Nexium (esomeprazole) is intended for the treatment of conditions resulting from excessive amounts of stomach acid being produced. Nexium decreases the amount of acid produced in the stomach. Never take Nexium if you have an allergy to this medicine or any other medications before talking to your health care provider. If you already had an allergic reaction to some drug, taking it again is most likely to cause the same reaction, and you will be unable to get all the benefits of the treatment. Nexium is usually taken from 4-8 weeks in a row, after which the course of treatment may be repeated if needed. Taking Nexium for longer than recommended if not going to make your treatment more efficient and help you benefit from taking this medicine. Each dose should be taken with a full glass of water and it's important to avoid missing doses. The missed dose is supposed to be taken as son as you remember about it, unless it's time for the next dose. If an overdose of Nexium takes place, seek emergency medical help, especially if you get any of the following symptoms: headache, dry mouth, nausea, blurred vision, confusion, sweating, shortness of breath, flushing, and drowsiness.