I have been on anti-depressions for years, celxa, paxil (paroxetine) and prozac, i'm don't feel like it helps anymore..can you become immune to it after so long!?

Need increase dose: It is unclear why some meds stop acting after having been effective initially. However increase in dose, change in brand name or to different med does help. Ask your psychiatrist to try Effexor (venlafaxine) or Cymbalta which have slightly different mode of action and do forget role of psychotherapy.

Increased dose : Paxil may be used up to 60 mg, Prozac up to 80 mg, and Celexa up to 40 mg. If you have already been up to these doses and no longer effective, i would recommend Effexor or Cymbalta as next alternatives, but adding Remeron (mirtazepine), wellbutrin, or Abilify (aripiprazole) might also be considered.

Not immune: Immunity doesn't happen, but sometimes people may not respond as well to a single medication over time, or life stresses may cause depression to overtake a medication. The best thing to do is to keep working with your psychiatrist as there are many combinations of medications. Also consider psychotherapy along with medication, as the two together can be more effective. Hope this answer helps.