Medicine Name: Retense Capsule. Composition: Flupirtine (100mg). Side Effects: Fatigue Dizziness Nausea Dryness in mouth Tremors Heartburn Vomiting Abdominal pain Constipation Loss of appetite Depression Headache Abdominal discomfort Sleep disturbance Increased sweating Restlessness Nervousness Flatulence Diarrhea.