Dual diagnosis means you have a mental health condition and a substance use disorder at the same time. It could be depression paired with alcohol use, anxiety alongside opioids, or PTSD that shows up next to stimulant use. This overlap is common. Most people who come in for addiction treatment are also dealing with something underneath it. Dual diagnosis treatment addresses both problems together, because treating one and ignoring the other usually leaves you stuck. You get care for the addiction and the mental health condition in the same place.