Israeli troops fired tear gas and rubber bullets at protesters who called for the release of Samer Issawi, who has been on an on-again, off-again hunger strike for several months.
Three journalists have also been reportedly among the injured.
The prisoner issue is an emotional one for Palestinians, who generally view prisoners as heroes.
The Palestinian minister of prisoner affairs, Issa Qaraqe, said Issawi began his fast in August and has been observing it intermittently.
Qaraqe said Issawi had lost 35 kilograms (about 77 pounds), has kidney pain and has lost feeling in parts of the right side of his body. He said there are four prisoners on hunger strike.
Human rights groups have warned of their worsening health.
"If, God forbid, any prisoner dies of hunger strike inside the prison, the situation on the ground will deteriorate," Qaraqe said. "People won't stand for any prisoner to die of a hunger strike."