Pentazocine works by changing the way the brain and spinal cord perceive pain.

Specifically:

• It is a kappa-opioid receptor agonist, meaning it activates kappa opioid receptors in the central nervous system. This blocks or reduces the transmission of pain signals, providing pain relief.
• It is also a partial agonist/antagonist at the mu-opioid receptor. This means it activates mu receptors only weakly while also blocking stronger opioid effects. Because of this, pentazocine has a lower risk of respiratory depression and misuse than full opioid agonists like morphine, although these risks are not eliminated.