Remeron (mirtazapine): uses, side effects, and what to expect

If you and your psychiatrist are considering Remeron, you probably have questions about how it works, what it treats, and what to expect. Remeron (mirtazapine) is an atypical antidepressant primarily used for major depressive disorder, and it stands out for its ability to also help with sleep and appetite. Here is what you should know before your next conversation with your psychiatrist.

Key takeaways

• Remeron (mirtazapine) is an atypical antidepressant approved to treat major depressive disorder.
• It works by boosting norepinephrine and serotonin through a different mechanism than most other antidepressants.¹
• Sleep and appetite improvements may happen within the first week or two, but full mood benefits typically take two to six weeks.¹
• Weight gain and drowsiness are among the most commonly reported side effects.²

What is Remeron?

Remeron is the brand name for mirtazapine, an atypical antidepressant. Unlike SSRIs or SNRIs, mirtazapine works through a different set of receptors in the brain to increase levels of norepinephrine and serotonin.¹ It is most commonly prescribed for major depressive disorder, and psychiatrists sometimes choose it when sleep difficulties or low appetite are part of the picture.

What does Remeron treat?

Remeron is FDA-approved and prescribed for major depressive disorder (MDD). It is often a good fit when depressive symptoms include insomnia and loss of appetite.

Off-label uses

Psychiatrists sometimes prescribe mirtazapine off-label, meaning for conditions beyond its FDA-approved use. If your psychiatrist recommends it for one of these purposes, they can walk you through why it may be a good fit for your symptoms.

• Anxiety, including generalized anxiety disorder and panic disorder
• PTSD

You can learn more about mirtazapine for anxiety on the Talkiatry blog.

How does Remeron work?

Most antidepressants work by slowing the reabsorption of mood-related brain chemicals so more of them stay active. Mirtazapine takes a different approach: Instead of blocking reabsorption, it blocks certain receptors that normally act as brakes on norepinephrine and serotonin release.¹ This allows more of both chemicals to flow, which can help improve mood, sleep, and appetite over time.

• Boosts norepinephrine and serotonin. Mirtazapine works differently from other antidepressants by blocking certain receptors that normally limit these neurotransmitters.¹
• Improves sleep and appetite. Because of its specific receptor activity, mirtazapine can also help with sleep difficulties and low appetite.¹
• Supports mood over time. By increasing key brain chemicals involved in mood regulation, mirtazapine can reduce symptoms of depression.¹

3 things a Talkiatry psychiatrist wants you to know about Remeron

• It can help with sleep and appetite. Mirtazapine often improves sleep and increases appetite, especially at lower doses. If either of these is a struggle for you, that is worth bringing up with your psychiatrist.
• It tends to cause weight gain. Increased appetite means some people experience weight gain, which is worth discussing with your psychiatrist so you can plan for it together.
• It takes time to work for mood. Sleep and appetite changes can show up early, but mood improvements build gradually. If you do not feel a difference after a few weeks, bring that up with your psychiatrist rather than stopping on your own. Adjustments are a normal part of finding the right fit.

Common side effects of Remeron

Like all medications, Remeron can cause side effects. The most commonly reported ones include:¹

• Drowsiness
• Dizziness
• Increased appetite
• Weight gain

Talk to your psychiatrist if any of these feel persistent, severe, or get in the way of your day.

Serious side effects of Remeron and when to seek help

Serious side effects are less common, but it is important to recognize them. Contact your psychiatrist or seek emergency care if you notice any of the following:¹

• Signs of infection, such as fever, chills, sore throat, mouth sores, or flu-like symptoms
• Symptoms of serotonin syndrome, including fever, sweating, confusion, fast or irregular heartbeat, muscle stiffness or twitching, agitation, hallucinations, loss of coordination, nausea, vomiting, or diarrhea
• Chest pain or fast heartbeat
• Signs of angle-closure glaucoma, such as eye pain, changes in vision (including colored rings around lights), or swelling or redness in or around the eye
• Unusual bleeding or bruising
• A severe allergic reaction, including rash, itching, hives, blisters, hoarseness, swollen glands, difficulty breathing or swallowing, or swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs
• Seizures
• Headache, unsteadiness, or problems with thinking, concentration, or memory
• New or worsening depression, thoughts of harming or killing yourself, extreme worry, agitation, panic attacks, difficulty sleeping, aggressive behavior, irritability, acting without thinking, severe restlessness, or frenzied abnormal excitement, especially in children, teenagers, and young adults under 24

Call your psychiatrist right away or seek emergency care if you experience any of these symptoms.

What to watch for when starting Remeron

Starting a new medication comes with an adjustment period. Here are some things to keep in mind:¹

• It may take several weeks or longer to feel the full benefit for your mood, even if sleep and appetite improve sooner.
• Mirtazapine may cause drowsiness. Do not drive or operate machinery until you know how it affects you.
• Alcohol can worsen side effects. Discuss safe alcohol use with your psychiatrist.
• Take Remeron once a day at bedtime.
• Continue taking it even if you feel well. Do not stop without talking to your psychiatrist first.

What to do if you miss a dose of Remeron

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue your regular schedule. Do not take a double dose to make up for a missed one.

Who should talk to a psychiatrist before taking Remeron

Some health conditions, medications, and life situations change how Remeron is prescribed. Tell your psychiatrist if any of the following apply to you:¹

• You are allergic to mirtazapine or any of its ingredients
• You have taken or stopped taking an MAO inhibitor within the past two weeks
• You have a personal or family history of long QT syndrome
• You have or have had a heart attack, low blood pressure, or high cholesterol or triglycerides
• You have or have had heart, kidney, or liver disease
• You have a history of heavy alcohol use, substance use, or misuse of prescription medications
• You are pregnant, planning to become pregnant, or breastfeeding
• You have phenylketonuria (PKU), as the orally disintegrating tablets contain aspartame that produces phenylalanine