Nexium comes with a lot of side effects. Some are common and some are less common. The most common are headaches, diarrhea, nausea, flatulence, decreased appetite, dry mouth, constipation, and abdominal pain. The less common side effects range from allergic reactions and dark urine all the way to muscle spasms and seizures. If anyone has any of these symptoms they should contact a doctor immediately. Along with side effects there are quite a few risks that come with Nexium as well. These risks include hip fracture, kidney damage, polyps, and pneumonia and clostridium difficile infection. Overdosing is also something that can happen when consuming Nexium. Results from overdosing are confusion, drowsiness, vision problems, nausea, sweating, headaches, dry mouth, and rapid heartbeats.