Remeron Side Effects

Generic name: mirtazapine

Medically reviewed by Drugs.com. Last updated on Apr 21, 2025.

Note: This document provides detailed information about Remeron Side Effects associated with mirtazapine. Some dosage forms listed on this page may not apply specifically to the brand name Remeron.

Applies to mirtazapine: oral tablet, oral tablet disintegrating.

Precautions

It is very important that your doctor check your progress at regular visits, to allow changes in your dose and help reduce any side effects. Blood tests may be needed to check for unwanted effects.

Do not take mirtazapine (the active ingredient contained in Remeron) with a monoamine oxidase (MAO) inhibitor (eg, isocarboxazid [Marplan®], linezolid [Zyvox®], methylene blue injection, phenelzine [Nardil®], selegiline [Eldepryl®], tranylcypromine [Parnate®]). Do not start taking mirtazapine during the 2 weeks after you stop a MAO inhibitor and wait 2 weeks after stopping mirtazapine before you start taking a MAO inhibitor. If you take them together or do not wait 2 weeks, you may develop confusion, agitation, restlessness, stomach or intestinal symptoms, a sudden high body temperature, an extremely high blood pressure, or severe seizures.

Mirtazapine may cause a serious condition called serotonin syndrome if taken together with some medicines. Do not use mirtazapine with buspirone (Buspar®), fentanyl (Abstral®, Duragesic®), lithium (Eskalith®, Lithobid®), tryptophan, St. John's wort, or some pain or migraine medicines (eg, rizatriptan, sumatriptan, tramadol, Frova®, Imitrex®, Maxalt®, Relpax®, Ultram®, Zomig®). Check with your doctor first before taking any other medicines with mirtazapine. Check with your doctor right away if you are having agitation, difficulty in breathing, a fast heartbeat, hallucinations, a high fever, high or low blood pressure, increased sweating, loss of bladder control, seizures, severe muscle stiffness, unusually pale skin, or tiredness while you are taking this medicine.

Mirtazapine may cause some teenagers and young adults to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. Some people may have trouble sleeping, get upset easily, have a big increase in energy, or start to act reckless. If you or your caregiver notice any of these unwanted effects, tell your doctor right away. Let the doctor know if you or anyone in your family has bipolar disorder (manic-depressive) or has tried to commit suicide.

This medicine may add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for allergies or colds, sedatives, tranquilizers, or sleeping medicines, prescription pain medicine or narcotics, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are taking this medicine.

This medicine can temporarily lower the number of white blood cells in your blood, increasing your chance of getting an infection. If you can, avoid people with infections. Check with your doctor right away if you think you are getting an infection or if you have a fever or chills, sore throat, sores in the mouth, lower back or side pain, or painful or difficult urination.

Do not suddenly Stop taking mirtazapine without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are using before stopping completely. This may help prevent a possible worsening of your condition and reduce the possibility of withdrawal symptoms such as headache, nausea, or a general feeling of discomfort or illness.

This medicine may increase your weight. Your doctor may need to check your weight on a regular basis while you are using this medicine.

Mirtazapine may cause drowsiness, trouble with thinking, or trouble with controlling body movements. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that requires you to be alert, well-coordinated, and able to think well.

This medicine may cause serious skin reaction, including drug reaction with eosinophilia and systemic symptoms (DRESS). Check with your doctor right away if you have black, tarry stools, chest pain, chills, cough, fever, painful or difficult urination, sore throat, sores, ulcers, or white spots on the lips or in the mouth. swollen glands, unusual bleeding or bruising, or unusual tiredness or weakness.

Hyponatremia (low sodium in the blood) may occur with this medicine. This is more common in elderly patients, those who are taking diuretic medicines for high blood pressure, or those who have decreased amounts of fluid in the body due to severe diarrhea or vomiting. Check with your doctor right away if you have confusion, difficulty concentrating, headaches, memory problems, weakness, and unsteadiness.

