I am a 45-year-old man who had been experiencing what I would describe as mild erectile dysfunction for about a year -- not a complete inability to get erections, but a noticeable decrease in firmness and reliability compared to my thirties. My doctor ran blood work and everything came back normal. He suggested lifestyle changes (which I was already doing -- regular exercise, healthy weight) and offered to prescribe sildenafil, but I wanted to try a supplement approach first.
I found the Cormio et al. study from 2011 showing that 1.5g/day of L-Citrulline improved erection hardness scores in men with mild ED, and decided to try a higher dose based on the pharmacokinetic data suggesting dose-dependent arginine elevation. I settled on 3g twice daily, morning and evening, for a total of 6g/day.
Week 1-2: No noticeable change. I was not expecting immediate results based on my research, so this was not discouraging.
Week 3: The first sign was improved morning erections. I woke up on a Tuesday with the kind of morning wood I had not experienced in probably two years -- firm, persistent, and lasting well beyond the alarm. This happened intermittently for the rest of the week.
Week 4-6: The improvement became more consistent. Erections during sexual activity were noticeably firmer. Not the steel-rod hardness of my twenties, and nothing approaching what I imagine Viagra would produce, but a meaningful improvement from baseline. My partner noticed and commented without me mentioning the supplement. The best way I can describe it is that my erections went from a 6 out of 10 to a solid 7.5 -- not a transformation, but enough to make a real difference in satisfaction and confidence.
What did NOT change: spontaneous erections did not increase. Libido was not affected (this is consistent with citrulline's mechanism -- it improves blood flow, not desire). There were no side effects whatsoever. No headaches, no flushing, no nasal congestion, none of the PDE5 inhibitor side effects.
I have continued taking it daily. The effect seems to maintain at a steady state with no tolerance developing. For men in a similar situation -- mild difficulties, not severe ED -- I think citrulline is worth trying before jumping to pharmaceuticals. Just set your expectations realistically. This is not a substitute for Cialis. It is a modest, natural improvement in vascular function that happens to benefit erectile quality among other things.