Pilates is a very safe form of exercise and injuries of any kind are rare. As with all forms of physical exercise, do not exercise under the influence of drugs or painkillers. I remind you at the beginning of each session that uncomfortable is fine but pain is not - listen to your body- it is tempting to keep up with your neighbour but don't over extend yourself. Before coming to a session it is recommended that you do not eat a heavy meal. Allow 2 hours after eating, but make sure you are not hungry.
If you are in any doubt whether Pilates is a suitable form of exercise for you, please check with your doctor or medical support.