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Osmolex ER

Last reviewed on RxList: 3/2/2018
Osmolex ER Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 3/2/2018

Osmolex ER (amantadine extended-release tablets) is indicated for the treatment of drug-induced extrapyramidal reactions in adult patients with Parkinson's disease. Common side effects of Osmolex ER include

  • nausea,
  • dizziness,
  • lightheadedness,
  • insomnia,
  • depression,
  • anxiety and irritability,
  • hallucinations,
  • confusion,
  • loss of appetite,
  • dry mouth,
  • constipation,
  • loss of coordination,
  • mottled purplish skin discoloration,
  • swelling of extremities,
  • dizziness on standing,
  • headache,
  • drowsiness,
  • nervousness,
  • strange dreams,
  • agitation,
  • dry nose,
  • diarrhea,
  • and fatigue

The initial dosage of Osmolex ER is 129 mg orally once daily in the morning. The dosage may be increased in weekly intervals to a maximum daily dose of 322 mg once daily in the morning. Osmolex ER may interact with anticholinergic drugs, drugs affecting urinary pH (e.g., carbonic anhydrase inhibitors, sodium bicarbonate), live influenza vaccines, and alcohol. Tell your doctor all medications and supplements you use. Osmolex ER is not recommended for use during pregnancy; it may harm a fetus. Osmolex ER passes into breast milk but its effects on nursing infants is unknown. Consult your doctor before breastfeeding. Withdrawal symptoms such as:

  • fever,
  • confusion,
  • severe muscle stiffness,
  • psychosis,
  • personality changes,
  • agitation,
  • aggressive behavior,
  • hallucinations,
  • paranoia,
  • other psychotic or paranoia reactions may occur if you suddenly stop taking Osmolex ER.
Medical Editor: John P. Cunha, DO, FACOEP

Our Osmolex ER (amantadine extended-release tablets) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Parkinson's disease is only seen in people of advanced age. See Answer
Osmolex ER Professional Information


The following serious adverse reactions are described elsewhere in the labeling:

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Immediate-Release Amantadine

The adverse reactions listed in Table 2 were identified in clinical studies of immediate-release amantadine. The most common adverse reactions reported in ≥5% of patients at the recommended dosage of immediate-release amantadine were nausea, dizziness/lightheadedness, and insomnia.

Table 2: Incidence of Adverse Reactions from Pooled Studies of Immediate-Release Amantadine

5 to 10% 1 to 5% 0.1 to 1% Less than 0.1%
Nausea Depression Congestive heart failure Convulsion
Dizziness/ lightheadedness Anxiety and irritability Psychosis Leukopenia
Insomnia Hallucinations Urinary retention Neutropenia
  Confusion Dyspnea Eczematoid dermatitis
  Anorexia Skin rash Oculogyric episodes
  Dry mouth Vomiting Suicidal attempt
  Constipation Weakness Suicide
  Ataxia Slurred speech Suicidal ideation
  Livedo reticularis Euphoria  
  Peripheral edema Thinking abnormality  
  Orthostatic hypotension Amnesia  
  Headache Hyperkinesia  
  Somnolence Hypertension  
  Nervousness Decreased libido  
  Dream abnormality Visual disturbance  
  Agitation Punctate subepithelial or other corneal opacity  
  Dry nose Corneal edema  
  Diarrhea Decreased visual acuity  
  Fatigue Sensitivity to light  
    Optic nerve palsy  

Read the entire FDA prescribing information for Osmolex ER (Amantadine)


Dementia, Alzheimer's Disease, and Aging Brains See Slideshow
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© Osmolex ER Patient Information is supplied by Cerner Multum, Inc. and Osmolex ER Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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