Penegra 100 mg contains sildenafil citrate, a PDE5 inhibitor used to treat erectile dysfunction. While effective, it is not safe for everyone. Certain people should stop or avoid using Penegra 100 mg: People taking nitrate medications: Those using nitroglycerin, isosorbide dinitrate, or other nitrates for chest pain should never take Penegra, as the combination can cause a dangerous drop in blood pressure. Severe heart conditions: Individuals with recent heart attack, stroke, or unstable angina should avoid it. Severe heart failure or uncontrolled arrhythmias can make using Penegra risky. Low or uncontrolled high blood pressure: Sildenafil can affect blood pressure, so those with extreme blood Penegra 100 mg values should not use it without a doctor’s guidance. Severe liver or kidney problems: Impaired organ function can affect how the drug is processed, increasing the risk of side effects. Allergic reactions: Anyone who has had an allergy to sildenafil or similar medications should avoid Penegra. Certain eye disorders: People with conditions like retinitis pigmentosa or a history of sudden vision loss should consult a doctor before use. In short, Penegra 100 mg should be stopped or avoided by anyone with serious heart issues, blood pressure problems, organ impairment, or allergies to sildenafil, as well as anyone taking nitrates.