Despite the known health risks of nicotine addiction, numerous people still smoke cigarettes and use other forms of tobacco, and many have difficulty quitting. Nicotine is readily absorbed from tobacco, resulting in an almost immediate response from the chemical epinephrine released from the adrenal cortex and from the chemical dopamine and other chemicals released in the brain’s pleasure and reward systems. Creating a strong desire to repeat the pleasurable feelings nicotine drives the person to use more and more of it. One major step in treatment development occurred when researchers determined that the chemical nicotine is the key addictive component of tobacco. Based on this finding, scientists developed nicotine replacement strategies including the nicotine patch, the nicotine inhaler, and nicotine gum.