What are the effects of diazepam (valium) and clonazepam on flaccid penis and erections?

They don't help. Neither diazepam nor Clonazepam will help erectile dysfunction. There are also reports of sexual dysfunction with all benzodiazepines. Though not well understood, the mechanism of these problems could be via gamma-aminobutyric acid receptors in the midbrain central gray or ventral tegmental area. However, this is mixed with issues stemming from anxiety itself. Hoping you work w/urologist too.
Why is the dog on ? Just kidding. Nice picture. Both can make it difficult to obtain and maintain an erection. Either consult one of the healthtap urologist who can better explain the physiology or healthtap apps. Discuss with prescriber since i presume it's being taken for anxiety and their are other options which still could cause or contribute to the problem but might not. T/c urology/endocrine w/u, then psych rx.