Amantadine Side Effects

Medically reviewed by Philip Thornton, DipPharm. Last updated on Feb 5, 2024.

Applies to amantadine: oral capsule, oral capsule extended release, oral capsule liquid filled, oral solution, oral syrup, oral tablet, oral tablet extended release.

Serious side effects of Amantadine

Along with its needed effects, amantadine 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 amantadine:

More common

• Bladder pain
• bloody or cloudy urine
• blurred vision
• confusion
• difficult, burning, or painful urination
• dizziness or lightheadedness
• fainting
• falls
• frequent urge to urinate
• lower back or side pain
• seeing, hearing, or feeling things that are not there
• swelling of the hands, feet, or lower legs

Less common

• Inability to move the eyes
• increased blinking or spasms of the eyelid
• muscle spasm
• sticking out of the tongue
• trouble breathing, speaking, or swallowing
• uncontrolled twisting movements of the neck, trunk, arms, or legs
• unusual facial expressions

Rare

• Chills
• decreased vision or any change in vision
• difficulty in coordination
• fever
• increased blood pressure
• increase in body movements
• irritation and swelling of the eye
• loss of memory
• mental depression
• seizures
• severe mood or mental changes
• skin rash
• slurred speech
• sore throat
• thoughts of suicide or attempts at suicide

Other side effects of Amantadine

Some side effects of amantadine 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

• Agitation
• anxiety
• difficulty concentrating
• dry mouth
• headache
• irritability
• loss of appetite
• nausea
• nervousness
• nightmares
• purplish red, net-like, or blotchy spots on the skin
• trouble with sleeping

Less common

• Blindness
• blurred vision
• constipation
• decrease in sexual desire
• decreased vision
• diarrhea
• drowsiness
• dry eyes
• dryness of the mouth, nose, and throat
• false sense of well-being
• joint swelling
• unusual tiredness or weakness
• vomiting

For Healthcare Professionals

Applies to amantadine: compounding powder, oral capsule, oral capsule extended release, oral syrup, oral tablet, oral tablet extended release.

General

The more commonly reported adverse reactions have included nausea, dizziness/lightheadedness, and insomnia.^[Ref]

Nervous system

Common (1% to 10%): Dizziness/lightheadedness, ataxia, headache, somnolence, dystonia

Uncommon (0.1% to 1%): Weakness, slurred speech, hyperkinesia

Rare (less than 0.1%): Convulsion

Frequency not reported: Falling asleep during activities of daily living, withdrawal-emergent hyperpyrexia (a syndrome resembling neuroleptic malignant syndrome)

Postmarketing reports: Coma, delirium, hypokinesia, involuntary muscle contractions, gait abnormalities, paresthesia, EEG changes, tremor^[Ref]

Psychiatric

Very common (10% or more): Hallucinations (up to 21%)

Common (1% to 10%): Insomnia, depression, anxiety, irritability, hallucinations, confusion, nervousness, abnormal dreams, agitation

Uncommon (0.1% to 1%): Psychosis, euphoria, abnormal thinking, amnesia

Rare (less than 0.1%): Suicide attempt, suicide, suicidal ideation

Postmarketing reports: Stupor, delusions, aggressive behavior, paranoid reaction, manic reaction, pathological gambling, increased libido including hypersexuality, and impulse control symptoms^[Ref]

Gastrointestinal

Very common (10% or more): Dry mouth (up to 16%); constipation (up to 13%)

Common (1% to 10%): Nausea, anorexia, diarrhea, decreased appetite

Uncommon (0.1% to 1%): Vomiting

Postmarketing reports: Dysphagia^[Ref]

Cardiovascular

Very common (10% or more): Peripheral edema (up to 16%), orthostatic hypotension (up to 13%)

Uncommon (0.1% to 1%): Congestive heart failure, hypertension

Postmarketing reports: Cardiac arrest, arrhythmias including malignant arrhythmias, hypotension, and tachycardia^[Ref]

Ocular

Common (1% to 10%): Dry eye, cataract, blurred vision

Uncommon (0.1% to 1%): Visual disturbance, punctate subeithelial or other corneal opacity, corneal edema, decreased visual acuity, sensitivity to light, optic nerve palsy

Rare (less than 0.1%): Oculogyric episodes

Postmarketing reports: Keratitis, mydriasis^[Ref]

Other

Very common (10% or more): Fall (up to 13%)

Common (1% to 10%): Fatigue, contusions

Frequency not reported: Death

Postmarketing reports: Fever^[Ref]

Deaths have been reported from overdose with the lowest reported acute lethal dose as 1 gram. Drug overdose has resulted in cardiac, respiratory, renal, or CNS toxicity. Deaths have been reported in patients with renal impairment and attributed to drug accumulation.^[Ref]

Respiratory

Common (1% to 10%): Dry nose, cough

Uncommon (0.1% to 1%): Dyspnea

Postmarketing reports: Acute respiratory failure, pulmonary edema, tachypnea^[Ref]

Hematologic

Rare (less than 0.1%): Leukopenia, neutropenia

Postmarketing reports: Leukocytosis, agranulocytosis^[Ref]

Dermatologic

Common (1% to 10%): Livedo reticularis, pigmentation disorder

Uncommon (0.1% to 1%): Skin rash

Rare (less than 0.1%): Eczematoid dermatitis

Postmarketing reports: Pruritus, diaphoresis^[Ref]

Hypersensitivity

Postmarketing reports: Allergic reactions including anaphylactic reactions^[Ref]

Genitourinary

Common (1% to 10%): Urinary tract infection, benign prostatic hyperplasia

Uncommon (0.1% to 1%): Urinary retention, decreased libido^[Ref]

Renal

Postmarketing reports: Elevated: CPK, BUN, serum creatinine^[Ref]

Hepatic

Rare (less than 0.1%): Reversible liver enzyme elevations

Postmarketing reports: Elevated: alkaline phosphatase, LDH, bilirubin, GGT, SGOT, and SGPT^[Ref]

Musculoskeletal

Common (1% to 10%): Joint swelling, muscle spasms^[Ref]

Frequently asked questions

• What is the difference between Osmolex ER and Gocovri?
• What is Gocovri used to treat?
• Why should you not discontinue amantadine?
• How long does it take for amantadine to start working?
• Why was amantadine discontinued for flu?
• What symptoms does amantadine treat?
• What is Gocovri (amantadine) and how does it work?

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.

Medical Disclaimer