Mirtazapine (Oral)

Mirtazapine is an oral tablet used to treat patients clinically diagnosed with depression, especially major depressive disorder (MDD).


Major depressive disorder is a mental health condition where a patient has extreme and persistently low, sad or gloomy moods. Mirtazapine effectively elevates a patient's mood by affecting certain chemicals in the brain.

There are potentially serious risks in taking this antidepressant. While providing a mental balance, the medicine may change the moods and mental health of patients in ways that are not expected.

Some patients, especially children, teenagers, and young adults, are at a higher risk for increased suicidal thoughts. Adults over 24 may also experience an increase in suicidal thoughts, particularly when their dose is decreased or increased.

The medicine is not usually used to treat children under the age of 18 but has been used in cases where it was the best treatment for the child's mental health.

Patients with mental illnesses such as bipolar disorder or manic depression are also more likely to have increased thoughts and behaviors relating to suicide.

The medicine may cause a serious condition known as serotonin syndrome in some patients. It also increases the risk of developing an infection.

Mirtazapine is the generic name for this antidepressant which is sold in the US as the brand names Remeron Soltab and Remeron. Patients are treated with it only if their doctor prescribed it.

Conditions Treated

Type Of Medicine

  • Tetracyclic Antidepressant

Side Effects

Serious side effects

Mirtazapine is known to cause some serious side effects and some of them may be life-threatening. Serious adverse effects include suicidal thoughts, serotonin syndrome, episodes of manic depression (bipolar disorder), weakened immune system, and eye problems.

One of the most serious and life-threatening adverse reactions to this drug are thoughts and acts of suicide.

Call your doctor immediately or seek emergency medical care right away if any of the following thoughts or suicide-related actions occur. There may be other suicidal actions or thoughts not listed here.

Thoughts and actions related to suicide:

  • Trying to commit suicide (end your life)
  • Thinking about dying or killing yourself
  • Trouble sleeping
  • Fresh episodes of depression
  • Depression that becomes worse
  • Fresh episode of panic attacks or anxiety
  • Unusual changes in mood or behavior
  • Anxiety or panic attacks that becomes worse
  • Impulsive or dangerous actions
  • Aggressive or violent actions or behaviors
  • Feeling restless, irritable, agitated or angry
  • Increased level of talking or activities that is not normal

Using this antidepressant may also cause a life-threatening condition known as serotonin syndrome. The following are some symptoms of this condition:

  • Confusion
  • Trouble thinking
  • Agitation
  • Seeing or hearing something that is not there (hallucinations)
  • Coma
  • High blood pressure (Hypertension)
  • Low blood pressure (Hypotension)
  • Twitching or stiffness of the muscles
  • Problems with your coordination
  • Racing heartbeat
  • Nausea or vomiting
  • Sweating or fever
  • Diarrhea

Mirtazapine may trigger episodes of manic depression in patients with bipolar disorder (manic-depressive disorder). Some symptoms are as follows. Call your doctor right away if you experience them.

Actions related to manic episodes:

  • Racing thoughts
  • Unusually grand ideas
  • Behaving recklessly
  • Extreme increase in energy
  • Trouble sleeping (severe)
  • Feeling extremely happy or irritable
  • Talking faster or more than usual

This medicine may decrease white blood cells which may lead to a weakening of your immune system. When this happens, it may be a lot easier for you to get an infection. Tell your doctor right away if you have the following symptoms of an infection:

  • Sores in the nose or mouth
  • Fever
  • Sore throat
  • Chills
  • Flu-like symptoms (for example, vomiting, fatigue or body aches)

Some patients develop problems with their eyes while using Mirtazapine. If this happens to you, call your doctor immediately. Symptoms include:

  • Vision changes
  • Eye pain
  • Redness or swelling in or around the eye

Also call your doctor right away if you notice any of the following general side effects, even though some of them rarely occur:

Less commonly

  • Swelling
  • Shortness of breath
  • Increased or decreased movement
  • Mental or mood changes (such as agitation, thinking in a way that is unusual, feelings of not caring, anxiety or confusion)
  • Skin rash

Rarely occur

  • Menstrual pain
  • Sore in the mouth
  • Menstrual cycle (periods) changes
  • Convulsions (seizures)
  • Decrease in sexual ability
  • Chills or fever
  • Sore throat
  • Mood or mental changes (such as mood swings, feeling unusually excited, feelings of being outside the body, anger or hallucinations seeing, feeling or hearing things that are not there)

The following are side effects that may occur, but they may not require medical attention. They can be managed at home and tend to disappear on their own during treatment.

