Prevacid (lansoprazole) is a proton pump inhibitor used to treat conditions caused by excess stomach acid, including acid reflux, stomach ulcers, and esophageal damage. It’s available both over the counter for frequent heartburn and by prescription for more serious digestive conditions. Here’s what it treats, how it works, and what to know if you’re taking it.
How Prevacid Reduces Stomach Acid
Prevacid works by shutting down the tiny acid-producing pumps inside the cells lining your stomach. These pumps, called proton pumps, are what generate hydrochloric acid every time you eat. Lansoprazole enters these cells, gets activated by the acidic environment, and permanently disables the pumps it reaches. Your stomach has to build entirely new pumps to resume normal acid production, which is why the effect lasts well beyond the time the drug is in your bloodstream.
This makes Prevacid fundamentally different from antacids like Tums, which simply neutralize acid already in your stomach, or H2 blockers like famotidine, which partially reduce acid output. Proton pump inhibitors like Prevacid suppress acid production more completely and for a longer duration, which is why they’re the go-to treatment when the goal is healing damaged tissue rather than just relieving occasional heartburn.
FDA-Approved Uses
Prevacid is approved for a wide range of acid-related conditions in adults:
- GERD (acid reflux disease): Both the symptoms (chronic heartburn, regurgitation) and the tissue damage it can cause.
- Erosive esophagitis: Healing and long-term maintenance of damage to the esophagus caused by stomach acid washing upward repeatedly.
- Duodenal ulcers: Treatment of active ulcers in the upper part of the small intestine, plus maintenance therapy to keep healed ulcers from returning.
- Gastric ulcers: Treatment of active stomach ulcers, including those caused by long-term use of NSAIDs like ibuprofen or naproxen.
- NSAID ulcer prevention: Reducing the risk of stomach ulcers in people who need to keep taking anti-inflammatory painkillers.
- H. pylori eradication: Used alongside antibiotics to clear the bacterial infection that causes many ulcers.
- Zollinger-Ellison syndrome: A rare condition where tumors cause the stomach to produce dangerously high levels of acid.
GERD and Erosive Esophagitis
The most common reason people take Prevacid is gastroesophageal reflux disease. When the valve between your esophagus and stomach doesn’t close properly, acid repeatedly washes upward and irritates the esophageal lining. Over time, this can progress from simple heartburn to erosive esophagitis, where the tissue develops visible sores and inflammation.
Clinical studies show Prevacid heals erosive esophagitis in roughly 62% to 86% of patients within four weeks, depending on severity. By eight weeks, healing rates climb to 75% to 93%. Most treatment courses run four to eight weeks. For people whose esophagitis keeps coming back, Prevacid is also approved for long-term maintenance to prevent recurrence.
Ulcers and NSAID Protection
Stomach and duodenal ulcers are open sores in the digestive lining, typically caused by either H. pylori bacteria or regular use of painkillers like ibuprofen, aspirin, or naproxen. Prevacid treats active ulcers by dialing acid production down low enough for the tissue to repair itself. Duodenal ulcers generally heal within four weeks, and gastric ulcers within eight.
If you take NSAIDs regularly for arthritis or other chronic pain, Prevacid can also be prescribed preventively to reduce the risk of developing stomach ulcers in the first place. This is particularly relevant for older adults or anyone with a history of ulcers who can’t stop their anti-inflammatory medication.
H. pylori Infection
H. pylori is a bacterium that burrows into the stomach lining and is responsible for the majority of duodenal ulcers. Prevacid alone won’t clear the infection. Instead, it’s used as part of “triple therapy,” a 10- to 14-day regimen that combines lansoprazole with two antibiotics. Prevacid’s role in this combination is to suppress acid enough that the antibiotics can work effectively in the stomach environment. Once the bacteria are eradicated, the risk of the ulcer returning drops significantly.
Rare Hypersecretory Conditions
Zollinger-Ellison syndrome is a rare condition in which tumors (usually in the pancreas or small intestine) trigger the stomach to produce massive amounts of acid, far beyond normal levels. People with this condition often need much higher doses of Prevacid and may stay on the medication for years. Some patients have been treated continuously for over four years. Unlike the standard four-to-eight-week courses used for ulcers or GERD, treatment here continues as long as clinically necessary.
Use in Children
Prevacid is approved for children ages 1 through 17 for short-term treatment of GERD symptoms and erosive esophagitis. Treatment courses typically last up to 8 weeks for teens and up to 12 weeks for younger children (ages 1 to 11). It is not approved for infants under one year old. A clinical trial in babies aged one month to under one year found it was no more effective than a placebo for reflux symptoms in that age group.
OTC vs. Prescription Versions
Prevacid 24HR is the over-the-counter version, sold in 15 mg capsules and intended for frequent heartburn (two or more days per week). It’s meant for 14-day courses, not ongoing daily use. The prescription version comes in both 15 mg and 30 mg strengths and covers the full range of approved conditions, from ulcers to erosive esophagitis to Zollinger-Ellison syndrome. If your symptoms go beyond occasional heartburn or persist after a 14-day OTC course, the prescription version allows your doctor to tailor the dose and duration to your specific condition.
How to Take It
Timing matters with Prevacid. It should be taken before eating, ideally 30 minutes before a meal. Taking it after food cuts absorption by 50% to 70%, which can make the medication significantly less effective. This is because the drug needs to reach your stomach’s acid-producing cells while they’re gearing up to respond to a meal, not after they’ve already done their work.
The capsules are delayed-release, meaning they’re designed to pass through the stomach intact and dissolve in the small intestine, where the drug gets absorbed. Don’t crush or chew them. If you have trouble swallowing capsules, the SoluTab version dissolves on the tongue.
Side Effects and Long-Term Considerations
Short-term use of Prevacid is generally well tolerated. The most common side effects are mild: headache, nausea, diarrhea, and stomach pain. These usually resolve on their own.
Long-term use (a year or more) raises some additional concerns. Stomach acid plays a role in absorbing certain nutrients, so chronically suppressing it can lead to deficiencies. Vitamin B-12 is the best-studied example: daily use of proton pump inhibitors for a year or more increases the risk of low B-12 levels, since the body needs acid to extract this vitamin from food. Magnesium and calcium absorption may also be affected over time, which is one reason doctors periodically reassess whether ongoing use is still necessary.
Prevacid can also interact with other medications. If you take methotrexate for conditions like rheumatoid arthritis or psoriasis, lansoprazole may increase methotrexate levels in your blood, raising the risk of side effects. Let your prescriber know about all medications you’re taking, including over-the-counter drugs and supplements.