What are side effects of the drug alendronate/fosamax for osteoporosis..?

Mostly heartburn: Alendronate is generally well tolerated. Reflux is the most common side effect. It can also cause bone pain, esophageal ulcers or narrowing. The generic alendronate may have more GI side effects because it is not coated. This concern has not been answered adequately enough in large studies. It is very important to discuss these issues with your physician.

Sore swalllowing: Fosamax (alendronate) is a powerful osteoporosis treatment, but can cause irritation of the swallowing tube rarely. People with serious reflux esophagus problems should consider intravenous or injectibel medication.