I've been on adipex 37.5 for over a month, now noticing i can't keep an erection, and very little sensation. if i stop adipex will it return to normal?

Try stopping med: Any drug can have any side effect and each person is a little bit different. I have never seen this particular side effect with Adipex (Phentermine), but that doesn't mean it is not the cause. I would stop the medication and see if there is any improvement. Discuss alternative medications with the prescribing doctor...as well as possible treatment of the erectile dysfunction.