See also Warning section.Dizziness, lightheadedness, drowsiness, nausea, vomiting, tiredness, excess saliva/drooling, blurred vision, weight gain, constipation, headache, and trouble sleeping may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.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 you have any serious side effects, including: fainting, mental/mood changes (such as increased anxiety, depression, suicidal thoughts), trouble swallowing, restlessness (especially in the legs), shaking (tremor), muscle spasm, mask-like expression of the face, seizures, signs of infection (such as fever, persistent sore throat).This medication may infrequently make your blood sugar level rise, which can cause or worsen diabetes. Rarely, very serious conditions such as diabetic coma may occur. Tell your doctor immediately if you develop symptoms of high blood sugar, such as increased thirst and urination. If you already have diabetes, be sure to check your blood sugars regularly. Your doctor may need to adjust your diabetes medication, exercise program, or diet.This medication may rarely cause a condition called tardive dyskinesia. In some cases, this condition may be permanent. Tell your doctor right away if you develop any unusual uncontrolled movements (especially of the face, mouth, tongue, arms, or legs).This medication may rarely cause a very serious condition called neuroleptic malignant syndrome (NMS). Get medical help right away if you have any of the following symptoms: fever, muscle stiffness/pain/tenderness/weakness, severe tiredness, severe confusion, sweating, fast/irregular heartbeat, dark urine, change in the amount of urine.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: 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.