I started phentermine 37.5 4 days ago, first day nervous, then 2nd and 3rd lots of energy, positive and decreased appetite. Now 4th day, alittle wezzy from time to time and face turned bright red for about 1hr plus like I had wind burn, but I hadn t been outside, it went away. Now the biggie, my erections are hard to keep and when I ejaculate its kind of a numb feeling. Also my penis in the flaccid state seems smaller, testicles pulled up like im cold even when im hot, penis skinner and hard almost, just started today, is this from the weight loss drug, if so will it pass and once off the drug will things return back to normal?