Nizatidine is prescribed for the treatment of duodenal ulcers and non-cancerous stomach ulcers. Full-dose therapy for these problems lasts no longer than 8 weeks. However, your doctor may prescribe Nizatidine at a reduced dosage after a duodenal ulcer has healed. The drug is also prescribed for the heartburn and the inflammation that result when acid stomach contents flow backward into the esophagus. Nizatidine belongs to a class of drugs known as histamine H2 blockers.