Mirtazapine for Anxiety: Benefits and Side Effects


For many people, anxiety can feel all-consuming, making long-term relief a long and frustrating process. However, medications like mirtazapine may offer the support you need to manage these challenging symptoms. 

Although primarily prescribed as an antidepressant, mirtazapine has shown benefits for those coping with anxiety who are experiencing trouble sleeping or consistent bad moods.

In this article, we’ll explore how mirtazapine works, its potential benefits and side effects, and what to consider before starting treatment.

What is Mirtazapine? 

Mirtazapine — often referred to by its brand name Remeron — is an FDA-approved medication used to treat major depressive disorder (MDD). 

It belongs to a class of medications called tetracyclic antidepressants, and is sometimes prescribed off-label for other conditions, such as: 

  • Generalized anxiety disorder (GAD) 

  • Panic disorder

  • Post-traumatic stress disorder (PTSD)

  • Social anxiety disorder

  • Obsessive-compulsive disorder (OCD) 

How does mirtazapine work for anxiety? 

Mirtazapine is primarily prescribed for depressive disorders, but it’s also used to treat anxiety disorders by acting on two key neurotransmitters — serotonin and norepinephrine.

These chemicals play an important role in managing mood and stress. Serotonin and norepinephrine may help a person balance emotions and feel more relaxed.

When serotonin and norepinephrine levels are low, feelings of nervousness, restlessness, or worry may become more intense. 

Mirtazapine works by blocking specific receptors in the brain that limit the release of serotonin and norepinephrine. By blocking these receptors, mirtazapine allows these neurotransmitters to stay active in the brain for longer. 

The effects of the medication are also helpful for dealing with insomnia or feelings of sadness.

Does Mirtazapine Cause Any Side Effects?

It’s possible to experience side effects when starting any medication. Most side effects of mirtazapine are mild and improve as the body adjusts to the medication.

Common side effects

Although it’s a medication that is generally well-tolerated, some side effects may include: 

Severe side effects

Adverse side effects from mirtazapine are rare, but it’s important to be aware that they may occur in some cases. These could include: 

  • Low white blood cell count: Low white blood cell levels can increase the risk of infection and flu-like symptoms, such as a sore throat, fever, and chills. 

  • Liver issues: There have been reported cases of drug-induced liver issues, leading to a yellow color in the eyes and skin (jaundice), which resolved after stopping mirtazapine. 

  • Low sodium levels: This side effect is more common in older adults. Low sodium levels may lead to confusion or altered mental states. 

Speak to your doctor if you notice any side effects that don’t go away or improve.  A healthcare provider may assess your symptoms and adjust your treatment or dosage if needed.

Key Point: Can Mirtazapine Cause Weight Gain?

Some studies suggest mirtazapine may lead to weight gain. Mirtazapine may increase appetite and slow down metabolism.

This occurs because the medication blocks certain serotonin receptors, which may make people feel hungrier.

Mirtazapine is sometimes prescribed off-label to help people who struggle with poor appetite and unintentional weight loss. The medication is sometimes prescribed to people with chronic illnesses who are experiencing symptoms.

How Long Does Mirtazapine Take to Work? 

Everyone responds to mirtazapine differently, some may notice improvements sooner, while others might take longer to feel significant relief.

Mirtazapine may work faster compared to selective serotonin reuptake inhibitors (SSRIs). The medication typically begins to take effect within one to two weeks of starting the medication. 

Some people may notice early improvements in their sleeping patterns during this time — which is a good sign that the medication is beginning to work. 

It may take about four to six weeks to feel the full benefits of mirtazapine, especially for chronic mood changes or intense anxiety symptoms. 

It’s important to keep taking the medication as prescribed, even if you don’t feel better right away. Regular check-ins with your healthcare provider are essential for monitoring your progress and making any necessary adjustments to your treatment plan.

What is the Proper Dosage of Mirtazapine?

Remeron (mirtazapine) can be consumed as an immediate-release tablet or as an orally disintegrating tablet known as Remeron SolTab. 

The usual starting dose ranges from 15 to 30 mg (milligrams) per day, depending on your specific needs and medical history. 

If you notice that your anxiety symptoms are not improving, your healthcare provider may increase your dosage to a maximum of 45 mg per day. 

