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Remeron Side Effects

Generic Name: mirtazapine

Note: This page contains side effects data for the generic drug mirtazapine. It is possible that some of the dosage forms included below may not apply to the brand name Remeron.

In Summary

Common side effects of Remeron include: severe sedation, increased serum cholesterol, drowsiness, constipation, weight gain, fatigue, insomnia, increased appetite, xerostomia, and decreased appetite. Other side effects include: dizziness, tremor, increased serum triglycerides, palpitations, dyspepsia, vertigo, hot flash, 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

As well as its needed effects, mirtazapine (the active ingredient contained in Remeron) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking mirtazapine, check with your doctor immediately:

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
  • 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

Minor Side Effects

Some mirtazapine side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Constipation
  • dizziness
  • drowsiness
  • dry mouth
  • increased appetite
  • weight gain
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]


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]


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.

It is possible that some side effects of Remeron may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.