Fildena CT 50 contains sildenafil citrate, and muscle aches (myalgia) can occur as an occasional side effect. The reason is not fully understood, but possible explanations include: Blood vessel effects: Sildenafil increases levels of a molecule called cGMP, which relaxes blood vessels. These changes may sometimes contribute to sensations of muscle discomfort or aching. Mild systemic effects: Because sildenafil circulates throughout the body, some people experience body aches, back pain, or muscle soreness along with other effects such as headache or flushing. Individual sensitivity: Some people metabolize the medicine differently, making side effects more noticeable. What may help: Stay well hydrated. Avoid heavy alcohol use around the time you take it. Avoid intense exercise immediately before or after taking it if you notice a pattern of soreness. Discuss dose adjustment with a healthcare professional if aches are frequent or bothersome. Seek medical advice promptly if muscle pain is severe, unusual, accompanied by weakness, dark urine, chest pain, or other concerning symptoms. If you tell me when the muscle aches start (same day, next day, or after several hours), where they occur, and how long they last, I can help assess whether it fits a typical sildenafil side effect pattern.