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Remeron Side Effects

Generic name: mirtazapine

Medically reviewed by Last updated on Apr 21, 2023.

Note: This document contains side effect information about mirtazapine. Some dosage forms listed on this page may not apply to the brand name Remeron.

Applies to mirtazapine: oral tablet, oral tablet disintegrating.


Oral route (Tablet; Tablet, Disintegrating)

Suicidal Thoughts and BehaviorsIncreased risk of suicidal thoughts and behavior in pediatric and young adult patients taking antidepressants. Closely monitor all antidepressant-treated patients for clinical worsening and emergence of suicidal thoughts and behaviors. Mirtazapine is not approved for use in pediatric patients..

Serious side effects of Remeron

Along with its needed effects, mirtazapine (the active ingredient contained in Remeron) 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:

Less common

  • Decreased or increased movement
  • mood or mental changes, including abnormal thinking, agitation, anxiety, confusion, and feelings of not caring
  • skin rash
  • swelling
  • trouble breathing


  • Change in menstrual cycle (periods)
  • chills
  • decreased sexual ability
  • fever
  • menstrual pain
  • mood or mental changes, including anger, feelings of being outside the body, mood swings, and unusual excitement
  • mouth sores
  • seeing, hearing, or feeling things that are not there
  • seizures
  • sore throat

Incidence not known

  • Black, tarry stools
  • blistering, peeling, loosening of skin
  • chest pain
  • fainting
  • hives, itching, skin rash
  • irregular or slow heart rate
  • joint or muscle pain
  • painful or difficult urination
  • red, irritated eyes
  • red skin lesions, often with a purple center
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Other 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:

More common

  • Constipation
  • dizziness
  • drowsiness
  • dry mouth
  • increased appetite
  • weight gain

Less common

  • Abnormal dreams
  • back pain
  • dizziness or fainting when getting up suddenly from a lying or sitting position
  • increased need to urinate
  • increased sensitivity to touch
  • increased thirst
  • low blood pressure
  • muscle pain
  • nausea
  • sense of constant movement of self or surroundings
  • stomach pain
  • trembling or shaking
  • vomiting

Incidence not known

  • Painful or prolonged erection of the penis
  • swelling of the breasts or unusual milk production

For Healthcare Professionals

Applies to mirtazapine: oral tablet, oral tablet disintegrating.

Nervous system

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]


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]


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]


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]


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]


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]


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]


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]


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]


Common (1% to 10%): Influenza/flu syndrome

Frequency not reported: Infection[Ref]


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]


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]


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]


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


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]


Very rare (less than 0.01%): Goiter, hypothyroidism

Frequency not reported: Inappropriate antidiuretic hormone secretion[Ref]

Frequently asked questions


1. Product Information. Remeron (mirtazapine). Organon. 2001.

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

3. Cerner Multum, Inc. Australian Product Information.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.