Sexual side effects of Heroin withdrawl

My boyfriend has been doing heroin for years he just recently quit, when is was on this drug he could stay errect for quit some time, but quite soon after he stopped the abuse he is having trouble staying errect. My question would be is there need for a prescription drug like Viagra to help him or will he soon be over this symtom? Is this just a symtom that will go away after time or do you think that we will need to consult a physician?