Hi Jayne
You may want to show your GP the clip below taken from the NICE guidelines. This is what they recommend for men with ED following radical treatment. PDE5 is viagra
Bri
Managing adverse effects of radical treatment
Sexual dysfunction
1.3.31 Ensure that men have early and ongoing access to specialist erectile dysfunction services. [2008, amended 2014]
1.3.32 Offer men with prostate cancer who experience loss of erectile function phosphodiesterase type 5 (PDE5) inhibitors to improve their chance of spontaneous erections. [2008]
1.3.33 If PDE5 inhibitors fail to restore erectile function or are contraindicated, offer men vacuum devices, intraurethral inserts or penile injections, or penile prostheses as an alternative. [2008]