Why is it that my penis does not stay erect long enough to have sex?

Here are some ...: It would be beneficial to check out if your inability to sustain erection to complete coitus is related with certain illnesses affecting nerve /circulation, premature attempt to resume coitus before a full recovery from orgasm/ejaculation, certain drugs, even low-T, etc. before recommending its remedy. Meanwhile, practicing healthy lifestyle without obsession is the must for all healthcare.