Difference Between Prilosec and Nexium

Prilosec and Nexium are two drugs coming under the drug class category of proton pump inhibitors. Proton pumps are situated in mitochondrial membranes, which mean they are in all most all cells. The importance of these drugs is that they selectively inhibit proton pumps in the stomach lining. The mechanism of action is to selectively inhibit H+/K+ ATPase enzyme in gastric parietal cells. In the sense of organic chemistry, both these drugs are benzimidazoles containing substituted benzene ring and imidazole ring.


Prilosec is also known by the trade name Zegerid. The generic name of this drug is Omeprazole. It is a proton pump inhibitor. This drug is prescribed to treat complications related to excessive acid secretion in the stomach such as damage to esophagus and gastroesophageal reflux disease (GERD). This drug cannot render immediate relief from heartburns. The tablet should be taken 30 minutes before meals. The pill should be swallowed as a whole without chewing because it may damage the coating which is designed to protect the stomach. Granular suspension should be taken only with apple juice. Sometimes the granular suspension is delivered through nasogastric feeding tube.

There are a number of harmful effects of the drug. Animal studies have shown chronic usage may cause stomach cancers although it is not confirmed with humans up to the date. Tendency to increase bone fracture in hips, wrists, and spine is also found through clinical studies. Long term usage has shown to decrease the Vitamin B12 absorption and, therefore, cause B12 deficiency. Apart from all the harmful effects the drug also has various side effects associated. Uneven and fast heart rate, muscle weakness, diarrhea, coughing and choking, headache, and troubles in memory are some of the serious side effects. In addition weight change, stomach pain, insomnia is also experienced.

Prilosec should not be taken if one is allergic to the drug. It should not be taken while under medication of other benzimidazole drugs. If a person is taking HIV AIDS medicine, ampicillin, blood thinner, water pills, iron tablets, diabetes medicine it is important to seek medical advice before taking Prilosec


Nexium is also another proton pump inhibitor drug. The generic name of the drug is Esomeprazole. Both prilosec and Nexium have the same molecular formula; the difference stands where Nexium is the “S” enantiomer but Prilosec is actually a mixture of both “R” and “S” enantiomers. Enantiomers are actually the two stereo chemical forms of the same drug. They are like mirror images of each other. Most of the characteristics are similar for the two drugs. Nexium is not available without a prescription. Nexium shows an additional side effect of drying mouth apart from the mentioned side effects.

What is the difference between Prilosec and Nexium?

• Prilosec is a mixture of R and S enantiomers of the drug but Nexium contains only S enantiomer.

• Prilosec is available for use without prescription, but Nexium is not given without a prescription.

• Prilosec and Nexium have many similar side effects, and Nexium shows dry mouth as an additional side effect.