Alendronate is generally well tolerated and adverse effects are usually mild and do not require discontinuance of the drug.
The most common adverse effects seen in clinical trials include abdominal pain, nausea, dyspepsia, constipation, diarrhea, flatulence, acid regurgitation, vomiting, dysphagia, abdominal distention, gastritis, gastric ulcer, gastroesophageal reflux disease (GERD), melena, esophagitis, esophageal erosions, esophageal ulcers, and taste perversion. Rarely, esophageal stricture or perforation, oropharyngeal ulceration, and gastric or duodenal ulcers (some severe and with complications).
Anastomotic ulcer with mild hemorrhage has been reported with concomitant aspirin use.
Esophageal cancer has been reported during postmarketing experience in patients receiving alendronate or other bisphosphonates. The most common site of cancer was the distal esophagus, with gastric involvement in some patients.
Vertigo, headache, dysgeusia and dizziness.
Musculoskeletal/Connective Tissue and Bone Effects:
Musculoskeletal (bone, muscle or joint) pain which is occasionally severe but rarely incapacitating, muscle cramp, joint swelling, low-energy femoral shaft fracture, transient symptoms of myalgia, asthenia and malaise.
There have been rare reports of ONJ generally associated with tooth extraction and/or local infection, often with delayed healing.
Hypersensitivity reactions including urticaria and rarely, angioedema. Rash (occasionally with photosensitivity), alopecia and erythema have been rarely reported. Pruritus and rarely, severe skin reactions including Stevens-Johnson syndrome and toxic epidermal necrosis have also been reported.
Fever typically associated with initiation of treatment, and asymptomatic, mild, and transient decreases in serum calcium and phosphate. Rarely, reports of severe symptomatic hypocalcemia have occurred in patients with predisposing factors such as hypoparathyroidism, Vitamin D deficiency and calcium malabsorption.
Uveitis (rarely), scleritis or episcleritis.
Asthenia and peripheral edema.