Dizziness, lightheadedness, or fainting may occur, especially when you get up suddenly from a lying or sitting position. Getting up slowly may help. If this problem continues or gets worse, check with your doctor.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Common side effects of Remeron

Some side effects of mirtazapine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Serious side effects of Remeron

Along with its needed effects, mirtazapine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking mirtazapine:

For healthcare professionals

Applies to mirtazapine: oral tablet, oral tablet disintegrating.

Nervous system adverse events

• Very common (10% or more): Somnolence (up to 54%)
• Common (1% to 10%): Dizziness, tremor, headache, sedation/drowsiness
• Uncommon (0.1% to 1%): Hypesthesia, hypokinesia, vertigo, amnesia, hyperkinesia, paresthesia, lethargy
• Rare (0.01% to 0.1%): Syncope, migraine, ataxia, dyskinesia, extrapyramidal syndrome, coordination abnormal, dysarthria, dystonia, reflexes increased, restless legs, akathisia (psychomotor restlessness)
• Very rare (less than 0.01%): Vascular headache, cerebral ischemia, aphasia, nystagmus, stupor, dementia, paralysis, grand mal convulsion, hypotonia, taste loss, myoclonus, parosmia
• Frequency not reported: Hypertonia, taste perversion, convulsions (insults)
• Postmarketing reports: Impaired concentration, cerebrovascular disorder, movement disorders^[Ref]

Gastrointestinal

• Very common (10% or more): Dry mouth (up to 25%), constipation (up to 13%)
• Common (1% to 10%): Nausea
• Uncommon (0.1% to 1%): Abdominal pain, abdominal syndrome acute, vomiting, diarrhea
• Rare (0.01% to 0.1%): Abdomen enlarged, eructation, glossitis, nausea and vomiting, gum hemorrhage, stomatitis, colitis, oral hypoesthesia
• Very rare (less than 0.01%): Tongue discoloration, ulcerative stomatitis, salivary gland enlargement, increased salivation, intestinal obstruction, pancreatitis, aphthous stomatitis, gastritis, gastroenteritis, oral moniliasis, tongue edema
• Frequency not reported: Dyspepsia, flatulence, oral paresthesia, mouth edema^[Ref]

Metabolic

• Very common (10% or more): Increased appetite (up to 17%), weight gain (up to 12%)
• Uncommon (0.1% to 1%): Anorexia
• Rare (0.01% to 0.1%): Dehydration, weight loss
• Very rare (less than 0.01%): Gout, acid phosphatase increased, diabetes mellitus, hyponatremia
• Frequency not reported: Hypertriglyceridemia
• Postmarketing reports: Hypercholesterolemia, hyperlipidemia^[Ref]

Psychiatric

• Common (1% to 10%): Abnormal dreams, thinking abnormal, confusion
• Uncommon (0.1% to 1%): Apathy, depression, agitation, anxiety, insomnia
• Rare (0.01% to 0.1%): Delirium, delusions, depersonalization, increased libido, hallucinations, manic reaction/mania, neurosis, hostility, emotional lability, euphoria, paranoid reaction, nightmares/vivid dreams
• Very rare (less than 0.01%): Drug dependence, psychotic depression, withdrawal syndrome, serotonin syndrome, aggression
• Frequency not reported: Nervousness, decreased libido, suicidal ideation, suicidal behavior, somnambulism
• Postmarketing reports: Psychomotor restlessness, drug withdrawal symptoms, paroniria^[Ref]

Cardiovascular

• Common (1% to 10%): Peripheral edema, edema
• Uncommon (0.1% to 1%): Hypertension, vasodilation, orthostatic hypotension
• Rare (0.01% to 0.1%): Angina pectoris, myocardial infarction, bradycardia, ventricular extrasystoles, hypotension
• Very rare (less than 0.01%): Chest pain substernal, atrial arrhythmia, bigeminy, cardiomegaly, phlebitis, left heart failure
• Frequency not reported: Chest pain, palpitation, tachycardia, postural hypotension, ECG changes
• Postmarketing reports: Ventricular arrhythmia, Torsades de pointes, generalized edema, localized edema^[Ref]

There was a mean increase in heart rate observed in patients given this drug compared to placebo (3.4 bpm versus 0.8 bpm, respectively); however, the clinical significance of this difference is unknown.^[Ref]

