinarian makes after weighing your cat's diagnosis, kidney and liver values, and other drugs.

Do not combine them on your own. Giving two appetite stimulants without veterinary supervision can mask a worsening underlying disease, and it makes side effects harder to interpret. If your cat is already on one and still not eating, call your veterinarian instead of adding the other.

Overdose and When to Call a Veterinarian or Poison Control

If your cat ate a human mirtazapine tablet or received too much of either medication, treat it as an emergency. Signs of mirtazapine overdose in cats can include severe agitation, vocalization, tremors, rapid heart rate, vomiting, and disorientation. Entyce overdose can cause vomiting, drooling, and lethargy.

Call your veterinarian or an emergency clinic right away. You can also contact poison control. The ASPCA Animal Poison Control Center is available at (888) 426-4435, and the Pet Poison Helpline is available at (855) 764-7661. Have the medication bottle, the strength, and your best estimate of how much your cat consumed.

If your cat ate a human antidepressant, including mirtazapine, read My Cat Ate My Antidepressant: Is It an Emergency? while you are on the way to the vet.

Limitations and When to Contact a Veterinarian

Appetite stimulants do not treat the cause of your cat's poor appetite. They support nutrition while your veterinarian diagnoses and treats the underlying problem. Individual cases need a veterinarian who can examine your cat, review bloodwork, and adjust the plan.

Call your veterinarian the same day if:

Your cat has not eaten in 24 hours, or has eaten very little for 48 hours.
Your cat vomits more than once or twice, or vomits after every dose.
Your cat seems sedated, wobbly, or unusually agitated.
You see new drooling, head shaking, or ear redness that was not there before.
You miss more than one dose in a row.

Go to an emergency clinic now if:

Your cat is having tremors, seizures, or severe agitation.
Your cat is struggling to breathe.
Your cat collapsed or cannot stand.
You know or suspect an overdose.

Schedule a routine visit if your cat is eating but you have concerns about long-term use, cost, or whether the drug is still needed. About half of owners in one survey used transdermal mirtazapine for less than 14 days [4], which suggests many cats need it only short term. Your veterinarian can reassess whether to continue, taper, or switch.

Frequently Asked Questions

Is Entyce or Mirataz better for a cat that will not eat?

Neither is universally better. Mirataz (transdermal mirtazapine) also reduces nausea, which helps cats who feel sick, and it avoids pill fights. Entyce works through the hunger hormone pathway and is a liquid given by mouth. Your veterinarian will pick based on your cat's diagnosis, bloodwork, and how easily you can give each form.

Can I use Entyce and mirtazapine together for my cat?

Only if your veterinarian prescribes both. The two drugs act on different receptors, so combining them is sometimes done when one alone is not enough. Never add a second appetite stimulant on your own, because it can hide a worsening illness and make side effects hard to sort out.

How fast do these appetite stimulants work in cats?

Many cats respond within the first day or two, but timing varies by drug, dose, and illness. In one study of dogs, mirtazapine increased food acceptance on the first day, with feeding starting about 120 minutes after administration [6]. Cats are not dogs, so do not expect identical timing. If your cat has not eaten within 24 hours of starting treatment, call your veterinarian.

What are the most common side effects of transdermal mirtazapine in cats?

Increased vocalization, redness of the ear, and restlessness are the most frequently reported signs. In one survey, 20% of owners reported side effects, most often those three [4]. Application was considered easy by 97% of owners, and 91% alternated ears as instructed [4]. Most side effects are mild, but call your vet if your cat seems distressed.

Is mirtazapine safe for cats with kidney disease?

Mirtazapine is commonly prescribed for cats with chronic kidney disease, which was the most common reason for prescription in one survey of owners [4]. Safety still depends on your cat's kidney values, other medications, and overall condition. Your veterinarian will decide the dose and monitor your cat, so do not use a dose from any other source.

References

FDA Approves Appetite Stimulant for Cats. Cornell University College of Veterinary Medicine.
Oral mirtazapine decreases the gastrointestinal adverse effects in cats on doxorubicin chemotherapy. Veterinary journal (London, England : 1997), 2024.
Appetite Stimulant and Anti-Emetic Effect of Mirtazapine Transdermal Ointment in Cats Affected by Lymphoma Following Chemotherapy Administration: A Multi-Centre Retrospective Study. Animals : an open access journal from MDPI, 2022.
Owner's Perspective About the Use of Mirtazapine Transdermal Ointment in Cats-A Survey-Based Study. Animals : an open access journal from MDPI, 2025.
Overcoming mirtazapine's therapeutic limitations in veterinary practice: Development of a taste - masked orally disintegrating tablet with microsphere-based controlled release. Veterinary journal (London, England : 1997), 2026.
Evaluation of the Short-Term Effects of Mirtazapine on Appetite Stimulants in Dogs: A Retrospective Study and a Placebo-Controlled Trial. Animals : an open access journal from MDPI, 2025.