Hello dear, First of all...the size of penis is determined genetically & it won t grow after a certain limit And the medications like Sildenafil citrate (Viagra) maintains erection by increasing blood flow to the penis. Performance can be improved by having a diet rich in fruits, vegetables, fish, nuts & honey. You can also do oil massage of the penis...it increases blood flow & maintains the erection. Avoid smoking & alcohol. One more thing...avoid consuming any over the counter medication which claim to increase the size or improve performance...it may be harmful. Best thing is to eat a healthy diet, exercise regularly, avoid stress, get good sleep, think positive and stay happy. Wishing you Good Health. Thanks and take care.