Active TB can almost always be cured with medicine, but the medicine must be taken as directed or you risk the bacteria becoming resistant to the medicine. Several medications are used at the same time because there are so many TB bacteria to be killed. TB bacteria die very slowly; it takes at least 6 months for the medicine to kill all of the TB bacteria.
You will probably start feeling better after only a few weeks of treatment. However, the TB bacteria are still alive in your body and if you stop taking the medicine, you will get sick again. You must continue to take your medicine until all the TB bacteria are dead, and you are symptom-free.