Doing botox for forehead wrinkles can leave some patients unhappy because it does sometimes cause more heaviness of the brows (the muscles that elevate the brows are paralyzed by the botox and no longer function as they should). As far as tightness, I am assuming that you are referring to your skin being more firm and less wrinkled, but I'm not as sure how to answer that question as I'm not entirely sure what you are referring to. In most people, the duration of action of Botox is approximately 3 months, so you should start to notice some improvement in the heaviness by at least month 3 after injection. I wouldn't necessarily give up on Botox injections for your forehead wrinkles, but it may need to be injected a little higher in your forehead to avoid the heaviness feeling. Best of luck!