Lansoprazole — what it is and who needs it

Lansoprazole is a proton pump inhibitor (PPI) that lowers stomach acid. You’ll see it sold as Prevacid and as generic lansoprazole. Doctors use it for acid reflux (GERD), stomach and duodenal ulcers, and conditions that cause too much stomach acid like Zollinger–Ellison syndrome. It’s also part of many H. pylori treatment plans paired with two antibiotics.

How to take lansoprazole

Take lansoprazole once a day, usually 15–30 mg for most adults. For best effect, swallow the capsule or tablet whole about 30–60 minutes before breakfast. Do not crush or chew delayed-release forms — that ruins how it works. If you miss a dose, take it as soon as you remember unless it’s almost time for the next dose. Don’t double up.

Over-the-counter options are available at lower doses. Prescription doses and treatment length vary — some problems need 2–8 weeks, while others may require longer. If you and your doctor plan long-term use, ask about the lowest effective dose and regular check-ins.

Side effects, risks, and interactions

Common side effects are mild: headache, stomach pain, nausea, diarrhea, or constipation. Serious problems are less common but worth watching for. Long-term PPI use has been linked to lower magnesium and vitamin B12 levels, a small increase in bone fracture risk, and a higher chance of certain infections like C. difficile. Your doctor may check blood levels or bone health if you’re on lansoprazole for months or years.

Lansoprazole can change how other drugs work. It can reduce absorption of medicines that need stomach acid (for example, ketoconazole, atazanavir, and iron supplements). It may also affect clopidogrel’s activation — talk with your doctor or pharmacist if you take blood thinners. Always tell your provider about all prescription drugs, OTC meds, and supplements you use.

Stopping lansoprazole suddenly can cause rebound acid — more heartburn than before. If you want to stop, ask your doctor about tapering the dose or temporary alternatives like H2 blockers to ease the switch.

Seek medical help right away for warning signs: trouble swallowing, persistent vomiting, unexplained weight loss, black or bloody stools, or severe abdominal pain. These may be signs of a serious condition that needs prompt care.

If you’re pregnant, breastfeeding, elderly, or have liver disease, check with your doctor before starting lansoprazole. They’ll weigh the benefits and risks and may suggest monitoring or a different option.

Want a quick checklist? Take the lowest effective dose, take it before breakfast, watch for long-term risks, avoid mixing with certain drugs without advice, and see your doctor for any worrying symptoms.