Does l-citrulline help in cases of ed?

Yes. Works best if combined with l-arginine. Look up proargi-9 as a good brand. I take that myself for heart and overall vascular health. Remember - if you don't keep your heart and blood vessels healthy your penile vascular health will suffer as well - those blood vessels are about half the diameter of your coronary arteries! ed frequently preceeds an mi by 6-12 months!
Never tried it. But i would doubt it unless you have something wrong with a biochemical mechanism that processes urea.