Happi 20mg Capsule ER contains Rabeprazole 20mg, a proton pump inhibitor (PPI) used to reduce gastric acid secretion in the treatment of various acid-related gastrointestinal disorders. Rabeprazole acts by irreversibly inhibiting the H+/K+ ATPase enzyme system located on the gastric parietal cells, thereby suppressing the final step of acid production. This extended-release formulation ensures a prolonged therapeutic effect, providing sustained acid suppression over 24 hours. Happi 20mg Capsule ER is indicated for the management of gastroesophageal reflux disease (GERD), erosive esophagitis, Zollinger-Ellison syndrome, and peptic ulcer disease, including Helicobacter pylori eradication regimens when combined with appropriate antibiotics. The medication is generally well tolerated; common adverse effects may include headache, diarrhea, nausea, abdominal pain, and dizziness. It is contraindicated in patients with known hypersensitivity to Rabeprazole or other PPIs. Caution is advised in patients with severe hepatic impairment and those on concomitant medications metabolized by cytochrome P450 enzymes due to potential drug interactions. Patients should adhere to prescribed dosing schedules and consult healthcare providers before initiating or discontinuing therapy. Regular monitoring may be necessary for long-term use to assess therapeutic efficacy and detect potential adverse effects.