Generic Name: amantadine (Oral route)
Medically reviewed on March 25, 2018.
The Symmetrel brand name has been discontinued in the U.S. If generic versions of this product have been approved by the FDA, there may be generic equivalents available.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
- Capsule, Extended Release
- Capsule, Liquid Filled
Therapeutic Class: Antiparkinsonian
Pharmacologic Class: Anticholinergic
Chemical Class: Adamantane
Uses For Symmetrel
Amantadine is an antiviral medicine. It is used to prevent or treat certain influenza (flu) infections (type A). It may be given alone or together with flu shots. Amantadine will not work for colds, other types of flu, or other virus infections.
Amantadine is also an antidyskinetic medicine. It is used to treat Parkinson's disease (sometimes called "paralysis agitans" or "shaking palsy") and its symptoms, including dyskinesia (sudden uncontrolled movements). It may be given alone or in combination with other medicines (eg, levodopa) for Parkinson's disease. By improving muscle control and reducing stiffness, this medicine allows more normal movements of the body as the disease symptoms are reduced. Amantadine is also used to treat stiffness and shakiness caused by certain medicines that are used to treat nervous, mental, and emotional conditions.
This medicine is available only with your doctor's prescription.
Before Using Symmetrel
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of Symmetrel® in children. Safety and efficacy have not been established in children younger than 1 year of age.
Appropriate studies have not been performed on the relationship of age to the effects of Gocovri® in the pediatric population. Safety and efficacy have not been established.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of amantadine in the elderly. However, elderly patients are more likely to have age-related kidney, liver, or heart disease, which may require an adjustment in the dose for patients receiving Symmetrel®. Elderly patients are also more likely to have unwanted effects (eg, falls, hallucinations) and age-related kidney disease, which may require caution in patients receiving Gocovri®.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with Medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- Potassium Chloride
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Betel Nut
Interactions with Food/Tobacco/Alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Other Medical Problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Congestive heart failure or
- Eczema, recurrent, history of or
- Epilepsy or seizures, history of or
- Hypotension (low blood pressure) or
- Liver disease or
- Neuroleptic malignant syndrome (NMS), history of or
- Peripheral edema (swelling of the hands, ankles, or feet) or
- Psychosis (mental illness), history of—Use with caution. May make these conditions worse.
- End-stage kidney disease or
- Glaucoma, angle-closure, untreated (narrow-angle glaucoma)—Should not be used in patients with these conditions.
- Kidney disease—Use with caution. The effects of this medicine may be increased because of slower removal from the body.
Proper Use of amantadine
This section provides information on the proper use of a number of products that contain amantadine. It may not be specific to Symmetrel. Please read with care.
For patients taking amantadine to prevent or treat flu infections:
- Talk to your doctor about the possibility of getting a flu shot if you have not had one yet.
- This medicine is best taken before exposure or right away after exposure to people who have the flu.
- To help keep yourself from getting the flu, keep taking this medicine for the full time of treatment. Or if you already have the flu, continue taking this medicine for the full time of treatment even if you begin to feel better after a few days. This will help clear up your infection completely. If you stop taking this medicine too soon, your symptoms may return. This medicine should be taken for at least 2 days after all your flu symptoms have disappeared.
- This medicine works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times at day and night. For example, if you are to take two doses a day, the doses should be spaced about 12 hours apart. If this interferes with your sleep or other daily activities, or if you need help in planning the best times to take your medicine, check with your doctor.
- If you are using the oral liquid form of amantadine, use a marked measuring spoon, oral syringe, or medicine cup to measure each dose correctly. The average household teaspoon may not hold the right amount of liquid.
For patients taking amantadine for Parkinson's disease or movement problems (including dyskinesia) caused by certain medicines used to treat nervous, mental, and emotional conditions:
- Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.
- This medicine comes with a Medication Guide. Read and follow these instructions carefully. Ask your doctor if you have any questions.
- Do not stop using this medicine suddenly without asking your doctor. You may need to slowly decrease your dose before stopping it completely.
- Improvement in the symptoms of Parkinson's disease usually occurs in about 2 days. However, in some patients, this medicine must be taken for up to 2 weeks before the full benefit is seen.
Take Gocovri® extended-release capsules at bedtime. Swallow whole. Do not crush, break, or chew it. You may also open and sprinkle the extended-release capsules on a teaspoonful of soft food, including applesauce. Take all of the medicine right away without chewing.
Do not use Symmetrel® if you have received the nasal flu vaccine (live attenuated influenza vaccine) in the past 2 weeks or if you will receive the vaccine within 48 hours, unless your doctor says it is okay.
Do not drink alcohol while you are using this medicine.
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For the treatment or prevention of flu:
- For oral dosage forms (capsules, syrup, and tablets):
- Adults—200 milligrams (mg) or four teaspoonfuls once a day as a single dose.
- Older adults—100 milligrams (mg) once a day as a single dose.
- Children 9 to 12 years of age—100 milligrams (mg) or two teaspoonfuls two times a day.