However, if you experience any of them and it becomes worse or bothersome tell your doctor or healthcare professional.

More commonly occur

Less commonly occur

  • Nausea
  • Muscle pain
  • Pain in the stomach or abdomen
  • Excessive thirst
  • Abnormal dreams
  • Pain in the back
  • Vomiting
  • Low blood pressure (Hypotension)
  • Dizziness (especially when getting up suddenly from a sitting or lying position)
  • Fainting
  • Weakness
  • Frequent urge to urinate
  • Increased sensitivity to touch
  • Feeling as if you or your surroundings are constantly moving
  • Shaking or trembling

Some patients may experience other side effects not listed in this guide. Tell your doctor or healthcare professional if you experience any unusual symptom while using Mirtazapine.

Your doctor or healthcare professional may also give you advice on ways to reduce or prevent side effects.

You may report side effects by calling the US FDA at 1-800-FDA-1088.


Mirtazapine comes as an immediate-release tablet you take by mouth. It also comes as a tablet that disintegrates/dissolves in your mouth.

Dosage of Mirtazapine varies from patient to patient. Your doctor will decide your dose based on your condition, medical history, and presence of other medical problems if any.

Follow all directions given to you by your doctor, pharmacist and prescription label when taking this medicine. Read the patient information leaflet for additional instructions.

The prescription label should tell you how strong your dose is, the time between each dose, how often you should take it, and the duration of your treatment.

Preparing the oral disintegrating tablet for use:

  • Clean your hands by washing with soap and water and drying them.
  • Once you are ready to use the medicine, open the blister packet containing the tablet.
  • Open by gently peeling back the foil on the blister packet. Remove the tablet. You should not force the tablet through the back of the foil.
  • Once removed from the packet, place the tablet on top of your tongue right away without breaking or splitting it apart.
  • Allow the tablet to dissolves. This usually takes a few seconds.
  • Swallow the dissolved tablet with your saliva. It is not necessary to drink water or other liquids to swallow it.

The following is a general recommended dosage guide. You should stick to the dose prescribed for you by your doctor.

Treatment of depression using the oral disintegrating tablet:

Adults: Begin your treatment by taking 15 milligrams (mg) once a day, preferably at night and at bedtime. If needed, your doctor will adjust your dose but may not prescribe a dose of more than 45 mg per day.

Children: Treatment with Mirtazapine must be determined by your doctor.

It usually takes about 20 to 40 hours for the antidepressant to start working in the body. It may also take about 1 to 2 weeks for your body to adjust to the drug.

Missed dose

If you missed a dose of your medicine, take it as soon as possible. If it is close to the time of your next scheduled dose, skip the missed dose and take the upcoming dose on time. Continue taking your doses according to the schedule.


You may need urgent medical attention if you overdose on Mirtazapine. Call your doctor or 911 right away if this happens. You may also speak with the poison control center by calling 1-800-222-1222.


Your doctor may take precautions when treating you or give you special instructions regarding the use of food, alcohol, tobacco, and other medicines.

Food, alcohol, and tobacco

It is usually not recommended to use the following substance during treatment with this medicine. If it cannot be avoided, your doctor may change the dose or how often you use your medicine.

  • Tobacco

Certain side effects may worsen if the following substance is used during your treatment. If you cannot avoid using it, your doctor may change the dose or how often you use Mirtazapine.

  • Ethanol

Other medicines

Other medications may adversely interact with Mirtazapine and may affect the way it works.

The medicines on the following list have the potential to cause significant interactions with Mirtazapine. There may be other medications not listed here which may also cause adverse interaction.

Let your doctor know of all medications you are taking especially if you are already taking other antidepressants.

Using Mirtazapine with any of medicines on the following list is not recommended. Your doctor may still treat you with this antidepressant but may change one or more of the medicines you take. Your dose may also be adjusted.

