Mirtazapine for Cats: The Go-To Appetite Stimulant
Works in 1-2 hours
Mirtazapine is the most commonly prescribed appetite stimulant for cats with anti-nausea effects. Standard dose is 1.88mg every 48-72 hours, or use Mirataz transdermal gel daily.
When a sick cat stops eating, mirtazapine is often the first medication vets reach for. Originally an antidepressant, it's now widely used in cats for its powerful appetite-stimulating effects. Here's everything you need to know.
Worried about your cat's appetite? VetLens can help you track eating patterns, medication doses, and weight changes over time.
Try VetLens FreeWhat Is Mirtazapine?
Mirtazapine is a medication that affects serotonin and other neurotransmitters. While it's an antidepressant in humans, in cats its most valuable effect is stimulating appetite. It also has anti-nausea properties.
Key Facts:
- • Drug class: Tetracyclic antidepressant
- • Primary use in cats: Appetite stimulation
- • Secondary benefits: Anti-nausea, anti-anxiety
- • Forms: Tablets (oral), Mirataz (transdermal gel)
- • Onset: 1-2 hours (oral), 1-2 days (transdermal)
Common Uses
- • Chronic Kidney Disease: Combats uremic nausea; helps maintain weight
- • Cancer: Counters appetite suppression from disease/chemo
- • Post-Illness Recovery: Jumpstarts eating after illness, surgery, hospitalization
- • Hepatic Lipidosis Prevention: Prevents fatty liver by encouraging eating
- • IBD / Pancreatitis: Reduces nausea; stimulates appetite
| Condition | Why Mirtazapine Helps |
|---|---|
| Chronic Kidney Disease | Combats uremic nausea; helps maintain weight |
| Cancer | Counters appetite suppression from disease/chemo |
| Post-Illness Recovery | Jumpstarts eating after illness, surgery, hospitalization |
| Hepatic Lipidosis Prevention | Prevents fatty liver by encouraging eating |
| IBD / Pancreatitis | Reduces nausea; stimulates appetite |
Oral vs. Transdermal: Which Is Better?
Oral Mirtazapine (Tablets): 1.88mg every 48-72 hours, works in 1-2 hours, $10-30/month. Faster and cheaper but requires pilling.
Mirataz (Transdermal Gel): 1.5-inch ribbon on ear daily, takes 1-2 days for full effect, $80-150/month. No pilling and FDA-approved but more expensive.
| Feature | Oral Mirtazapine | Mirataz (Transdermal) |
|---|---|---|
| Dose | 1.88mg per cat | 1.5-inch ribbon on ear |
| Frequency | Every 48-72 hours | Once daily |
| Onset | 1-2 hours | 1-2 days for full effect |
| Cost | $10-30/month | $80-150/month |
| Pros | Faster onset, cheaper | No pilling, FDA-approved |
| Cons | Requires pilling | More expensive, slower onset |
Which Should You Choose?
- • Can't pill your cat? Mirataz is easier
- • Need fast results? Oral works within hours
- • Budget concerns? Oral is much cheaper
- • Long-term use? Either works; owner preference matters
Dosing Details
Important:
Cats metabolize mirtazapine slowly. Unlike humans who take it daily, cats need it only every 48-72 hours to avoid accumulation. Cats with kidney or liver disease metabolize even slower.
Oral Mirtazapine:
- • Standard dose: 1.88mg per cat (1/8 of a 15mg tablet)
- • Frequency: Every 48 hours (healthy cats) to every 72 hours (CKD cats)
- • Administration: Can be given with or without food
- • Compounding: Available as flavored liquid or transdermal from compounding pharmacies
Mirataz Application:
- Wear disposable gloves
- Apply 1.5-inch ribbon to inner ear flap (pinna)
- Alternate ears each day
- Don't rub it in - let it absorb
- Avoid petting the ear area for 2 hours
Managing appetite loss in your cat?
Track food intake, medication doses, and weight changes. Know what's working and share progress with your vet.
