Fildena CT 50 mg contains Sildenafil Citrate, a medicine used for erectile dysfunction. It can interact with other medicines because it affects blood vessels, blood pressure, and certain liver enzymes involved in drug metabolism. 1) It lowers blood pressure Sildenafil relaxes blood vessels and increases blood flow. If taken with other drugs that also lower blood pressure, the effect can become too strong, leading to dizziness, fainting, or dangerously low blood pressure. Common interacting drugs include: Nitrates (e.g., nitroglycerin for chest pain) Some alpha-blockers (used for prostate enlargement or high BP) 2) It affects the nitric oxide pathway Fildena enhances the nitric oxide–cGMP pathway, which is also influenced by certain heart medications. Combining similar-acting drugs can cause excessive vasodilation. 3) It is broken down by liver enzymes (CYP3A4) Sildenafil is metabolized mainly by the liver enzyme CYP3A4. Some medicines can increase or decrease its levels in the blood: Increase Sildenafil levels (more side effects): Ketoconazole, itraconazole (antifungals) Ritonavir (HIV medicine) Erythromycin, clarithromycin (antibiotics)  .