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Difference between Prilosec and Nexium

Prilosec and Nexium


Prilosec and Nexium both belong to a group of drugs called as Proton Pump Inhibitors (PPIs). They are used for the treatment of dyspepsia or what is commonly termed as hyperacidity or indigestion. Although they are chemically similar, there are important subtle differences between the two medications that one must be aware about.


Prilosec and Nexium are both approved for nearly the same conditions. However, Prilosec is approved for use in children even as young as two years old, whereas, Nexium is approved only for adults. Prilosec is more affordable than Nexium.


Prilosec contains the drug ‘omeprazole’ and Nexium contains ‘esomeprazole magnesium’. Both are Proton Pump Inhibitors (PPI). Proton Pump Inhibitors work by lowering the amount of acid produced in the stomach.

Nexium and Prilosec contain very similar molecules but the minor differences in action make Nexium unfit for use in children.

Prilosec was available first and Nexium is just a recent discovery. Prilosec is a mixture of R and S enantiomers of omeprazole whereas Nexium contains just the S enantiomer of omeprazole. To make this easier, let us understand what enantiomers are. Enantiomers are forms of molecules that are almost exactly the same, but are “opposites” in polarity. A simple example would be to think of your right and left hands as enantiomers. Although they are very similar to each other, they are opposites.

Differences in indications:

    • Nexium and Prilosec are prescribed for treating duodenal ulcers which are caused due to Helicobacter Pylori.


    • Prilosec is also prescribed for duodenal ulcers caused due to other reasons apart from Helicobacter Pylori whereas Nexium is not.


    • Nexium and Prilosec are approved for treating non-cancerous or benign gastric ulcers. It is important to note that, Nexium is prescribed to treat gastric ulcers which are only produced due to non-steroidal anti-inflammatory drugs (NSAIDs). However, Prilosec is used to treat all kinds of gastric ulcers.


    • Prilosec has also been approved for healing hyper-secretory problems such as Zollinger-Elison Syndrome while Nexium is not.


    • Nexium and Prilosec have both been licensed for treating Gastro-oesophageal reflux disease (GORD) and esophagitis caused because of GORD.


    • Nexium is less affordable as compared to Prilosec, as it is not sold in generic form.


  • Prilosec can be procured without a prescription whereas; Nexium can be obtained only by prescription.


Prilosec and Nexium, both are Proton Pump Inhibitors (PPI) and are commonly used to treat acidity related disorders by lowering the amount of acid in the stomach. Both are used for treating duodenal and gastric ulcers. However, Prilosec is used for treating gastric ulcers from various causes, whereas Nexium is used to treat gastric ulcers caused due to Helicobacter Pylori. Prilosec has got more approval as a Proton Pump Inhibitor compared to Nexium. Prilosec can be purchased over-the-counter without a prescription, but Nexium needs a prescription. It is always safe to consult a physician before consuming either of these mentioned drugs for acidity related complaints. Both drugs have side-effects which must be considered before taking them.

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  1. Enantiomers are molecules that have a chiral center – a center that is a mirror image- not opposite in polarity. At the pH of the stomach the enantiomers should racemize, which means that Nexium will be no more effective than the same dose of Prilosec.

  2. Nexiun is now available OTC. Is this an old article?

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