Tadalafil, the active ingredient in Tadarise 2.5 mg, typically starts working within 30 minutes to an hour after ingestion. However, the onset of action may vary from person to person based on factors such as metabolism and individual response. Before starting Tadarise 2.5 mg, it’s important to inform your healthcare provider about any other medications, supplements, or medical conditions you have. Tadalafil can interact with certain medications, especially nitrates and alpha-blockers.