Researchers from the Institute of Molecular and Cellular Pharmacology looked at venom from 50 species before they found the Black Mamba's pain-killing proteins - called mambalgins, the BBC News reported.
The predator uses neurotoxins to paralyse and kill small animals and is one of the fastest and most dangerous snakes in Africa.
Tests on mice showed its venom also contained a potent painkiller.
"When it was tested in mice, the analgesia was as strong as morphine, but you don't have most of the side-effects," researcher Dr Eric Lingueglia, said.
Tests on human cells in the laboratory have also showed the mambalgins have similar chemical effects in people.
Morphine acts on the opioid pathway in the brain. It can cut pain, but it is also addictive and causes headaches, difficulty thinking, vomiting and muscle twitching.
More From This Section
The researchers said mambalgins tackle pain through a completely different route, which should produce few side-effects.
The study was published in the journal Nature.