Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day. Remove the syringe from the bottle. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. Place the tip of the syringe into you or your child’s mouth and point it towards the cheek. If you experience a prolonged or painful erection for 4 hours or more, contact your doctor immediately. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices.Cialis lasts up to 36 hours in the body, while Viagra lasts 4–6 hours in the body. Both are taken 30 minutes before sex. Cialis can cause limb pain, while Viagra can cause vision change, rash. Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). Viagra can cause side effects that range from mild to serious. .  · Viagra comes as an oral tablet that contains the active drug sildenafil. Sildenafil is also available in generic form. Viagra is classified as a phosphodiesterase type 5 (PDE5) inhibitor.