You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. Sildenafil is also used in both men and women to treat the symptoms of pulmonary arterial hypertension. Shake the liquid well for 10 seconds before each use to mix the medication evenly. Do not take a double dose to make up for a missed one. Tell your doctor or pharmacist if you are taking nitrates medications for chest pain such as isosorbide dinitrate Isordil , isosorbide mononitrate Monoket , and nitroglycerin Nitromist, Nitro-Dur, Nitrostat. · a light-headed feeling, like you might pass out. Common sildenafil side effects may include: flushing (warmth, redness, or tingly feeling); headache, dizziness; Missing: jelly.  · For oral dosage forms (suspension or tablets): Adults—20 milligrams (mg) 3 times a day. Your doctor may adjust your dose as needed and tolerated. However, the . Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. Missing: jelly.