Symmetrel : Uses, Side Effects, Interactions & More

Why is this medication prescribed?

Symmetrel (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. It is also used to prevent symptoms of influenza A virus infection and to treat respiratory infections caused by influenza A virus. Symmetrel belongs to a class of medications called adamantanes. It is believed to work to control movement problems by increasing the amount of dopamine in certain parts of the body. It works against the influenza A virus by stopping the spread of the virus in the body.

How should this medicine be used?

Symmetrel (Amantadine) comes as a capsule, an extended-release capsule (Gocovri), a tablet, and a liquid to take by mouth. Capsules, tablets, and liquid medications are usually taken once or twice a day. The extended-release capsules are taken once a day before going to bed. Take Symmetrel at around the same times every day. Follow the directions on your prescription label carefully and ask your doctor or pharmacist to explain any parts you do not understand. Take Symmetrel exactly as directed. Do not take more or less, or take it more often than prescribed by your doctor.

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

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

Do not stop taking Symmetrel without consulting your doctor. If you stop taking Symmetrel suddenly, you may experience fever, confusion, changes in mental status, or severe muscle stiffness. Your doctor will likely reduce 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 Symmetrel,

  • Tell your doctor and pharmacist if you are allergic to Symmetrel, any other medications, or any of the ingredients in Symmetrel capsules, extended-release capsules, 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 (Diamox); antihistamines; cotrimoxazole (Bactrim, Septra, Sulfatrim); dichlorphenamide (Daranide); hydrochlorothiazide with triamterene (Maxzide, Dyazide); Ipratropium (Atrovent); medications for irritable bowel disease, mental illness, motion sickness, sleep or urinary problems; other medications to treat Parkinson’s disease; methazolamide (GlaucTabs, Neptazane); quinine (Qualaquin); quinidine; sedative sodium bicarbonate (Alka-Seltzer, in Zegerid); stimulants; or thioridazine (Mellaril). Your doctor may need to change the doses of your medications or monitor you closely for side effects.
  • Tell your doctor if you have kidney disease. Your doctor may tell you not to take Symmetrel.
  • Tell your doctor if you drink or have ever had large amounts of alcohol, use or have ever used illegal drugs, or have overused prescription drugs, or if you have or have ever had epilepsy or any other seizures, disorders sleep disorders, urinary tract infections, mental illness, glaucoma (a condition in which increased pressure in the eye can cause gradual loss of vision), eczema (atopic dermatitis; a skin condition that causes skin is dry and itchy and sometimes becomes 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 Symmetrel, call your doctor immediately. Symmetrel can harm the fetus.
  • If you are having surgery, including dental surgery, tell the doctor or dentist that you are taking Symmetrel.
  • You should know that Symmetrel may make you drowsy or have blurred vision. Do not drive a car, operate machinery, or participate in potentially dangerous activities until you know how this drug affects you.
  • Ask your doctor about the safe use of alcoholic beverages while taking Symmetrel. Alcohol can make the side effects of Symmetrel worse.
  • You should know that Symmetrel can cause dizziness, lightheadedness, and fainting when you get up too quickly from lying down. This is more common when you first start taking Symmetrel 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.
  • Don’t get vaccinated without checking with your doctor.
  • You should know that some people taking Symmetrel and other similar medicines used to treat Parkinson’s disease have developed gambling problems or have had other intense urges or behaviors that were compulsive or unusual for them, such as increased sexual need, binge eating, or uncontrolled spending. Call your doctor if you have a gambling urge that is difficult to control, you have strong urges, or you cannot control your behavior. Inform your family members of this risk so they can call the doctor even if you don’t realize that your gambling or any other intense urges or unusual behavior has 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. 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 the one you forgot.

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

What side effects can this medication cause?

Symmetrel 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

Symmetrel can cause other side effects. Call your doctor if you have any unusual problems while taking this medicine.

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

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

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

It is important to keep all medicines out of the sight and reach of children, since many containers (such as those containing weekly pills and those for eye drops, creams, patches and inhalers) are not resistant to children and small children can easily open them. To protect young children from poisoning, always close the safety caps and immediately place the medicine in a safe place, one that is upright and out of their sight and reach.

Unnecessary medications must be disposed of in special ways to ensure they cannot be consumed by pets, children, and others. However, you should not flush this medicine down the toilet. Instead, the best way to dispose of your medications is through a drug take-back program. Talk to your pharmacist or contact your local garbage / recycling department to find out about take-back programs in your community. Check out the FDA drug safe disposal 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 collapsed, had a seizure, has trouble breathing, or cannot wake up, immediately call 911 for emergency services.

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
  • restlessness or difficulty concentrating
  • depression
  • lack of energy

What other information should I know?

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

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

It is important that you keep a written list of all prescription and over-the-counter (over-the-counter) medications you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should take this list with you every time you visit a doctor or if you go into hospital. It is also important information to take with you in case of emergencies.

Brand Names

  • Gocovri®
  • Symadine®
  • Symmetrel®

Other Names

  • Adamantanamine Hydrochloride

Disclaimer: We have made every effort to ensure that all information is factually accurate, comprehensive and up-to-date. However, this article should not be used as a licensed health care professional’s choice of knowledge and expertise. You should always consult your doctor or other health care professional before taking any medication. The information given here is subject to change and it has not been used to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions or adverse effects. The lack of warning or other information for any drug does not indicate that the combination of medicine or medication is safe, effective or appropriate for all patients or all specific uses.

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