May make this condition worse. Sildenafil Viagra is used to treat erectile dysfunction impotence; inability to get or keep an erection in men. Do not use this medicine if you are also using a nitrate medicine, often used to treat angina or high blood pressure. Before taking sildenafil, tell your doctor and pharmacist if you are allergic to sildenafil, any other medications, or any of the ingredients in sildenafil tablet or suspension. Healthcare providers have experience talking about ED and providing treatment options without any judgment or shame. However the dose is usually not more than 40 mg 3 times a day. · For treatment of erectile dysfunction: For oral dosage form (tablets): Adults up to 65 years of age—50 milligrams (mg) as a single dose no more than once a day, 1 hour before sexual intercourse. Alternatively, the medicine may be taken 30 minutes to 4 hours before sexual intercourse. Your doctor may adjust your dose if needed. Dizziness, headache, flushing, or stomach upset may occur. Vision changes such as increased sensitivity to light, blurred vision, or trouble telling blue and green colors apart may also occur. If. The dose of Cialis you need will depend on whether you’re taking it daily or as needed. Daily doses are often between and 5 milligrams (mg). The as-needed dose is usually 10 mg but can range from 5–20 mg. The typicaldose of Viagra is 50 mg. However, the dosage can range from 25– mg.