Contraindications Nitrates increase cGMP formation, while sildenafil inhibits cGMP degradation causing the combination to produce severe life-threatening hypotension synergistically; coadministration of sildenafil with nitrates is contraindicated. This medicine can cause serious side effects in patients with heart problems. If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when you get sexually excited. Do not take it more than once a day. Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day.Sildenafil is a medication used in the management and treatment of erectile dysfunction and pulmonary arterial hypertension. It is in the phosphodiesterase-5 inhibitor (PDE5-I) class of medications. This activity describes the indications, actions, adverse effects, and contraindications of sildenafil as an agent in the clinical setting. Knowledge . Si vous ressentez une perte soudaine de l’ouïe, parfois accompagnée de bourdonnements d’oreilles ou d’étourdissements, pendant que vous prenez du Sildénafil, appelez votre médecin immédiatement. Le Sildénafil . Viagra comes as an oral tablet in different dosages. Discuss with your doctor what’s an appropriate dose for you. For daily use, Goldstein said, the generic form, sildenafil, comes in mg tablets.