Stomach pain, constipation, diarrhea, gas, or nausea may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor 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: jaw/ear pain, increased or severe bone/joint/muscle pain, new or unusual hip/thigh/groin pain, swelling of joints/hands/ankles/feet, black/tarry stools, vomit that looks like coffee grounds.This medication may rarely cause serious irritation and ulcers of the esophagus. If you notice any of the following unlikely but very serious side effects, stop taking alendronate and talk to your doctor or pharmacist right away: new or worsening heartburn, chest pain, pain or difficulty when swallowing.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), 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 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.