Lansoprazole works by blocking acid production in the stomach. This medication is known as a proton pump inhibitor (PPI). It is used to treat acid-related stomach and throat (esophagus) problems (e.g., acid reflux or GERD, ulcers, erosive esophagitis, Zollinger-Ellison syndrome). Decreasing excess stomach acid can help relieve symptoms such as heartburn, difficulty swallowing, persistent cough, and trouble sleeping. It can also prevent serious acid damage to your digestive system (e.g., ulcers, cancer of the esophagus). Lansoprazole may also be used to treat ulcers due to the long-term use of certain drugs for pain or swelling (NSAIDs-nonsteroidal anti-inflammatory drugs). In addition, this medication may be used in combination with antibiotics to treat certain types of ulcers caused by bacterial infection. How to use Prevacid Oral Take this medication by mouth, usually once daily, before a meal; or as directed by your doctor. Place the tablet on your tongue. It will break apart in less than 1 minute, with or without water. Swallow the tablet bits. Do not swallow the tablet whole; do not crush or chew it. Antacids may be taken along with this medication, if needed. The dosage and length of treatment is based on your medical condition and response to therapy. Use this medication regularly in order to get the most benefit from it. To help you remember, use it at the same time each day. Continue to take this medication for the prescribed length of treatment even if you are feeling better. Inform your doctor if your condition persists or worsens.