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U.S. Department of Health and Human Services


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Nexium (esomeprazole magnesium) for delayed-release oral suspension, delayed-release capsules and (esomeprazole sodium) for injection

Detailed View: Safety Labeling Changes Approved By FDA Center for Drug Evaluation and Research (CDER) – June 2011 


Summary View 


This information pertains to the risk of hypomagnesemia related to the use of proton pump inhibitors (PPIs) for at least three months, and in most cases after a year.


  • Hypomagnesemia, symptomatic and asymptomatic, has been reported rarely in patients treated with proton-pump inhibitors PPIs for at least three months, in most cases after a year of therapy. Serious adverse events include tetany, arrhythmias, and seizures. In most patients, treatment of hypomagnesemia required magnesium replacement and discontinuation of the proton pump inhibitors PPI.
  • For patients expected to be on prolonged treatment or who take PPIs with medications such as digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), health care professionals may consider monitoring magnesium levels prior to initiation of PPI treatment and periodically thereafter. 
  • information regarding interactions with diagnostic investigations for neuroendocrine tumors, and concomitant use with St. John’s Wort or rifampin


  • information regarding interactions with diagnostic investigations for neuroendocrine tumors, and concomitant use with tacrolimus, digoxin, and St. John’s Wort or rifampin


Postmarketing Experience

Metabolism and Nutritional Disorders:

  • hypomagnesemia


  • Advise patients to immediately report and seek care for any cardiovascular or neurological symptoms including palpitations, dizziness, as these may be signs of hypomagnesemia.


What should I tell my doctor before taking a proton pump inhibitor (PPI)?

Before you take a PPI, tell your doctor if you:

  • have been told that you have low magnesium levels in your blood
What are the possible side effects of a PPI?

Low magnesium levels in your body. This problem can be serious. Low magnesium can happen in some people who take a proton pump inhibitor medicine for at least 3 months. If low magnesium levels happen, it is usually after a year of treatment. You may or may not have symptoms of low magnesium. Tell your doctor right away if you have any of these symptoms of low magnesium levels:

  • seizures
  • dizziness
  • abnormal or fast heart beat, or skipped heartbeat
  • jitteriness
  • jerking movements or shaking (tremors)
  • muscle weakness
  • spasms of the hands and feet
  • cramps or muscle aches
  • spasm of the voice box
  • Your doctor may check the level of magnesium in your body before you start taking a PPI, or during treatment; or if you will be taking a PPI for a long period of time. 


“What Should I Tell my Doctor Before Taking Nexium”
  • addition of St. John’s Wort (Hypericum perforatum) and Rifampin to the medication list