Opiate blockers are a class of pharmaceutical that bind to pain receptors in the human brain. As a result, opiate based drugs, the narcotics, cannot bind to the same sites and must remain in the bloodstream. Naloxone is one of the most commonly used drugs of this type.
Opiate blockers have an emergency use in the treatment of narcotic overdose. They reverse the nerve suppression of narcotics, restoring normal heart and breathing rates. They are also used in rapid detox procedures in order to prevent withdrawal symptoms.
The main side effect of opiate blockers is that they cannot block the transmission of pain impulses, even by the body's own endorphines. As such, for patients in pain, they block the effect of most painkillers.