Flushing/warmth in the face and neck, headache, itching, burning, sweating, chills, or tingling may occur within 20 minutes to 4 hours of taking this medication. Flushing may persist for a few hours. These effects should improve or go away as your body adjusts to the medication. Stomach upset, heartburn, nausea, vomiting, and diarrhea may also 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. This is very important if you are also taking medication to lower your blood pressure.
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: severe dizziness/fainting, fast/irregular heartbeat, severe headache (migraine), unusual joint pain, swelling of legs/arms, vision problems, severe stomach/abdominal pain, black stools, easy bruising/bleeding, unexplained muscle pain/tenderness/weakness, persistent nausea/vomiting, change in the amount of urine, dark urine, vomit that looks like coffee grounds, yellowing eyes/skin.
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.