It lasts 4 to 5 hours, or longer if you have mild to moderate ED. Push the plunger of the syringe, then insert the tip into the bottle while holding the bottle upright on a flat surface. Children 1 year of age and older weighing 45 kilograms kg or more—20 mg 3 times a day. In pulmonary hypertension it works by relaxing blood vessels in the chest. Storage Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Never take an extra dose to make up for a forgotten one. The most common side effects are headaches, feeling sick, indigestion and dizziness.Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when you get sexually excited. For sildenafil to work properly, you’ll need to be sexually excited. Dosage and strength for pulmonary hypertension. Sildenafil tablets for pulmonary hypertension come in 10mg and 20mg strengths. The usual adult dose is 20mg taken 3 times a day. Doses for children can range from 10mg to 20mg taken 3 times a day, depending on their weight. 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 .