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Generic name: amantadinea-MAN-ta-deen ]
Drug classes: Adamantane antivirals, Dopaminergic antiparkinsonism agents

Medically reviewed by on Aug 3, 2023. Written by Cerner Multum.

What is Symmetrel (amantadine)?

Amantadine is an antiviral medicine that blocks the actions of viruses in your body.

Amantadine is used to treat and prevent influenza A (a viral infection). Amantadine may not be effective during every flu season because certain strains of influenza virus may be resistant to this medicine.

Amantadine should not be used in place of getting a yearly flu shot. The Centers for Disease Control recommends an annual flu shot to help protect you each year from new strains of influenza virus.

Amantadine is also used to treat Parkinson's disease and "Parkinson-like" symptoms such as stiffness and shaking that may be caused by the use of certain drugs.

Amantadine may also be used for purposes not listed in this medication guide.

What is the most important information I should know about Symmetrel (amantadine)?

Do not take more than your recommended dose. An amantadine overdose can be fatal.

Do not receive a "live" nasal flu vaccine (FluMist) while taking amantadine, and for at least 48 hours after your last dose. You should not take amantadine if you have received a nasal flu vaccine within the past 14 days.

What should I discuss with my healthcare provider before taking Symmetrel (amantadine)?

You should not use amantadine if you are allergic to it, or:

  • if you have received a nasal flu vaccine (FluMist) within the past 14 days.

To make sure amantadine is safe for you, tell your doctor if you have:

  • epilepsy or other seizure disorder;

  • congestive heart failure;

  • kidney disease;

  • liver disease;

  • low blood pressure or a history of fainting;

  • eczema;

  • glaucoma;

  • a history of alcoholism or drug addiction; or

  • a history of mental illness, psychosis, or suicidal thoughts or actions.

Older adults may be more sensitive to the effects of this medicine.

You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking this medicine. Talk with your doctor if this occurs.

People with Parkinson's disease may have a higher risk of skin cancer (melanoma). Talk to your doctor about this risk and what skin symptoms to watch for.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Amantadine can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.

Amantadine should not be given to a child younger than 1 year old.

How should I take Symmetrel (amantadine)?

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

If you take amantadine to treat influenza A, start taking the medicine within 24 to 48 hours after flu symptoms begin. Keep taking amantadine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared.

If you take this medicine for Parkinson symptoms, your doctor may occasionally change your dose to make sure you get the best results.

Amantadine will not treat an infection caused by bacteria. Call your doctor if your symptoms do not improve, or if you have a fever with a headache, cough, skin rash, or other new symptoms.

If you take amantadine for Parkinson symptoms: You should not stop using amantadine suddenly or your condition may become worse.

Store at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of amantadine can be fatal.

Overdose symptoms may include fever, aggression, behavior changes, hallucinations, severe headache or pounding in your ears, muscle stiffness, problems with balance or walking, fast heart rate, urinating less than usual, trouble breathing, seizure (convulsion), or fainting.

What should I avoid while taking Symmetrel (amantadine)?

Do not receive a "live" nasal flu vaccine (FluMist) while using amantadine, and for at least 48 hours after you stop taking amantadine. The vaccine may not work as well during this time, and may not fully protect you from disease.

Amantadine can cause side effects that may impair your vision, thinking, or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

Drinking alcohol with this medicine can cause side effects.

Avoid taking diet pills, caffeine pills, or other stimulants (such as ADHD medications) without your doctor's advice. Taking a stimulant together with amantadine can increase your risk of unpleasant side effects.

Symmetrel (amantadine) side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • shortness of breath (even with mild exertion), swelling in your hands or feet;

  • painful or difficult urination;

  • depression, agitation, or aggression;

  • behavior changes, hallucinations, thoughts of hurting yourself;

  • a seizure (convulsions); or

  • severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Common side effects may include:

  • dizziness;

  • nausea; or

  • sleep problems (insomnia).

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 other drugs will affect Symmetrel (amantadine)?

Other drugs may interact with amantadine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Date modified: October 13, 2017
Last reviewed: November 25, 2015

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.