The drugs Prevacid and Prilosec have a different active ingredient, a different propensity for causing allergic reactions, and may differ in their ability to treat certain conditions, according to Diffen. The active ingredient in Prevacid is lansoprazole, while the active ingredient in Prilosec is omeprazole. Prevacid has been found to be more effective at treating gastroesophageal reflux disease, or GERD. While both drugs can cause an allergic reaction, Prilosec is more likely to do so.
Prevacid and Prilosec are both medications that are used to treat the production of excessive acid in the stomach and are used in the treatment of ulcers and GERD, notes Diffen. They operate by inhibiting the stomach's acid-producing proton pumps. Both medications are available over-the-counter or by prescription. Prevacid and Prilosec have similar side effects, including headache, nausea and dizziness. Both drugs become active in the body within 24 hours after consumption but may take between one and four days to achieve efficacy. When patients stop taking Prevacid or Prilosec, they are likely to experience withdrawal in the form of increased acid production.
Prevacid and Prilosec are both ingested orally and are typically taken directly before a meal, states Diffen. Both drugs may have negative interactions with antibiotics, anticoagulants and iron supplements. Prilosec may also interact with benzodiazepines.