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Mirtazapine Side Effects

In Summary

Commonly reported side effects of mirtazapine include: severe sedation, constipation, drowsiness, increased serum cholesterol, weight gain, fatigue, insomnia, increased appetite, xerostomia, and decreased appetite. Other side effects include: dizziness, increased serum triglycerides, tremor, dyspepsia, hot flash, palpitations, vertigo, abnormal dreams, bitter taste, decreased libido, and diaphoresis. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to mirtazapine: oral tablet, oral tablet disintegrating

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:

Less Common

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

Rare

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

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

Less Common

  • Abdominal or stomach pain
  • 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
  • trembling or shaking
  • vomiting
  • weakness

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]

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]

References

1. Cerner Multum, Inc. "Australian Product Information." O 0

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. "Product Information. Remeron (mirtazapine)." Organon, West Orange, NJ.

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.

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