Medication Guide
Remeron (Mirtazapine): Uses, Side Effects & What to Expect
Mirtazapine — sold as Remeron — is an atypical antidepressant for depression. It works differently from SSRIs and is often chosen when poor sleep and low appetite are part of the picture, because it tends to be sedating and to increase appetite. It also has fewer sexual side effects than SSRIs and is usually taken at night.
Clinically reviewed by the Lyte Psychiatry Clinical Team · Last reviewed June 2026
What is mirtazapine?
Mirtazapine is an atypical antidepressant — specifically a noradrenergic and specific serotonergic antidepressant (NaSSA). It raises norepinephrine and serotonin through a different mechanism than SSRIs, and its antihistamine effect makes it calming and appetite-stimulating. It’s sold as Remeron and as a generic.
What does Remeron treat?
Mirtazapine is FDA-approved for major depressive disorder in adults. It’s frequently chosen when depression comes with insomnia and weight/appetite loss, since its side-effect profile can actually help with those.
How long does it take to work?
Better sleep and appetite often appear within the first week or two, while the fuller mood benefit usually builds over four to six weeks. It’s usually taken at bedtime.
Common side effects
The most common side effects come from its calming, appetite-raising nature:
- Drowsiness (especially at first)
- Increased appetite and weight gain
- Dry mouth
- Constipation
- Dizziness
Interestingly, low doses can be more sedating than higher ones. It tends to cause fewer sexual side effects than SSRIs.
A note on dosing
Dosing is individualized by your prescriber and usually taken at night. This page intentionally doesn’t give a specific number — the goal is the lowest effective dose, adjusted with your clinician.
An important safety note
Like all antidepressants, mirtazapine carries an FDA “boxed warning”: in people under 25, antidepressants can in rare cases increase suicidal thoughts, especially early in treatment. If you or someone you love has thoughts of self-harm, call or text 988 (the Suicide & Crisis Lifeline) right away.
Good to know
Because mirtazapine can be quite sedating, use care with driving until you know how it affects you, and avoid combining it with alcohol or other sedatives. It’s not addictive, but it should be tapered with your prescriber rather than stopped abruptly.
Frequently asked questions
What is Remeron (mirtazapine) used for?
Mirtazapine (brand name Remeron) is an atypical antidepressant FDA-approved for major depressive disorder. It is often chosen when depression comes with poor sleep and low appetite.
How long does mirtazapine take to work?
Improvements in sleep and appetite often appear within the first 1 to 2 weeks, while the full benefit for mood usually takes 4 to 6 weeks.
Does mirtazapine cause weight gain?
Yes, mirtazapine commonly increases appetite and can cause weight gain because of its antihistamine effect. For some people with low appetite that is actually helpful; discuss your priorities with your prescriber.
Why is mirtazapine taken at night?
Mirtazapine is sedating, so taking it at bedtime uses that effect to help with sleep and reduces daytime drowsiness.
Is mirtazapine addictive?
No. Mirtazapine is not a controlled substance and is not addictive. It should still be tapered with your prescriber rather than stopped suddenly.
Does mirtazapine cause sexual side effects?
Mirtazapine tends to cause fewer sexual side effects than SSRIs, which is sometimes a reason it is chosen. Individual responses vary.
Related pages
This page is for general education and is not medical advice or a substitute for care from your own clinician. Medication decisions should always be made with a licensed prescriber who knows your history.
Wondering if Remeron is right for you?
Our Texas psychiatry team can review your symptoms, history, and goals and build a plan that fits — with close follow-up. Same-week appointments available.
Book an appointment