Omeprazole injection is indicated for the short-term treatment of gastroesophageal reflux disease (GERD) and erosive esophagitis, contraindicated in patients with known hypersensitivity to omeprazole or any component of the formulation, may cause side effects such as headache, nausea, and diarrhea, and can interact with drugs like clopidogrel and certain antifungals due to its effect on cytochrome P450 enzymes.