Mirtazapine (Remeron)

What mirtazapine is

Mirtazapine is a medication sold under the brand name Remeron. It works on serotonin and norepinephrine, two of the chemical messengers nerve cells use to communicate, but it does so through a different route than most similar medicines, and it has a noticeably calming, or sedating, effect. Because of that, it is often chosen when poor sleep or low appetite are part of what someone is dealing with.

What it treats

Your clinician might suggest mirtazapine for one of these, among other possible off-label uses:

• Depression, and it is often chosen when poor sleep or low appetite are part of the picture

Whether it is a good fit depends on several factors, including your history and what you are working on. As with everything in psychiatry, that is decided case by case.

How it works

Honestly, no one knows with complete certainty how mirtazapine produces its benefit. What research supports is that it increases the activity of two of the chemical messengers nerve cells use, norepinephrine and serotonin, though it does this differently from many other medicines. It also blocks histamine, the same signal involved in drowsiness and appetite, which is part of why it tends to be calming and can make you hungrier. The biology is only part of the picture: how much a medication helps, and how it feels, is individual. Two people on the same medication can have very different experiences.

How to take it

There is no single right way to take mirtazapine; it depends on you and your clinician. It comes as a regular tablet and as a tablet that dissolves on the tongue, and it is usually taken once a day at bedtime, with or without food, because it tends to make people sleepy. The plan you and your clinician make together is the one to follow, not a number you read online. A few general points apply broadly:

• Take it the way you and your clinician agreed, usually at bedtime so the drowsiness works in your favor.
• Because it can make you drowsy, be careful with driving or anything that needs full alertness until you know how it affects you. Alcohol and other sedating medicines can add to that.
• If you miss a dose, ask your clinician or pharmacist what to do rather than doubling up.
• Try not to stop on your own. Your clinician can lower it gradually if and when that makes sense.

What to expect

This varies from person to person. Some effects can show up before the benefit does: the drowsiness and a bump in appetite, if they happen, often appear early, while any lift in mood usually takes longer, commonly a few weeks and sometimes more. For some people the calming effect on sleep is welcome from the start. That early stretch is common and tends to settle. If nothing has shifted after a fair trial, that is useful information, not a dead end, and there are other options. As always, this is case by case.

Side effects

Not everyone gets side effects, and many that do happen ease over the first weeks. The lists below are possibilities, not certainties.

Possible more common side effects:

• Feeling drowsy or sleepy, especially at first
• Increased appetite and weight gain
• Dizziness
• Dry mouth
• Constipation

If any of these stick around or bother you, they are worth raising. Send a non-urgent message through the patient portal or bring it up at your next visit; often a small change helps.

Less common, but concerning side effects that could require emergency care:

• Signs of an infection your body is struggling to fight: fever, chills, sore throat, mouth sores, or feeling suddenly unwell. Mirtazapine can rarely lower the white blood cells that fight infection, so these signs are worth taking seriously
• Signs of an allergic reaction: rash, hives, blisters, or swelling of the face, lips, tongue, or throat, or trouble breathing or swallowing
• Serotonin syndrome: agitation, confusion, a racing heart, fever, heavy sweating, or stiff or twitching muscles, sometimes after another medication is added
• A seizure
• Unusual bleeding or bruising
• Chest pain or a fast heartbeat
• Feeling abnormally high, wired, or irritable, with racing thoughts and far less need for sleep than usual
• Any new or worsening thoughts of harming yourself

For any of these, use the help options at the top of this page: call 911 or go to the nearest emergency department for a medical emergency or severe reaction, or call or text 988 for a mental health crisis.

When to reach out, and where

For routine questions, side effects that can wait, or how things are going, send your clinician a message through the patient portal. These are part of your ongoing care and are answered in the normal course of a few business days, so they are best for things that are not urgent.

If something feels urgent, you do not need to wait for a reply. The help options at the top of this page are the fastest way to get care: 911 or the nearest emergency department for a medical emergency or severe reaction, or 988 any time for a mental health crisis or thoughts of self-harm.

Questions to ask your clinician

• What are you hoping mirtazapine will help with in my case?
• How and when will we know if it is working?
• What should I do if I notice side effects?
• How long should I give it before we reassess?
• What is the plan if this one turns out not to be the right fit?
• How will we handle stopping it, if and when we get there?