Fildena 50 (Sildenafil Citrate 50 mg) is not recommended in certain situations due to safety concerns or potential interactions. Here are the main cases when you should avoid taking Fildena 50: When Fildena 50 is NOT recommended: If you are allergic to Sildenafil or any ingredients in the tablet. If you are currently taking nitrates (such as nitroglycerin for chest pain) or nitric oxide donors — combining these can cause a dangerous drop in blood pressure. If you have serious heart conditions, such as: Recent heart attack or stroke (usually within the past 6 months) Severe heart failure or unstable angina Low blood pressure or uncontrolled high blood pressure If you have severe liver or kidney problems. If you have a rare inherited eye disease called retinitis pigmentosa (Sildenafil can worsen vision issues in these patients). If you are taking certain medications that can interact dangerously with Sildenafil, including: Some antibiotics (like erythromycin) Certain antifungals (like ketoconazole) HIV protease inhibitors Other PDE5 inhibitors (avoid mixing) If you have a history of prolonged or painful erections (priapism). If you are under 18 years old (safety and efficacy not established).