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Digestive Disorders



Brand Names: Prevacid, Prevpac
Drug Class: Antacid/proton pump inhibitor
Available in: Delayed-release capsules
Available OTC? No
As Generic? No

Side Effects

Serious: No serious side effects are associated with the use of this medication.

Common: Diarrhea, itching or rash, headache, dizziness.

Less Common: Abdominal or stomach pain, nausea, increase or decrease in appetite, anxiety, flu-like symptoms, constipation, coughing, mental depression, muscle pain.

Principal Uses

To treat stomach and duodenal (intestinal) ulcers, gastroesophageal reflux disease (chronic heartburn caused by the backwash of stomach acid into the esophagus), and conditions that cause increased stomach acid secretion, such as Zollinger-Ellison syndrome. To treat and prevent nonsteroidal anti-inflammatory drug (NSAID)-associated stomach ulcers. Lansoprazole is also prescribed in conjunction with the antibiotics amoxicillin and clarithromycin to eradicate the bacterium H. pylori and thus prevent the recurrence of duodenal ulcers caused by this bacterium.

How the Drug Works

Lansoprazole blocks the action of a specific enzyme in the cells that line the stomach, thus decreasing the production of stomach acid. Reduction of stomach acid creates a more favorable environment for the eradication of H. pylori and promotes the healing of ulcers.


Prevacid— To treat duodenal ulcers: Initial dose is 15 mg once a day; it may later be increased. To treat gastroesophageal reflux disease: 15 mg once a day for up to 8 weeks. To treat NSAID-associated stomach ulcers: 30 mg once a day for 8 weeks. To reduce the risk of NSAID-associated stomach ulcer: 15 mg once a day for up to 12 weeks. To treat other conditions: Initial dose is 60 mg once a day; it may be increased. Treatment usually runs 4 to 8 weeks. A second course of treatment may be necessary. For Zollinger-Ellison syndrome: Initial dose is 60 mg once a day; it may be increased. Prevpac— To prevent duodenal ulcers: 30 mg lansoprazole, 1 gram amoxicillin, and 500 mg clarithromycin every 12 hours for 14 days.

Onset of Effect

1 to 3 hours.

Duration of Action

More than 24 hours.

Dietary Advice

The drug is best taken 30 minutes or more before a meal, preferably breakfast.


Store in a tightly sealed container away from heat, moisture, and direct light.

If You Miss a Dose

Take it as soon as you remember. However, if it is near the time for the next dose, skip the missed dose and resume your regular dosage schedule. Do not double the next dose.

Stopping the Drug

Take as prescribed for the full treatment period, even if your symptoms improve before the scheduled end of therapy.

Prolonged Use

Lansoprazole should not be used indefinitely as maintenance therapy for duodenal ulcer or esophagitis; other treatments are advised.


Over 60: No special problems are expected.

Driving and Hazardous Work: Avoid such activities until you determine how the drug affects you.

Alcohol: Avoid alcohol throughout the duration of therapy with this drug.

Pregnancy: Adequate human studies have not been done. Before taking lansoprazole, tell your doctor if you are pregnant or plan to become pregnant.

Breast Feeding: Lansoprazole may pass into breast milk; consult your doctor for advice.

Infants and Children: Use and dose for anyone under 18 should be determined by your doctor or pediatrician.

Special Concerns

Tell any doctor or dentist whom you see for treatment that you are taking lansoprazole. Do not chew the capsules. If you have trouble swallowing them, you may open them and sprinkle the contents on one tablespoon of applesauce, cottage cheese, yogurt, or similar food. If your doctor directs, you may take an antacid along with lansoprazole.


Symptoms: No cases of overdose have been reported.

What to Do: An overdose is unlikely to be life-threatening. However, if someone takes a much larger dose than prescribed, seek medical attention immediately.

Drug Interactions

Consult your doctor for specific advice if you are taking ampicillin, sucralfate, iron salts or supplements, cyclosporine, diazepam, disulfiram, ketoconazole, phenytoin, or theophylline.

Food Interactions

No significant food interactions have been reported.

Disease Interactions

Caution is advised when taking lansoprazole. Consult your doctor if you have liver disease, since it may increase the risk of side effects.


From The Johns Hopkins Consumer Guide to Drugs. You can order this book now on our secure server.


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Digestive Disorders

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