Who Should Not Take Viagra?
Viagra (sildenafil) is contraindicated in patients taking nitrates or nitric oxide donors, such as nitroglycerin, isosorbide mononitrate, or amyl nitrite. These combinations can cause severe, potentially life-threatening hypotension due to synergistic vasodilation.[1][2]
It is also contraindicated in those with known hypersensitivity to sildenafil or any component of the tablet.[1]
What About Heart Conditions?
Viagra is not for use in patients with recent heart attack (within 6 months), stroke (within 6 months), severe hypotension (systolic blood pressure <90 mmHg), or uncontrolled hypertension. Avoid in those with severe cardiovascular disease, including unstable angina or heart failure symptoms.[1][2]
Patients with severe hepatic impairment (Child-Pugh class C) or end-stage renal disease on dialysis should not take it.[1]
Eye and Vision Warnings
Contraindicated in individuals with hereditary degenerative retinal disorders like retinitis pigmentosa, due to rare risks of non-arteritic anterior ischemic optic neuropathy (NAION).[1][2]
Drug Interactions Beyond Nitrates
Do not combine with guanylate cyclase stimulators like riociguat, which treat pulmonary hypertension and can amplify hypotensive effects.[1][2]
How Does Viagra Interact with Other Common Meds?
Alpha-blockers (e.g., doxazosin for hypertension or BPH) require caution and dose adjustments, but are not absolute contraindications if stabilized. Protease inhibitors (e.g., ritonavir) and other CYP3A4 inhibitors demand dose limits to avoid toxicity.[1]
Grapefruit juice can increase sildenafil levels, raising side effect risks—avoid large amounts.[2]
What If You Have These Conditions Anyway?
Consult a doctor for alternatives like Cialis (tadalafil) or non-PDE5 options if contraindications apply. Viagra's label emphasizes screening for cardiovascular risk before prescribing.[1]
Sources
[1]: Viagra Prescribing Information (Pfizer)
[2]: FDA Drug Label for Sildenafil