Is Meditation a cure or just fighting of symptoms?

I meditate daily for 30 minutes, and right after each session my mind is very calm, centered, stable; I just exist in the present moment without much thinking. However, after a while, the compulsive thinking comes back, wants to drag me towards unhappiness. I feel this is like an illness. Therefore, is meditation a cure to this illness (will it go away one day if I meditate more/longer? What should I do?) or is it just a temporary easing of symptoms? I want to cure the illness. Thanks.