Take treatment for GAD by Prozac 40 mg, my GP wants add either Buspar (buspirone) or Wellbutrin to encounter side effects of Prozac, which the safe and ideal combo?

Buspirone . You may want to talk to your doc about a psychiatry referral since it sounds like (a)he may be in over their head. Buspirone is an anti-anxiety drug, but both Prozac and Wellbutrin (bupropion) can potentially exacerbate anxiety. There are many other potential options if Buspirone is not beneficial, but I would not abandon it before max dose of 60 mg/d. It should be taken 3-4 times dailu.