Sildenafil 100 mg may cause side effects, though not everyone experiences them. Common side effects include headaches, flushing, upset stomach, nasal congestion, and dizziness. Some individuals may also experience visual disturbances, such as a blue tint to vision or increased sensitivity to light. In rare cases, more serious side effects may occur, such as priapism (prolonged erection), sudden vision loss, or hearing loss. If you experience chest pain, irregular heartbeat, or an erection lasting more than 4 hours, seek immediate medical attention. Always consult with your healthcare provider before using Sildenafil to understand the risks and ensure it's safe for you.