Tadalafil and Viagra (Sildenafil) are both effective treatments for erectile dysfunction, but they work differently. Viagra typically starts working within 30 to 60 minutes and lasts about 4 to 6 hours. Tadalafil, found in medications like Vidalista Black 80, takes effect in a similar timeframe but can last up to 36 hours, offering a longer duration for sexual activity. In terms of strength, both drugs are effective, but individual responses may vary. Tadalafil is considered more convenient due to its extended duration, while Viagra may work slightly faster for some men. Neither is necessarily "stronger" ; the best choice depends on personal preference, lifestyle, and medical advice. Always consult a healthcare provider to determine which medication suits your needs best.