Viagra is the trade name, generic name sildenafil, before taking sildenafil is usually able to eat fish, if you are allergic to fish food can not eat. Sildenafil is a type V phosphodiesterase inhibitor and is mainly used to treat erectile dysfunction. As long as the body is not allergic to fish and other products, you can eat fish in moderation before taking it, and there is no evidence in the literature that food has an effect on the drug. However, if you are allergic to fish and other products, you should not eat them before taking sildenafil. Sildenafil should be used with attention to adverse reactions, such as nausea, vomiting, abdominal pain, increased heart rate, postural hypotension, itchy skin rash. Contraindications: allergy to the drug is prohibited, taking nitrate drugs, prohibited during the period. Specific use of the drug should be under the guidance of a doctor.