See also the Warning section. Dizziness, lightheadedness, nausea, vomiting, tiredness, excess saliva/drooling, blurred vision, weight gain, drowsiness and constipation 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: fast/pounding heartbeat, fainting, mental/mood changes (e.g., increased anxiety, depression, suicidal thoughts), weakness, feelings of restlessness, mask-like facial expression, shakiness (tremors), muscle spasm/stiffness, trouble swallowing, swelling of the ankles/feet. Tell your doctor immediately if any of these rare but very serious side effects occur: seizures, signs of infection (such as fever, persistent sore throat). This drug may rarely cause a condition known as tardive dyskinesia. In some cases, this condition may be permanent. Tell your doctor immediately if you develop any unusual uncontrolled movements (especially of the face, mouth, tongue, arms or legs). This drug may infrequently cause a serious (rarely fatal) nervous system disorder (neuroleptic malignant syndrome). Seek immediate medical attention if you notice any of the following rare but very serious side effects: confusion, fever, fast heartbeat, muscle stiffness, increased sweating, change in the amount of urine. A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. 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.