Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day. When hypertension occurs in the lungs, the heart must work harder to pump enough blood through the lungs. Children—Use is not recommended. Side effects Side effects of oral ED medicines are often mild. If you have an erection that lasts more than 4 hours, get medical help right away. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. A newer form of the medicine that dissolves on the tongue might work faster than the pill that you swallow.But the maximum dose of Viagra is mg. Dosage questions. Below, we answer some common questions related to Viagra’s dosage. For example, sildenafil mg, mg, .  · a light-headed feeling, like you might pass out. Common sildenafil side effects may include: flushing (warmth, redness, or tingly feeling); headache, dizziness; heartburn, nausea, or upset stomach. abnormal vision (blurred vision, changes in color vision) runny or stuffy nose, nosebleeds; sleep problems (insomnia); or. The maximum recommended dosage of Viagra is mg per day. Taking higher doses of Viagra can increase your chances of having severe side effects, such as: dangerously .