Recent clinical studies support the use of progesterone for treating traumatic brain injury (TBI). One trial found that the mortality rate of subjects with moderate to severe adult TBI, who were given progesterone intravenously for three days after the injury, was less than half of that among control subjects. These subjects were still doing better 30 days later. A second study found similar results, and neither study found any serious adverse effects.

Studies involving animals also support the use of progesterone in the treatment of acute stroke. This research indicates that progesterone protects the brain against damage caused by lack of blood flow, and it may also reduce the size of the blood clot involved.