The reason why opioids are so effective at relieving pain is also the reason why they can be so addictive. Your brain and nervous system naturally contain opiate receptors, which act as your body’s natural painkillers. When you take opioids, the medications interact and bind with these receptors. This not only blocks the pain signaling, but also triggers reward centers in your brain.

By tamping down your natural ability to fight off pain and stimulating your reward centers, these receptors begin to create new neural pathways that favor opioid use — in effect rewiring your brain to receive the drug.

And the longer you take the opioid medication, the more your body builds up a tolerance toward the substance, which leads to needing more to achieve the same pain-relieving and euphoric effects.

Please note that “rewiring” is a very simplistic term for what happens in your brain when an addiction forms. The new neural pathways cause existing pathways to shut down, in effect becoming becoming the dominant network in your brain, which can lead to the hallmarks of addiction, including:

• Uncontrollable cravings
• The inability to stop using
• An overriding obsession with using

These side effects often lead to behavioral issues, such as risk taking and isolation.