Propane is a colorless and odorless flammable gas at ambient temperatures. It can be toxic when inhaled because it displaces the oxygen in your lungs and essentially prevents your lungs from breathing.
Expectations (prognosis)
Depends on the amount of propane inhaled as well as the duration of exposure. For minimal or short exposures there may be temporary headaches or other mild neurological symptoms. For serious and prolonged exposures there can be permanent damage such as stroke, coma or even death.