Side effects of generic Amantadine drug include blurred vision, nausea, stomach upset, drowsiness, dizziness, headache, dry mouth, constipation, nervousness, trouble sleeping, purplish-red blotchy spots on the skin, swelling of the ankles/feet, difficulty urinating, vision changes, shortness of breath, mental/mood changes (such as depression, suicidal thoughts/attempts, compulsive behavior including urge to gamble), muscle stiffness, uncontrolled muscle movements, unusual sweating, fast heartbeat, unexplained fever, seizures. Symptoms of a severe allergic response may include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.