  • Nialamide
  • Selegiline
  • Furazolidone
  • Isocarboxazid
  • Procarbazine
  • Linezolid
  • Rasagiline
  • Bromopride
  • Moclobemide
  • Safinamide
  • Methylene Blue
  • Tranylcypromine
  • Iproniazid
  • Phenelzine
  • Metoclopramide

Usually, it is not recommended to treat patients with Mirtazapine while they are taking any of the medicines on the following list.

If you must take any of these medicines to maintain your health, your doctor may still treat you with Mirtazapine but may change the dose or how often you use any of your medicines.

  • Quazepam
  • Tapentadol
  • Flunitrazepam
  • Nefazodone
  • Buspirone
  • Vilazodone
  • Dibenzepin
  • Warfarin
  • Hydroxytryptophan
  • Doxepin
  • Methadone
  • Duloxetine
  • Estazolam
  • Fentanyl
  • Amoxapine
  • Fluoxetine
  • Amitriptylinoxide
  • Diazepam
  • Flurazepam
  • Almotriptan
  • Fluvoxamine
  • Amitriptyline
  • Trimipramine
  • Granisetron
  • Levomilnacipran
  • Chlordiazepoxide
  • Eletriptan
  • Levothyroxine
  • Alprazolam
  • Escitalopram
  • Dextromethorphan
  • Lithium
  • Clonidine
  • Lofepramine
  • Amineptine
  • Desipramine
  • Melitracen
  • St John's Wort
  • Midazolam
  • Brompheniramine
  • Milnacipran
  • Dolasetron
  • Naratriptan
  • Buprenorphine
  • Nitrazepam
  • Clonazepam
  • Halazepam
  • Nortriptyline
  • Ondansetron
  • Ziprasidone
  • Opipramol
  • Bromazepam
  • Oxazepam
  • Clobazam
  • Oxycodone
  • Palonosetron
  • Cocaine
  • Ketazolam
  • Paroxetine
  • Vortioxetine
  • Chlorpheniramine
  • Pentazocine
  • Lorazepam
  • Temazepam
  • Prazepam
  • Carbamazepine
  • Protriptyline
  • Clomipramine
  • Frovatriptan
  • Sertraline
  • Zolmitriptan
  • Sibutramine
  • Lorcaserin
  • Cyclobenzaprine
  • Tianeptine
  • Meperidine
  • Tramadol
  • Propafenone
  • Tryptophan
  • Venlafaxine
  • Trazodone
  • Citalopram
  • Imipramine
  • Sumatriptan
  • Clorazepate
  • Desvenlafaxine
  • Rizatriptan
  • Triazolam

There is an increase in the risk of certain side effects if this antidepressant is used along with the following medicine. If using it during your treatment for depression is best for you, your doctor may change the dose or how often you use one or both of your medicines.

  • Cimetidine

Other medical problems

Other medical problems present in patients taking Mirtazapine may adversely interact with the medicine. It is important to tell your doctor of any other medical condition you have, especially the following

The following conditions (or history of) may become worse in patients taking this medicine. Use the antidepressant with caution:

  • Seizures
  • Mania or hypomania
  • High cholesterol levels in the blood (Hypercholesterolemia)
  • Bipolar disorder or manic depression
  • Low sodium levels in the blood (Hyponatremia)
  • Glaucoma (angle-closure type)

The following other condition may worsen due to taking this antidepressant:

Side effects may worsen in patients with the following conditions (or history of):

  • Heart disease
  • Stroke
  • Blood circulation problems
  • Low blood pressure (Hypotension)
  • Angina (severe chest pain)
  • Dehydration
  • Heart attack
  • Blood vessel disease
  • Low blood volume (Hypovolemia)

The medicine should be used with caution in patients who have the following conditions. Side effects may increase due to the slow removal of the medicine from their body.


  • Use Mirtazapine only if your doctor prescribed it to treat your depression. Your doctor should consider your medical history and the potential benefits and risks before treating you with this drug.
  • This medicine may cause depression to worsen in certain patients. Sudden and unusual changes in behavior or thoughts are signs of worsening depression.
  • Do not use this drug if you are allergic to it.
  • Tell your doctor if you are allergic to other medicines, foods, dyes, preservatives or animals.
  • Let your doctor know about all prescription or non-prescription medicines, herbal products or vitamins you take or plan to take.
  • Do not take Mirtazapine with monoamine oxidase inhibitors (MAOIs) such as phenelzine, tranylcypromine or isocarboxazid. They may increase the risk of the life-threatening condition called serotonin syndrome.
  • This medicine is not safe for use in children and is, therefore, not recommended.

