Alendronic acid is a type of bisphosphonate medication utilized in the treatment of osteoporosis and Paget’s disease of the bone. The most commonly observed side effect of this drug is inflammation of the esophagus, which can lead to symptoms such as heartburn or difficulties in swallowing. Additional side effects may include headaches, abdominal discomfort and bloating, as well as episodes of diarrhea or constipation.