"Flu viruses are constantly changing so it's not unusual for new flu virus strains to appear each year. For more information about how flu viruses change, visit How the Flu Virus Can Change www.cdc.gov/flu/about/viruses/change.htm.
Symmetrel Side Effects Center
Medical Editor: John P. Cunha, DO, FACOEP
Symmetrel (amantadine hydrochloride) is prescribed to prevent or treat symptoms of infection caused by strains of influenza A virus. Symmetrel is also used in the treatment of Parkinson's Disease and similar conditions. Symmeterel is available in generic form. The most common side effects are nausea, dizziness, and insomnia. Less common side effects may occur.
The adult daily dosage of Symmeterel is 200 mg per day, taken orally. The dose for patients over 65 is 100 mg per day, and the pediatric dose is calculated based on the child's weight. Doses may be modified based on your medical condition and your response to therapy. Do not take Symmeterel if you have taken flu vaccine inhaled through the nose, as serious adverse reactions may occur. Symmeterel should not be used during pregnancy unless needed as it can cause heart defects in the fetus. It is not recommended for women who are nursing as it can pass into breast milk. Do not suddenly stop taking Symmeteral as symptoms or side effects may worsen.
Our Symmetrel 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.
What is Patient Information in Detail?
Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.
Symmetrel in Detail - Patient Information: Side Effects
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have any of these serious side effects:
- feeling short of breath, even with mild exertion;
- swelling, rapid weight gain;
- feeling depressed, agitated, or aggressive;
- behavior changes, hallucinations, thoughts of hurting yourself;
- urinating less than usual or not at all;
- high fever, stiff muscles, confusion, sweating, fast or uneven heartbeats, rapid breathing, feeling like you might pass out;
- restless muscle movements in your eyes, tongue, jaw, or neck; or
- tremor (uncontrolled shaking).
Less serious side effects may include:
- dizziness, drowsiness, headache;
- sleep problems (insomnia), strange dreams;
- feeling nervous;
- nausea, diarrhea, constipation, loss of appetite;
- dry mouth, dry nose; or
- loss of balance or coordination.
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. You may report side effects to FDA at 1-800-FDA-1088.
Read the entire detailed patient monograph for Symmetrel (Amantadine Hydrochloride)
What is Patient Information Overview?
A concise overview of the drug for the patient or caregiver from First DataBank.
Symmetrel Overview - Patient Information: Side Effects
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor immediately if any of these unlikely but serious side effects occur: purplish-red blotchy spots on the skin, swelling of the ankles/feet, difficulty urinating, vision changes.
Tell your doctor immediately if any of these rare but very serious side effects occur: shortness of breath, mental/mood changes (such as depression, suicidal thoughts/attempts), muscle stiffness, uncontrolled muscle movements, unusual sweating, fast heartbeat, unexplained fever, unusual strong urges (such as increased gambling, increased sexual urges), seizures.
A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
Some people taking amantadine have fallen asleep suddenly during their usual daily activities (such as talking on the phone, driving). In some cases, sleep occurred without any feelings of drowsiness beforehand. This sleep effect may occur anytime during treatment with amantadine, including up to 1 year after starting the medication. If you experience increased sleepiness or fall asleep during the day, do not drive or take part in other possibly dangerous activities until you have discussed this effect with your doctor. Your risk of this sleep effect is increased by using alcohol or other medications that can make you drowsy. See also Precautions section.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Read the entire patient information overview for Symmetrel (Amantadine Hydrochloride)
What is Prescribing information?
The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.
Symmetrel FDA Prescribing Information: Side Effects
Less frequently (1-5%) reported adverse reactions are: depression, anxiety and irritability, hallucinations, confusion, anorexia, dry mouth, constipation, ataxia, livedo reticularis, peripheral edema, orthostatic hypotension, headache, somnolence, nervousness, dream abnormality, agitation, dry nose, diarrhea and fatigue.
Infrequently (0.1-1%) occurring adverse reactions are: congestive heart failure, psychosis, urinary retention, dyspnea, skin rash, vomiting, weakness, slurred speech, euphoria, thinking abnormality, amnesia, hyperkinesia, hypertension, decreased libido, and visual disturbance, including punctate subepithelial or other corneal opacity, corneal edema, decreased visual acuity, sensitivity to light, and optic nerve palsy.
Rare (less than 0.1%) occurring adverse reactions are: instances of convulsion, leukopenia, neutropenia, eczematoid dermatitis, oculogyric episodes, suicidal attempt, suicide, and suicidal ideation (see WARNINGS).
Other adverse reactions reported during postmarketing experience with SYMMETREL (amantadine hydrochloride) usage include:
coma, stupor, delirium, hypokinesia, hypertonia, delusions, aggressive behavior, paranoid reaction, manic reaction, involuntary muscle contractions, gait abnormalities, paresthesia, EEG changes, and tremor. Abrupt discontinuation may also precipitate delirium, agitation, delusions, hallucinations, paranoid reaction, stupor, anxiety, depression and slurred speech;
Skin and Appendages
pruritus and diaphoresis;
neuroleptic malignant syndrome (see WARNINGS), allergic reactions including anaphylactic reactions, edema, fever, pathological gambling, increased libido including hypersexuality, and impulse control symptoms.
Read the entire FDA prescribing information for Symmetrel (Amantadine Hydrochloride)
Additional Symmetrel Information
Symmetrel - User Reviews
Symmetrel User Reviews
Now you can gain knowledge and insight about a drug treatment with Patient Discussions.
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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