How to take mirtazapine for anxiety

Most people are advised to take mirtazapine once per day. It’s recommended to take the medication in the evening because it may cause drowsiness. 

In some cases, your doctor may suggest dividing the daily dose into two parts, with a larger dose taken in the evening, and a smaller dose in the morning. 

Mirtazapine can be taken with or without food, and it doesn’t need to be taken the same way each time. Food doesn’t significantly impact the medication’s absorption. 

If you’re prescribed the immediate-release tablet, swallow it whole with water. For the orally disintegrating tablet, allow it to dissolve on your tongue without water. 

What to do if you miss a dose 

If you remember a missed dose within one to four hours of your usual dosing time, take the tablet right away. 

However, if it’s almost time for your next dose, skip the missed dose and resume your regular dosing schedule. 

You should never take two doses at once to make up for a missed dose, as this may lead to excessive drowsiness or excessive concentrations of the medication in your system. 

Avoiding an overdose 

Always take mirtazapine exactly as prescribed by your doctor, and never exceed the recommended dose. 

The medication works best when it’s consistently taken at the right dose over time. Be sure to always consult your healthcare provider before increasing your dosage. Increasing the dose on your own won’t make mirtazapine work faster. 

Although the risk of a fatal mirtazapine overdose is rare, taking more than the prescribed amount may lead to serious side effects, such as: 

  • A rapid or irregular heart rate

  • Extreme drowsiness

  • Confusion 

Be sure to seek emergency help right away if you believe you have consumed too much of the medication.

What Medications Does Mirtazapine Interact With?

Mirtazapine may interact with other medications, which may affect how effective it is. Taking mirtazapine with other medications can also increase the risk of adverse side effects. Here are a few key interactions to be aware of: 

Monoamine oxidase inhibitors (MAOIs)

These are a type of medication used in the treatment of depression, anxiety disorders, and sometimes Parkinson’s disease. 

Using mirtazapine with MAOIs may result in dangerously high levels of serotonin in the bloodstream, potentially leading to a serious condition called serotonin syndrome

It’s advised to wait at least 14 days after stopping an MAOI before starting mirtazapine.

A note on SSRIs and SNRIs

The risk of developing serotonin syndrome is lower when mirtazapine is combined with SSRIs or serotonin and norepinephrine reuptake inhibitors (SNRIs).

Pay close attention to any symptoms that arise and consult your healthcare provider immediately if you have concerns.

Central nervous system (CNS) depressants 

Alcohol and benzodiazepines — such as Xanax or Klonopin — can enhance the sedative effects of mirtazapine. This may lead to impaired coordination, slower reflexes, or extreme drowsiness. 

Be careful not to drive or operate heavy machinery while taking these medications.  

Blood thinners

Mirtazapine may interact with blood thinning medication like Warfarin. When using blood thinner medication with mirtazapine, it may be more difficult for your blood to clot or increase the risk of clots forming. 

To ensure your blood is clotting properly, your healthcare may order regular blood tests and adjust your dosage if needed.

Antiepileptic drugs

Medications like carbamazepine and phenytoin — commonly used to control seizures — may affect how your body processes mirtazapine. 

These drugs may speed up the breakdown of mirtazapine in your body, making it less effective at managing depression and anxiety symptoms.

If you use antiepileptic medication, your healthcare provider might need to adjust your dosage of mirtazapine to ensure it works as intended.

What Happens if You Stop Taking Mirzapatine?

It’s not advised to stop taking mirtazapine without speaking to your healthcare provider first. 

Stopping the medication abruptly may lead to withdrawal symptoms — also known as antidepressant discontinuation syndrome. These symptoms may include: 

  • Insomnia

  • Dizziness

  • Mood changes

  • Tingling sensations 

  • Muscle aches

Your healthcare provider will be able to create a treatment plan to gradually reduce your mirtazapine dose. This gives your body time to adjust and lower the risk of developing severe symptoms. 

Where Can I Learn More About Mirtazapine and Other Anxiety Medications?

Discover how mirtazapine and other anxiety medications support mental health and may improve your well-being with LifeMD.

Expert healthcare providers can guide you through personalized treatment options for managing anxiety and other mental health conditions.

Schedule your appointment today to speak with a licensed healthcare provider about your health.

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This article is intended for informational purposes only and should not be considered medical advice. Consult a healthcare professional or call a doctor in the case of a medical emergency.

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