Nausea, vomiting, constipation, dry mouth, flushing, sweating, lightheadedness, dizziness, and drowsiness may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.To prevent constipation, maintain a diet adequate in fiber, drink plenty of water, and exercise. If you become constipated while using this drug, consult your pharmacist for help in selecting a laxative (e.g., stimulant-type with stool softener).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: slow/irregular/fast heartbeat, mental/mood changes (e.g., confusion, hallucinations, nervousness), numbness, shakiness (tremors), severe stomach/abdominal pain, trouble urinating, change in the amount of urine.Get medical help right away if you have any very serious side effects, including: slow/shallow breathing, fainting, seizures.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.