Though these are used for psychological purposes for depression, anxiety, neurosis, phobia and many others. But in case of sexual functions such as premature ejaculation this is used to treat the physical aspect of the disease since these SSRI group of medications including paroxetin prolonges the ejaculation time. (Time required to achieve orgasm) Though if erection per say is the problem then it can be physical or psychological, depending on wet dreams, ability to masturbate, and morning erections. For physical problem sildenafil is used. For psychological problems counselling is helpful.

Psychological mostly

Pschychological