What medications treat addiction?

Several. There are several fda approved medications for addiction. For alcoholism: disulfiram, acamprosate, naltrexone. For nicotine addiction: nicotine replacement, bupropion, varenicline. For opioid addiction: methadone, buprenorphine, naltrexone. Many others are being researched.
Addiction. Depends on the substance the person is addicted to, for example Antabuse (disulfiram) or Campral for alcohol addiction.