Fosamax is a prescription drug used to treat osteoporosis and Paget’s disease of the bone in adults. Its main ingredient is alendronate sodium. Common side effects of Fosamax include stomach discomfort, acid reflux, and joint or muscle pain. To minimize these side effects, it is recommended to take Fosamax on an empty stomach with a full glass of water and remain upright for at least 30 minutes after taking it. If you experience severe side effects such as loose teeth or severe chest pain, contact your doctor immediately. For long-term Fosamax users, regular dental and bone health check-ups are crucial. Overall, following your doctor's advice and regular check-ups can effectively manage the side effects of Fosamax.