Try VetLens FreeSide Effects
Common (Usually Mild)
Most cats tolerate mirtazapine well. Common side effects are usually temporary:
- • Increased vocalization - Meowing, "talking" more than usual
- • Affectionate behavior - Rubbing, purring, seeking attention
- • Restlessness/agitation - Pacing, inability to settle
- • Mild sedation - Some cats get sleepy instead
- • Ear irritation (Mirataz) - Redness at application site
Less Common
- • Vomiting or diarrhea
- • Tremors
- • Increased heart rate
- • Excessive drooling
Serotonin Syndrome (Rare but Serious)
If mirtazapine is combined with other serotonergic drugs (tramadol, fluoxetine, trazodone), there's a risk of serotonin syndrome: severe agitation, tremors, high heart rate, high temperature. Contact your vet immediately if these occur.
Special Considerations
- • Kidney Disease: Extend interval to every 72 hours; kidneys eliminate drug more slowly
- • Liver Disease: Use caution; liver metabolizes the drug
- • Hyperthyroidism: May be more sensitive; monitor heart rate
- • Multi-Cat Households: Prevent other cats from grooming treated ear (Mirataz)
| Condition | Consideration |
|---|---|
| Kidney Disease | Extend interval to every 72 hours; kidneys eliminate drug more slowly |
| Liver Disease | Use caution; liver metabolizes the drug |
| Hyperthyroidism | May be more sensitive; monitor heart rate |
| Multi-Cat Households | Prevent other cats from grooming treated ear (Mirataz) |
Mirtazapine vs. Other Appetite Stimulants
- • Mirtazapine: Serotonin effects, every 48-72h, most commonly used and also anti-nausea
- • Cyproheptadine: Antihistamine, 1-2x daily, less reliable older option
- • Entyce (capromorelin): Ghrelin agonist, daily, off-label for cats and newer
| Medication | How It Works | Frequency | Notes |
|---|---|---|---|
| Mirtazapine | Serotonin effects | Every 48-72h | Most commonly used; also anti-nausea |
| Cyproheptadine | Antihistamine | 1-2x daily | Less reliable; older option |
| Entyce (capromorelin) | Ghrelin agonist | Daily | Off-label for cats; newer |
Cost Comparison
- • Oral mirtazapine: $10-30/month
- • Compounded transdermal: $30-60/month
- • Mirataz (brand): $80-150/month
| Form | Monthly Cost |
|---|---|
| Oral mirtazapine | $10-30 |
| Compounded transdermal | $30-60 |
| Mirataz (brand) | $80-150 |
Related Reading
Track Your Cat's Appetite Recovery
VetLens helps you:
- Log food intake and appetite changes
- Track medication doses and timing
- Monitor weight trends over time
- Share progress reports with your vet
Frequently Asked Questions
How quickly does mirtazapine work in cats?
Oral mirtazapine typically stimulates appetite within 1-2 hours. Transdermal Mirataz may take 1-2 days to show full effect. Most cats will eat more within the first few doses if the medication is going to work for them.
What is the difference between mirtazapine pills and Mirataz?
Oral mirtazapine is given every 48-72 hours due to slow metabolism in cats. Mirataz (transdermal gel) is applied to the ear flap daily and is FDA-approved specifically for cats. Mirataz is easier to give but more expensive ($80-150/month vs $10-30 for pills).
What are the side effects of mirtazapine in cats?
Common side effects include vocalization (meowing more), restlessness, affectionate behavior, and mild sedation. Less common: vomiting, tremors, or agitation. Serotonin syndrome is rare but possible if combined with other serotonergic drugs like tramadol.
Is mirtazapine safe for cats with kidney disease?
Yes, mirtazapine is commonly used in CKD cats to stimulate appetite. However, cats with kidney disease metabolize mirtazapine more slowly, so dosing is typically every 48-72 hours (not daily) to prevent accumulation and toxicity.
How long can my cat be on mirtazapine?
Mirtazapine can be used long-term if needed. Many CKD and cancer cats take it for months to years. Your vet may periodically reassess whether it's still necessary.
What if my cat still won't eat?
If mirtazapine doesn't help, your vet may investigate underlying causes, try anti-nausea medications like Cerenia, or consider a feeding tube for severe cases.
Can I combine mirtazapine with anti-nausea medication?
Yes, mirtazapine is often combined with Cerenia (maropitant) or ondansetron for maximum effect in cats with significant nausea.