- Children 1 to 9 years of age—Dose is based on body weight and must be determined by your doctor. The usual dose is 4.4 to 8.8 milligrams (mg) per kilogram (kg) of body weight per day. The dose is divided evenly and given two times a day. However, the dose is usually not more than 150 mg per day.
- Children younger than 1 year of age—Use and dose must be determined by your doctor.
- For oral dosage forms (capsules, syrup, and tablets):
- For treatment of Parkinson's disease or movement problems (including dyskinesia):
- For oral dosage forms (extended-release capsules):
- Adults—137 milligrams (mg) once a day at bedtime. Your doctor may increase your dose to 274 mg (two 137 mg capsules) once a day at bedtime after one week.
- Children—Use and dose must be determined by your doctor.
- For oral dosage forms (liquid-filled capsules, syrup, and tablets):
- Adults—100 milligrams (mg) two times a day. Your doctor may adjust your dose if needed.
- Older adults—At first, 100 milligrams (mg) once a day as a single dose. Your doctor may adjust your dose if needed.
- Children—Use and dose must be determined by your doctor.
- For oral dosage forms (extended-release capsules):
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
If you miss a dose of Gocovri®, skip the missed dose and take your next dose at your usual time. Do not take extra medicine to make up for a missed dose.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions While Using Symmetrel
It is very important that your doctor check your progress at regular visits to allow changes in your dose and to check for any unwanted effects.
Amantadine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. Also tell your doctor if you have sudden or strong feelings, such as feeling nervous, angry, restless, violent, or scared. If you, your child, or your caregiver notice any of these adverse effects, tell your doctor or your child's doctor right away.
Some people who have used this medicine had unusual changes in their behavior. Talk with your doctor right away if you start having problems with gambling or an increased interest in sex while using this medicine.
Drinking alcoholic beverages while taking this medicine may cause increased side effects, such as circulation problems, dizziness, lightheadedness, fainting, or confusion. Do not drink alcoholic beverages while you are taking this medicine.
This medicine may cause some people to become dizzy, drowsy, or lightheaded, or to have blurred vision or trouble concentrating. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
Dizziness, lightheadedness, or fainting may occur with this medicine, especially when you suddenly get up from a lying or sitting position. These symptoms are more likely to occur when you begin taking this medicine or when the dose is increased. Getting up slowly may help. If this problem continues or gets worse, check with your doctor.
Patients with Parkinson's disease must be careful not to overdo physical activities when their condition improves and body movements become easier, since injuries resulting from falls may occur. Such activities must be gradually increased to give your body time to adjust to a change in balance, circulation, and coordination.
Amantadine may cause dryness of the mouth, nose, and throat. For temporary relief of mouth dryness, use sugarless candy or gum, melted bits of ice in your mouth, or use a saliva substitute. If your mouth continues to feel dry for more than 2 weeks, check with your doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.
This medicine may cause purplish red, net-like, blotchy spots on the skin. This problem occurs more often in females and usually occurs on the legs or feet after this medicine has been taken regularly for a month or more. Although the blotchy spots may remain as long as you are taking this medicine, they will usually go away gradually within 2 to 12 weeks after you stop taking the medicine. If you have any questions about this, talk with your doctor.
Check with your doctor right away if you are having convulsions (seizures), difficulty with breathing, a fast heartbeat, a high fever, high or low blood pressure, increased sweating, loss of bladder control, severe muscle stiffness, unusually pale skin, or tiredness. These could be symptoms of a serious condition called neuroleptic malignant syndrome (NMS).
If you are using this medicine for Parkinson's disease, do not stop taking this medicine suddenly without first checking with your doctor. Your doctor may want you to slowly reduce the amount you are using before stopping it completely.
If you are using this medicine for Parkinson's disease, it is important that your doctor check your skin regularly for signs of melanoma (skin cancer). If you notice any unusual red, brown, or black spots on your skin, check with your doctor right away.
If your Parkinson's symptoms do not improve within a few days, if they become worse, or if this medicine appears less effective after a few weeks, check with your doctor.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
Symmetrel Side Effects
Along with its needed effects, a medicine 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:More common
- Bladder pain
- bloody or cloudy urine
- blurred vision
- difficult, burning, or painful urination
- dizziness or lightheadedness
- 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
- Inability to move the eyes
- increased blinking or spasms of the eyelid
- muscle spasm
- sticking out of the tongue
- troubled breathing, speaking, or swallowing
- uncontrolled twisting movements of the neck, trunk, arms, or legs
- unusual facial expressions
- decreased vision or any change in vision
- difficulty in coordination
- increased blood pressure
- increase in body movements
- irritation and swelling of the eye
- loss of memory
- mental depression
- severe mood or mental changes
- skin rash
- slurred speech
- sore throat
- thoughts of suicide or attempts at suicide
Some side effects 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
- difficulty concentrating
- loss of appetite
- purplish red, net-like, or blotchy spots on the skin
- trouble with sleeping
- decrease in sexual desire
- dryness of the mouth, nose, and throat
- false sense of well-being
- unusual tiredness or weakness
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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More about Symmetrel (amantadine)
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Support Group
- 2 Reviews – Add your own review/rating
- Drug class: adamantane antivirals
Other brands: Gocovri