Amantadine is used to prevent or treat a certain type of flu (influenza A). If you have been infected with the flu, this medication may help make your symptoms less severe and shorten the time it will take you to get better. Taking amantadine if you have been or will be exposed to the flu may help to prevent you from getting the flu. This medication is an antiviral that is believed to work by stopping growth of the flu virus. This medication is not a vaccine. To increase the chance that you will not get the flu, it is important to get a flu shot once a year at the beginning of every flu season, if possible.
Based on the recommendation from the Centers for Disease Control (CDC) in the US, amantadine should not be used to treat or prevent influenza A because the current influenza A virus in the United States and Canada is resistant to this medication. For more details, talk to your doctor or pharmacist.
Amantadine is also used to treat Parkinson's disease, as well as side effects caused by drugs (e.g., drug-induced extrapyramidal symptoms), chemicals, other medical conditions. In these cases, this medication may help to improve your range of motion and ability to exercise. For the treatment of these conditions, amantadine is believed to work by restoring the balance of natural chemicals (neurotransmitters) in the brain.
How to use Symmetrel Capsule
Take this medication by mouth with or without food, usually once or twice daily or as directed by your doctor. If you are taking this medication twice a day and have trouble sleeping after taking it, take the second dose several hours before bedtime.
If you are using the liquid form of this medication, carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.
Dosage is based on your medical condition and response to therapy. In children, the dosage is also based on body weight. Do not take more than prescribed by your doctor.
This medication works best when the amount of medicine in your body is kept at a constant level. Therefore, take this medication at evenly spaced intervals throughout the day and night.
If you are taking amantadine for a viral infection, begin taking it as soon as possible. Continue taking it until the full prescribed amount is finished, even if symptoms disappear after a few days. Stopping the medication too early may result in a relapse of the infection.
In Parkinson's disease, the effects of the medication may not be noticed for several weeks. Do not suddenly stop taking the medication because symptoms or side effects may worsen. Your doctor may want to reduce your dose gradually. This medication may not work as well after it has been taken for several months. Tell your doctor if this medication stops working well.
Blurred vision, nausea, stomach upset, drowsiness, dizziness, headache, dry mouth, constipation, nervousness, or trouble sleeping may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.
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 right away 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 even if you have used this medication for a long time. 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 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Before taking amantadine, tell your doctor or pharmacist if you are allergic to it; or to rimantadine; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: a certain type of eye disease (untreated closed-angle glaucoma).
Before using this medication, tell your doctor or pharmacist your medical history, especially of: swelling of arms/legs (peripheral edema), heart problems (e.g., congestive heart failure), blood pressure problems (e.g., dizziness when standing), kidney disease, liver disease, mental/mood conditions (e.g., depression, psychosis), seizures, a certain skin condition (eczematoid dermatitis).
This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis). See also Side Effects section.
To minimize dizziness and lightheadedness, get up slowly when rising from a seated or lying position.
If you are taking this medication for Parkinson's disease, be careful not to overdo physical activity as your condition improves because this may increase your risk of falls. Consult your doctor about a plan to gradually increase your physical activity as symptoms improve.
This medication should be used during pregnancy only if clearly needed. There are rare reports of heart defects in newborns whose mothers took amantadine during pregnancy. Discuss the risks and benefits with your doctor.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Amantadine may interfere with the effect of certain vaccines, such as flu vaccine inhaled through the nose. However, you may get a flu shot (flu vaccine given by injection) if recommended by your doctor.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include fast/irregular heartbeats, severe drowsiness, shortness of breath, change in the amount of urine, mental/mood changes (e.g., anxiety, aggression, confusion, hallucinations), seizures.
Do not share this product with others.
People with Parkinson's disease may have an increased risk for developing skin cancer (melanoma). If you are taking this drug to treat Parkinson's disease, tell your doctor promptly if you notice a change in the appearance or size of moles or other unusual skin changes. Ask your doctor if you should have regular skin exams.
If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip themissed dose. Take your next dose at the regular time. Do not double the dose to catch up.
Store at room temperature at 77 degrees F (25 degrees C) away from light and moisture. Brief storage between 59-86 degrees F (15-30 degrees C) is permitted. Do not store in the bathroom. Keep all medicines away from children and pets.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.Information last revised October 2018. Copyright(c) 2018 First Databank, Inc.
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