Musculoskeletal

• Common (1% to 10%): Back pain, myalgia
• Uncommon (0.1% to 1%): Myasthenia, arthralgia, twitching
• Rare (0.01% to 0.1%): Neck rigidity, neck pain, arthritis, tenosynovitis
• Very rare (less than 0.01%): Pathologic fracture, osteoporosis fracture, bone pain, myositis, tendon rupture, arthrosis, bursitis
• Postmarketing reports: Increased creatine kinase blood levels, rhabdomyolysis^[Ref]

Respiratory

• Common (1% to 10%): Dyspnea
• Uncommon (0.1% to 1%): Cough increased, sinusitis
• Rare (0.01% to 0.1%): Epistaxis, bronchitis, asthma, pneumonia
• Very rare (less than 0.01%): Respiratory/pulmonary embolus, asphyxia, laryngitis, pneumothorax, hiccup
• Frequency not reported: Pharyngitis, rhinitis
• Postmarketing reports: Pulmonary embolism^[Ref]

Genitourinary

• Common (1% to 10%): Urinary frequency
• Uncommon (0.1% to 1%): Urinary tract infection
• Rare (0.01% to 0.1%): Dysuria, urinary incontinence, urinary retention, vaginitis, hematuria, breast pain, amenorrhea, dysmenorrhea, leukorrhea, impotence
• Very rare (less than 0.01%): Polyuria, urethritis, metrorrhagia, abnormal ejaculation, breast engorgement, breast enlargement, urinary urgency, menorrhagia^[Ref]

Other

• Common (1% to 10%): Asthenia
• Uncommon (0.1% to 1%): Malaise, thirst, fatigue
• Rare (0.01% to 0.1%): Chills, fever, face edema, ulcer, ear pain, deafness, hyperacusis
• Very rare (less than 0.01%): Healing abnormal, partial transitory deafness, otitis media
• Frequency not reported: Pain, tinnitus^[Ref]

Immunologic

• Common (1% to 10%): Influenza/flu syndrome
• Frequency not reported: Infection^[Ref]

Dermatologic

• Uncommon (0.1% to 1%): Pruritus, rash, exanthema
• Rare (0.01% to 0.1%): Photosensitivity reaction, acne, exfoliative dermatitis, dry skin, herpes simplex, alopecia
• Very rare (less than 0.01%): Cellulitis, petechia, urticaria, herpes zoster, skin hypertrophy, skin ulcer, seborrhea
• Frequency not reported: Sweating
• Postmarketing reports: Stevens-Johnson Syndrome, bullous dermatitis, erythema multiforme, toxic epidermal necrolysis, rash (including erythematous and maculopapular)^[Ref]

Ocular

• Rare (0.01% to 0.1%): Eye pain, abnormality of accommodation, conjunctivitis, keratoconjunctivitis, lacrimation disorder, angle-closure glaucoma
• Very rare (less than 0.01%): Diplopia, blepharitis
• Frequency not reported: Amblyopia
• Postmarketing reports: Glaucoma^[Ref]

Hepatic

• Rare (0.01% to 0.1%): Cholecystitis, liver function tests abnormal
• Very rare (less than 0.01%): Cirrhosis of the liver, AST increased, ALT increased
• Postmarketing reports: Jaundice, hepatitis^[Ref]

Renal

• Rare (0.01% to 0.1%): Kidney calculus, cystitis^[Ref]

Hematologic

• Very rare (less than 0.01%): Lymphadenopathy, leukopenia, anemia, thrombocytopenia, lymphocytosis, pancytopenia
• Frequency not reported: Bone marrow depression (granulocytopenia, agranulocytosis, aplastic anemia, thrombocytopenia), eosinophilia
• Postmarketing reports: Thromboembolic disorder, coagulation disorder^[Ref]

Endocrine

• Very rare (less than 0.01%): Goiter, hypothyroidism
• Frequency not reported: Inappropriate antidiuretic hormone secretion^[Ref]

See also:

Frequently asked questions

• Does Remeron help with sleep?

Further information

Remeron side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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