Although both drugs inhibit secretion of stomach acids, Prilosec and Zantac belong to the different class of drugs, and moreover, their mechanism of action is also not the same. Prilosec (omeprazole) lasts longer (up to 72 hours) than other classes of acid reducers (like Zantac, Pepcid, or Tums). Only take once or twice daily. Simply put, Zantac and Prilosec work differently even though they have the same goals. Zantac is classified as an H2 blocker, which decreases acid production in the stomach by blocking the receptors that trigger it. I took Omeprazole (generic for Prilosec) for 12 years when I found that I was having some horrible side affects such as Urinary Tract Infections, Sinus Infections, bone pain, shortness of breath, nausea in the morning, etc. Prilosec and Zantac come in tablet, capsule, and liquid forms that you take by mouth. For either drug, the typical length of treatment is two to eight weeks, depending on what you’re treating. Zantac (ranitidine hydrochloride) and Prilosec (omeprazole) are used for the treatment of conditions such as heartburn, ulcers, gastroesophageal reflux disease (GERD), erosive esophagitis, and Zollinger-Ellison syndrome, which are all caused by stomach acid. I agree with Marvel, but a quick call to your doc (in the morning probably) wil do the trick. As she said maybe lose the zantac & try ust the Prilosec & see how you react. Prilosec (omeprazole) and Zantac (ranitidine) are for the treatment of conditions such as ulcers and gastroesophageal reflux disease (GERD) caused by stomach acid. Both drugs work in different ways to reduce stomach acid; one is a proton-pump inhibitor and the other is an H2 blocker. You should know: The answer above provides general health information that is not intended to replace medical advice or treatment recommendations from a qualified healthcare professional. Form. Prilosec is available as 2.5 mg suspension, 10 mg suspension, and 10, 20 or 40 mg delayed-release capsules. Zantac is available in 150 and 300 mg tablets, effervescent tablets, effervescent granules and a syrup.