Mirtazapine (Remeron): Uses, Dosage, Side Effects, and What to Expect
Mirtazapine (brand name Remeron) is an antidepressant FDA-approved for depression that’s taken once a day at bedtime. It stands out for two effects most antidepressants don’t have: it’s strongly sedating and it boosts appetite. That makes it a good fit when depression comes with insomnia, poor appetite, or weight loss, and a poor fit when weight gain is a concern. It causes fewer sexual side effects than SSRIs and usually starts at 15 mg, with a maximum of 45 mg.
Noradrenergic and specific serotonergic antidepressant
15–45 mg at bedtime
Better sleep and appetite
No. Can be prescribed by telehealth
What Is Mirtazapine Used For?
- Major depressive disorder in adults. This is its FDA-approved use (depression treatment).
- Depression with insomnia, poor appetite, or weight loss, where its side effects become benefits
- Adding to an SSRI or SNRI when depression has only partly responded
- Off-label for anxiety, sleep, and nausea, in selected cases
How Does Mirtazapine Work?
Mirtazapine works differently from SSRIs. Instead of blocking serotonin reuptake, it blocks alpha-2 receptors, which increases the release of both norepinephrine and serotonin. It also blocks certain serotonin receptors (5-HT2 and 5-HT3) linked to anxiety, insomnia, nausea, and sexual side effects. Finally, it strongly blocks histamine receptors, which causes drowsiness and increased appetite.
Mirtazapine Dosage
| Step | Dose | Notes |
|---|---|---|
| Starting | 15 mg at bedtime | Some prescribers start lower in older adults |
| Adjusting | Increases at least 1–2 weeks apart | Based on response and side effects |
| Maximum | 45 mg/day | FDA-labeled ceiling |
- Take it at bedtime. Drowsiness is strongest in the first hours after a dose.
- Orally disintegrating tablets (SolTab) dissolve on the tongue, which helps if swallowing pills is hard.
- Its half-life is about 20 to 40 hours, so morning grogginess is common at first and usually improves.
- Many clinicians observe that lower doses can feel more sedating than higher ones, because the antihistamine effect dominates at low doses. Your prescriber may use this when choosing a dose.
How Long Does Mirtazapine Take to Work?
Sleep and appetite often improve within the first several days. Mood typically improves over 2 to 6 weeks, with full effect in 8 weeks or more. If sleep improves but mood doesn’t after 4 to 6 weeks, that’s a reason to revisit the plan with your prescriber.
Mirtazapine Side Effects
| Side effect | Mirtazapine | Placebo |
|---|---|---|
| Drowsiness | 54% | 18% |
| Increased appetite | 17% | 2% |
| Weight gain | 12% | 2% |
| Dizziness | 7% | 3% |
Source: Mirtazapine FDA prescribing information, 6-week U.S. trials.
Dry mouth and constipation are also common. In trials, 7.5% of people gained 7% or more of their body weight, versus none on placebo, and cholesterol and triglycerides rose in some people.
What it tends not to cause
Compared with SSRIs, mirtazapine causes less nausea, fewer sexual side effects, and less early jitteriness. For some people that trade is worth the drowsiness and weight gain.
Serious but rare risks
- Low white blood cell count (agranulocytosis). Rare: 2 of 2,796 people in premarketing trials. Call your prescriber about a sore throat, fever, mouth sores, or signs of infection.
- Serotonin syndrome with other serotonergic drugs
- Low sodium, mostly in older adults
- Heart rhythm changes, mainly in overdose or with other risk factors
- Mania in people with undiagnosed bipolar disorder
Who Should Be Careful With Mirtazapine
- Do not combine with an MAOI or within 14 days of one
- Weight, diabetes, or cholesterol concerns
- Older adults, who clear it more slowly and face more fall risk from sedation
- Liver or kidney disease, heart conditions, or bipolar disorder
- Jobs or driving that need full alertness, until you know how it affects you
Alcohol and sedatives: avoid alcohol, and use caution with benzodiazepines or other sedating medicines, which add to drowsiness.
Stopping: taper with your prescriber. Stopping abruptly can cause rebound insomnia, nausea, anxiety, and dizziness.
Mirtazapine vs. Trazodone and SSRIs
| Mirtazapine | Trazodone | SSRIs | |
|---|---|---|---|
| Sedation | Strong | Strong at low doses | Varies; can cause insomnia |
| Appetite and weight | Increases | Usually neutral | Small gain over time |
| Sexual side effects | Less common | Less common (rare priapism) | Common |
| Typical role | Depression with poor sleep or appetite | Mostly low-dose for sleep | First-line for depression and anxiety |
See our guides to trazodone for sleep and sertraline (Zoloft).
How We Approach Mirtazapine at Samz Mental Health
- Use it where its side effects help, such as depression with insomnia, low appetite, or weight loss
- Talk through weight and metabolic risk before starting, and track weight over time
- Screen for safety, including other sedating medicines, alcohol use, and bipolar history
- Adjust through follow-up with ongoing medication management
Can You Get Mirtazapine Prescribed Online?
Yes. Mirtazapine isn’t a controlled substance, so a licensed prescriber can prescribe it after a telehealth evaluation when appropriate. Samz Mental Health offers video visits for adults physically located in Texas, New York, Florida, Colorado, Washington, Maryland, New Hampshire, New Mexico, and Iowa.
In-network with Aetna, Cigna, UnitedHealthcare, Optum, and Carelon Behavioral Health. See insurance details. Need to be seen soon? We offer same-day psychiatrist appointments.
Frequently Asked Questions About Mirtazapine
What is mirtazapine used for?
It’s FDA-approved for depression and is especially useful when depression comes with insomnia or poor appetite.
What is the usual mirtazapine dose?
Usually 15 mg at bedtime to start, up to a maximum of 45 mg.
Does mirtazapine cause weight gain?
Often, yes. Increased appetite and weight gain are among its most common side effects.
Is mirtazapine good for sleep?
It’s very sedating, which helps when depression comes with insomnia. Using it only for sleep is off-label.
How long does mirtazapine take to work?
Sleep and appetite within days; mood over 2 to 6 weeks.
Does mirtazapine cause sexual side effects?
Less often than SSRIs and SNRIs.
Can I drink alcohol on mirtazapine?
No. It adds to sedation and can worsen depression.
Can I get mirtazapine prescribed online?
Yes, after a telehealth evaluation. Samz Mental Health sees patients by video in nine states.
Talk to a Provider About Mirtazapine
Book a video evaluation with a board-certified psychiatric nurse practitioner. Same-day appointments available. No referral needed.
References
- Mirtazapine tablets prescribing information. Drugs.com professional label; also on DailyMed.
Medical disclaimer: This page is for education and is not a substitute for a personal medical evaluation. Don’t start, stop, or change any medication without talking to your prescriber. If you’re in crisis or thinking about harming yourself, call or text 988 (Suicide & Crisis Lifeline) or call 911.