Zhewitra 40 mg (vardenafil) with Forzest 20 mg (tadalafil) for duration, Forzest/tadalafil lasts considerably longer. Medicine Active ingredient Typical duration Zhewitra 40 mg Vardenafil Several hours; half-life ~4–5 hours Forzest 20 mg Tadalafil Erectile-function benefit can last up to 36 hours Vardenafil's usual maximum recommended dose for ED is 20 mg once daily—so Zhewitra 40 mg is above the standard Zhewitra 40 mg maximum. Tadalafil 20 mg, on the other hand, is an approved as-needed ED dose and can remain effective for up to 36 hours. So, for longer-lasting effect: tadalafil 20 mg generally wins. That doesn't mean a stronger dose gives better or longer sex; it mainly increases exposure and potentially side effects. Also, don't take Zhewitra and Forzest together or combine either with another PDE-5 inhibitor. If you're considering 40 mg Zhewitra specifically, I'd recommend checking with a doctor/pharmacist first because of the dose. If you tell me your age and whether your goal is longer erection, delaying ejaculation, or treating difficulty getting/keeping an erection, I can compare the options more specifically.