I am hiv+ and take isentress and truvada. I recently experienced some ED. I get erect but during sex lose my erection and even sensitivity. I got samples of Levitra and Viagra from my physician. last night I took 10mg of Levitra. Within an short time I got an erection, however when I penetrated my partner I lost my erection and even the sensitivity. he was able to get me erect again orally but when I went to penetrate him again I lost the erection. What can I do to make this happen? Would taking 20mg of the Levitra or trying the Viagra which is 50mg be better?