Do not take a Fosamax tablets if you: Cannot sit upright or stand for at least 30 minutes because it can cause serious problems in the stomach or esophagus. You will need to stay upright for at least 30 minutes after taking this medication., Are allergic to alendronate, have low levels of calcium in your blood (hypocalcemia), or a problem with the movement of muscles in your esophagus. To make sure you can safely take Fosamax, tell your doctor if you have any of the following: Trouble swallowing, Vitamin D deficiency, Dental problem, Kidney disease, Ulcer or other problem in your stomach or esophagus Other important information patients should know about before they take Fosamax is some patients who are using similar medications have developed bone loss in the jaw (osteonecrosis). Symptoms may include jaw pain, swelling, numbness, loose teeth, gum infection, or slow healing after injury or surgery involving the gums. Talk with your doctor about the risks and benefits of using Fosamax.