Sildenafil 100mg may cause some mild to moderate side effects, especially when taken without proper guidance. Common effects include headache, dizziness, flushing, upset stomach, nasal congestion, and temporary vision changes. In some cases, users may also experience muscle pain or sensitivity to light. These effects are usually temporary and improve as the medicine leaves the body. Cenforce 100mg contains sildenafil citrate and may produce similar reactions if taken in high amounts or mixed with alcohol. To reduce risks, it is important to follow the recommended dosage and consult a healthcare professional before regular use for better safety and effectiveness.