A doctor may still determine use and dose for children under 18 years of age but must consider the potential risks of using it in this group of patients.

  • Tell your doctor if you are pregnant, may be pregnant or are breastfeeding. There may be a risk of harm to an unborn baby or breastfeeding infant if Mirtazapine is used by the pregnant or breastfeeding mother.
  • Elderly patients should be treated with caution due to the risk of confusion or kidney problems.
  • Mirtazapine may cause some serious side effects. Take the medicine exactly as prescribed. Do not take less or more of it than was prescribed. Do not use it more often than directed or for a longer time you were told to.
  • Using Mirtazapine may cause life-threatening side effects such suicidal thoughts or acts and serotonin syndrome. Patients with other mental illnesses such as bipolar disorder or manic depression (or history of) are at a higher risk of suicidal thoughts and actions.
  • At risk patients should pay close attention to sudden or unusual changes in feelings, thoughts or behavior, especially at the beginning of treatment. Call your doctor right away if you experience any of these symptoms.
  • The risk of suicidal thoughts or behaviors are also higher when the medicine dose is changed (increased or decreased).
  • The risk of suicidal tendencies may also occur in patients taking this drug but who do not have other mental illnesses.
  • Avoid the use of tobacco and alcohol during your treatment. Alcohol is especially known for increasing side effects such as dizziness and drowsiness.
  • Do not drive, operate machinery or do activities which require you to be alert unless you know how the medicine affects you.
  • Do not stop using the medication suddenly. If you do, you may experience withdrawal effects such as nausea, headache, dizziness or mood changes.
  • Do not miss your dose of this medication. Missing several doses (in a row) may also cause withdrawal symptoms. Talk to your doctor if you have these symptoms.
  • If your doctor decides to stop treating you, this should be done gradually to avoid withdrawal symptoms.
  • Let your household or family members know of the symptoms of serious side effects, especially suicidal thoughts and behavior. Tell them what they should do, such as seeking emergency medical help right away, if you display these signs.
  • Do not use Mirtazapine as a recreation drug just to get 'a œhigh'. You may experience serious side effects associated with using this drug, which may become fatal if used with other medicines, street drugs or alcohol.
  • Keep all appointments to follow up with your doctor. You will need to be checked often and monitored closely for side effects, especially suicidal thoughts or tendencies.


Store Mirtazapine at room temperature, away from direct light, heat, and moisture. Prevent it from freezing.

Keep it away from children and pets.

Throw away medicine when it has expired or is no longer needed.

Follow instructions for safe disposal given to you by your doctor, healthcare professional or your waste disposal agency.


Since its approval by the US Food and Drug Administration (FDA) in 1996, Mirtazapine has been used as a safe and effective drug for treating major depressive disorder (MDD).

However, due to the high risk of life-threatening adverse effects this medicine poses, the FDA requires that Mirtazapine be prescribed with "black-box" warnings to doctors, patients, and healthcare professionals. These warnings relate to the risk of suicide.

The most serious effect of using the medicine is the increased risk of suicidal thoughts and behaviors that threaten the life of a patient. Children, teenagers, and young adults are more likely to be affected in this way.

Patients are especially at risk when they first begin treatment and when their dose is increased or decreased. This requires both doctor and patient to closely monitor side effects and sudden or unusual changes in behavior, feelings, thoughts, and moods.

Major depressive disorder (MDD) itself poses a risk of suicidal thoughts and behaviors even when the patient is not taking antidepressants.

This medicine is known to worsen depression and increase side effects in patients with bipolar disorder or manic depression. It is also known for causing a life-threatening condition called serotonin syndrome and increasing the risk of developing an infection.

Patients are encouraged to let family members and caregivers know what serious side effects to look for and when to seek medical attention on their behalf.

Last Reviewed:
March 26, 2018
Last Updated:
April 16, 2018
Content Source: