Nexium (esomeprazole) is a medicine intended for the treatment of symptoms of gastroesophageal reflux disease. It works by reducing the amount of stomach acid produced. You are not supposed to take this medicine if you have a history of an allergic reaction to its active ingredient - esomeprazole. If you have liver disease of heart disease, your dose may need to be adjusted - so make sure you talk to your health care provider about that. It's recommended to take this medicine regularly and make sure you never exceed the dose prescribed. Although you are not expected to get any life-threatening symptoms after taking too much of Nexium, your local emergency center is supposed to be contacted anyway if you happened to overdose. Certain side effects are possible and they are unlikely to get too bothersome for you to handle. The following mild side effects are possible: nausea, gas, stomach pain, headache, dry mouth, diarrhea, and constipation, although you may develop some other ones that are not on the list. Do not combine Nexium with other medications without your doctor's consent, especially any of the following ones: iron, digoxin, blood thinners, diazepam, HIV or AIDS medications, ketoconazole, and clopidogrel.