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 immediately if any of these unlikely but serious side effects occur: purplish-red blotchy spots on the skin, swelling of the ankles/feet, difficulty urinating, vision changes.
Tell your doctor immediately 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, including up to 1 year after starting the medication. 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.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.