The generic name of the drug Viagra is Sildenafil Citrate, and its side effects include flushing, headache, dizziness, and nasal congestion, which are not significantly harmful when used correctly. Sildenafil Citrate diastolizes the corpus cavernosum, increases blood flow and improves erectile function in men. This product needs to be taken as needed before sexual activity, used up to once a day, and is recommended to be used every other day. Proper use of this product is not harmful. Common side effects of this product include dizziness, flushing, headache, back pain, limb pain, indigestion, nausea, nasal congestion, and visual abnormalities. It is contraindicated in patients with known allergy to sildenafil, those taking nitrate drugs, etc. It is recommended to use the drug under the guidance of a doctor and should not be taken blindly.