Complete BNF Contraindications and Warnings
Dangerous Drug Combinations to Avoid
The BNF clearly states that sildenafil must never be taken with nitrate medications including GTN spray, isosorbide mononitrate, or isosorbide dinitrate. This combination can cause a dangerous drop in blood pressure that may be life-threatening. Riociguat, used for pulmonary hypertension, is also contraindicated with sildenafil treatment.
Cardiovascular Contraindications
According to BNF guidelines, sildenafil should be avoided in men with severe heart disease, recent heart attack or stroke within six months, or very low blood pressure. Those with unstable angina or severe heart failure should not use sildenafil. A cardiovascular assessment is essential before starting treatment.
Medication Interactions Requiring Caution
Alpha-blockers used for prostate problems or blood pressure may interact with sildenafil, potentially causing dizziness or fainting. The BNF recommends starting with lower doses if these medications cannot be avoided. Strong CYP3A4 inhibitors like ketoconazole or ritonavir may increase sildenafil levels, requiring dose adjustment.
Medical Conditions Requiring Careful Assessment
Men with active peptic ulcers, bleeding disorders, or anatomical penile abnormalities need specialist evaluation before sildenafil use. Those with severe liver or kidney impairment may require dose reduction or alternative treatments. Vision problems, particularly NAION (non-arteritic anterior ischaemic optic neuropathy), warrant immediate medical attention.
Lifestyle Factors to Consider
The BNF advises limiting alcohol consumption as it may worsen erectile function and increase side effects like dizziness or headaches. Grapefruit juice should be avoided as it can affect how sildenafil is metabolised. Patients can choose between branded Viagra or generic sildenafil at EverydayMeds, with both options following the same BNF safety guidelines.
