Hello. During sex my penis didn't come hard. Doctor advise me to take herberex tablets but this tablet work only for timing and I want penis hard forever?

Sex herbs. In your twenties, there is no reason you should suddenly be developing impotence problems. This could come from medication, poor blood flow, diabetes, or vascular diseases. I would start with discussing this with your family physician. As to the herb, there is no herb I know of that reliability helps with maintaining erection. Another possibility is trust issues with your sexual partner. .