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Symmetrel (Generic Amantadine)

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Why is this medication prescribed?

Amantadine is used to treat the symptoms of Parkinson’s disease (PD; a disorder of the nervous system that causes difficulties with movement, muscle control, and balance) and other similar conditions. It is also used to control movement problems that are a side effect of certain medications used to treat Parkinson’s disease. Amantadine extended-release capsules (Gocovri) are used along with the combination of levodopa and carbidopa (Rytary, Sinemet) to treat ”off” episodes (times of difficulty moving, walking, and speaking that may happen when other medications wear off) in people with Parkinson’s disease. It also is used to prevent symptoms of influenza A virus infection and for treatment of respiratory infections caused by influenza A virus. Amantadine is in a class of medications called adamantanes. It is thought to work to control movement problems by increasing the amount of dopamine in certain parts of the body. It works against influenza A virus by stopping the spread of the virus in the body.

How should this medicine be used?

Amantadine comes as a capsule, extended-release capsule (Gocovri), tablet, extended-release tablet (Osmolex), and liquid to take by mouth. The capsules, tablets, and liquid medications are usually taken once or twice a day. The extended-release capsules are usually taken once a day at bedtime. The extended-release tablets are usually taken once a day in the morning. Take amantadine at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take amantadine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the extended-release capsules and extended-release tablets whole; do not split, chew, or crush them. If you have difficulty swallowing the extended-release capsule, you may open the capsule and sprinkle the entire contents on a teaspoonful of soft food, like applesauce. Eat the mixture right away and swallow without chewing.

If you are taking amantadine for Parkinson’s disease, your doctor may start you on a low dose of amantadine and gradually increase your dose.

Do not stop taking amantadine without talking to your doctor. If you suddenly stop taking amantadine, you may experience fever, confusion, changes in mental state, or severe muscle stiffness. Your doctor will probably decrease your dose gradually.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.

Other uses for this medicine

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before taking amantadine,

  • Tell your doctor and pharmacist if you are allergic to amantadine, any other medications, or any of the ingredients in amantadine capsules, extended-release capsules, tablets, extended-release tablets, or liquid. Ask your pharmacist for a list of the ingredients.
  • Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: acetazolamide; antihistamines; dichlorphenamide; hydrochlorothiazide with triamterene (Maxzide, Dyrenium); medications for mental illness, motion sickness, sleep, or urinary problems; other medications to treat Parkinson’s disease; methazolamide; quinine (Qualaquin); quinidine (in Nuedexta); sedatives; sodium bicarbonate (Alka-Seltzer, in Zegerid); stimulants; or thioridazine. Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with amantadine, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • Tell your doctor if you have kidney disease. Your doctor may tell you not to take amantadine.
  • Tell your doctor if you drink or have ever drunk large amounts of alcohol, use or have ever used street drugs, or have overused prescription medications or if you have or have ever had depression, unusual changes in behavior or mood, mental illness, or thoughts about or attempted suicide; epilepsy or any other type of seizures; a sleep disorder; urinary tract infections; glaucoma (a condition in which increased pressure in the eye can lead to gradual loss of vision); eczema (atopic dermatitis; a skin disease that causes the skin to be dry and itchy and to sometimes develop red, scaly rashes); heart failure; swelling of the hands, feet, ankles, or lower legs; low blood pressure; or liver disease.
  • Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking amantadine, call your doctor immediately. Amantadine may cause harm to the fetus.
  • You should know that amantadine may make you drowsy or cause blurred vision. Do not drive a car, operate machinery, or participate in potentially dangerous activities until you know how this medication affects you.
  • You should know that amantadine may cause dizziness, lightheadedness, and fainting when you get up too quickly from a lying position. This is more common when you first start taking amantadine or if your dose has been increased. To avoid this problem, get out of bed slowly, resting your feet on the floor for a few minutes before standing up.
  • Do not have any vaccinations without talking to your doctor.
  • You should know that some people taking amantadine and other similar medications used to treat Parkinson’s disease, have developed gambling problems or had other intense urges or behaviors that were compulsive or unusual for them, such as increased sexual urges, binge eating, or uncontrolled spending. Call your doctor if you have an urge to gamble that is difficult to control, you have intense urges, or you are unable to control your behavior. Tell your family members about this risk so that they can call the doctor even if you do not realize that your gambling or any other intense urges or unusual behaviors have become a problem.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget a dose?

If you are taking the capsules, tablets, or liquid, take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

If you are taking the extended-release capsules or the extended-release tablets, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one. If you have forgotten to take the extended-release capsules or extended-release tablets for several days, call your doctor.

What side effects can this medication cause?

Amantadine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • Dry mouth
  • Constipation
  • Nausea
  • Vomiting
  • Decreased appetite
  • Difficulty falling asleep or staying asleep
  • Abnormal dreams
  • Headache
  • Confusion
  • Drowsiness
  • Tiredness
  • Uncontrollable tightening of muscles, change from normal walking, and falls
  • Lace-like purple pattern on skin

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:

  • Hallucinations (seeing things or hearing voices that do not exist)
  • Believing things that are not true
  • Not trusting others or feeling that others want to hurt you
  • Depression
  • Anxiety
  • Suicidal (thinking about harming or killing oneself or planning or trying to do so)
  • Lack of interest, enthusiasm, or concern
  • Dizziness, lightheadedness, fainting, or blurred vision
  • Swelling of the hands, feet, ankles, or lower legs
  • Difficulty urinating
  • Shortness of breath

Amantadine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website ( for more information if you do not have access to a take-back program.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Symptoms of overdose may include the following:

  • Irregular or fast heartbeat
  • Difficulty breathing
  • Decreased urination
  • Swelling of the hands, feet, ankles or lower legs
  • Stiff or rigid arms or legs
  • Uncontrollable movements or shaking of a part of the body
  • Problems with coordination
  • Confusion
  • Feeling like you are looking at yourself as an outside observer
  • Fear, irritability, or aggressive behavior
  • Seeing things or hearing voices that do not exist
  • Lack of energy

What other information should I know?

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your response to amantadine.

If you are taking the extended-release tablets (Osmolex), you may notice something that looks like a tablet in your stool. This is just the empty tablet shell, and does not mean that you did not get your complete dose of medication.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Gocovri®
  • Osmolex ER®
  • Symadine®
  • Symmetrel®
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