sildenafil 150mg typically lasts 4 to 6 hours, but its effects can vary depending on factors like metabolism, age, and overall health. A 150mg dose is higher than the standard 50mg or 100mg, potentially leading to longer-lasting effects. Some users may experience benefits for up to 8 hours, though peak effectiveness occurs within the first 2 to 3 hours after ingestion. However, a higher dose also increases the risk of side effects like headaches, dizziness, and flushing. It is crucial to follow medical advice before taking such a dose, as 150mg is not a standard prescription strength for Viagra.