"Contact of 1,1,1,2-tetrafluoroethane with flames or hot surfaces in excess of 250 °C (482 °F) may cause vapor decomposition and the emission of toxic gases including hydrogen fluoride and carbonyl halides.[18] 1,1,1,2-Tetrafluoroethane itself has an LD50 (lethal concentration for 50% of subjects) in rats of 1,500 g/m³, making it relatively non-toxic. However, its gaseous form is denser than air, and will displace air in the lungs. This can result in asphyxiation if excessively inhaled.[19][20] This is what contributes to most deaths by inhalant abuse."
Only poisonous if you try to kill yourself with it, essentially.
