Key points
- Major depressive disorder in adults is the one FDA-approved use.
- Sleepiness, increased appetite, weight gain and dizziness are the most common side effects on the label.
- A rare but serious warning involves very low white blood cells, so fever, sore throat or mouth sores should be reported.
- RemeronSolTab dissolves on the tongue and contains phenylalanine, which matters for people with phenylketonuria (PKU).
- The label advises lowering the dose gradually rather than stopping suddenly whenever possible.
What mirtazapine is
Mirtazapine is an antidepressant that is not an SSRI or an SNRI. The brand names are Remeron, a film-coated tablet, and RemeronSolTab, an orally disintegrating tablet. Generic versions are also sold.
The disintegrating tablet has a few handling rules on its label. It is removed from the blister and placed on the tongue right away, where it breaks down in saliva to be swallowed. It should not be chewed, crushed or split, and it cannot be stored once it is out of the blister.
What it is approved for
The Food and Drug Administration (FDA) label lists one use: major depressive disorder in adults. It is not approved for children and teens.
MedlinePlus says it is sometimes prescribed for other uses and to ask a doctor or pharmacist. If someone suggests mirtazapine for another reason, ask them whether that use is approved.
How it is thought to work
The label says the way mirtazapine works in depression is unclear. Its effect could come from blocking certain receptors, called alpha-2 receptors, that normally act as brakes on nerve signaling, which may increase the activity of norepinephrine and serotonin. That is a different route from blocking reuptake, which is how SSRIs and SNRIs are described.
What taking mirtazapine can be like
Sleepiness is the most common side effect on the label. It says it is unclear whether people develop tolerance to the sleepiness, and it cautions against driving or using machinery until you are reasonably sure how the medicine affects you. MedlinePlus says alcohol can make side effects worse, so ask your prescriber about it.
Appetite and weight can also change. The label reports increased appetite and weight gain as common effects, along with raised cholesterol and triglycerides in some people. If either change bothers you, or you already manage weight or cholesterol concerns, say so early.
MedlinePlus says it may take several weeks or longer to feel the full benefit. The National Institute of Mental Health (NIMH) notes that it may take several tries to find the medicine with the fewest side effects.
Do not stop mirtazapine suddenly or without talking to your prescriber. The label lists dizziness, abnormal dreams, tingling or electric shock sensations and other symptoms after stopping, especially stopping abruptly, and says to lower the dose gradually whenever possible.
Side effects and warnings
Boxed warning: antidepressants increased the risk of suicidal thoughts and behaviors in children, teens and young adults in short-term studies. Everyone taking an antidepressant should be watched closely for worsening and for new suicidal thoughts. MedlinePlus says the risk may be more likely in the first few months and when a dose goes up. If you are in crisis, call or text 988 or call 911. Locascio Wellness does not provide emergency services, and our crisis resources page lists other options.
Dangerous combinations: the label says mirtazapine must not be taken with monoamine oxidase inhibitors (MAOIs), including linezolid and intravenous methylene blue, or within 14 days of stopping one, because of serotonin syndrome. People allergic to mirtazapine or its ingredients should not take it. Other medicines raise serotonin syndrome risk too, including triptans, tramadol and St. John's wort.
- Very low white blood cells (agranulocytosis): rare in studies. Report sore throat, fever, mouth sores or other signs of infection right away.
- Heart rhythm: QT prolongation and related dangerous rhythms have been reported, mostly with overdose or in people with other risk factors, so tell your prescriber about heart problems and other medicines.
- Severe skin and whole-body reactions: rash, fever and swollen glands can be signs of a reaction called DRESS, and need medical care right away.
- Phenylketonuria: RemeronSolTab contains phenylalanine, so people with PKU should tell their prescriber.
- Also on the label: dizziness on standing, liver enzyme increases, low sodium, seizures, angle-closure glaucoma, and mania in people with bipolar disorder.
Can mirtazapine be managed online in Pennsylvania and New York
The FDA label gives mirtazapine no controlled-substance schedule and describes no certified setting or restricted program. Blood tests, such as cholesterol checks or a white blood cell count if infection signs appear, cannot happen over video, so ask how they would be arranged, for example through a local lab or your primary care office.
A licensed psychiatrist on our team, a Doctor of Osteopathic Medicine (DO), treats depression online by secure video, for people physically located in Pennsylvania or New York during each visit. Whether it is an option for you is a decision for you and your prescriber. Ask us whether our psychiatrist can help. You can also compare options in our overview of medications for depression.
Our therapists do not prescribe. They see clients in Pennsylvania, West Virginia, Arizona, Colorado and Florida, not New York, so a New York reader can get psychiatry here but not therapy here. Ask us about fees and coverage.
Common questions
Does mirtazapine make you sleepy?
It can. The label lists sleepiness as its most common side effect, and it says it is unclear whether people develop tolerance to it. The label advises caution with driving or using machinery until you are reasonably sure how the medicine affects you. Report sleepiness that interferes with daily life to your prescriber rather than changing anything yourself.
Does mirtazapine cause weight gain?
Increased appetite and weight gain are among its most common side effects on the label, and some people also see higher cholesterol and triglycerides. Not everyone has these effects. If weight or cholesterol matters for your health, tell your prescriber from the beginning, so you can plan together how to keep track of any change.
Should I tell my prescriber if I am pregnant or breastfeeding?
Yes. Tell your prescriber if you are pregnant, planning a pregnancy or breastfeeding, and do not stop mirtazapine on your own because of it. Your prescriber can go over what the label says about your situation. Share every medicine and supplement you take too, since some can interact with mirtazapine.
Sources
Published by Locascio Wellness. Published November 5, 2026. Clinically reviewed by Kenneth M. Levy, DO, Psychiatrist (Pennsylvania license OS007464L). This page is general information, not medical advice or a diagnosis.