Lansoprazole 30-milligram capsules, marketed as Prevacid, may take up to four days to take effect, states Drugs.com. The typical adult dose for gastric ulcer is one capsule daily, 30 minutes before eating, for four to eight weeks. For erosive esophagitis, adults take one capsule daily for up to eight weeks.
Patients need to take lansoprazole exactly as prescribed by their doctors, notes Drugs.com. A patient taking a time-release capsule must swallow it whole, and not chew, break or crush it. A person taking an orally disintegrating tablet must allow it to dissolve in the mouth without chewing it and must not swallow it whole.
Lansoprazole is a drug known as a proton pump inhibitor. It decrease stomach acid production, and helps treat stomach and intestinal ulcers. Prevacid OTC is nonprescription lansoprazole.