Report your injury to your supervisor or manager immediately, regardless of whether or not you think you will need medical treatment.  Ideally, it would be best for your supervisor to write a written accident report and for you to get a copy of that report.  Many jobs are physically demanding and with many jobs you have aches and pains every day.  However, if you think it’s a minor injury that will go away in a day or two and you don’t report it and it ends up not being a minor injury, then you have given the insurance adjuster an opportunity to deny your claim and make you fight for your benefits at a hearing in order to resolve the issues.  This happens often with back injuries when you may feel a little twinge when you lift a box but continue to work and by the next day you can’t even get out bed because you’re in such pain.  If you had reported it when it occurred, even though it was minor, they would not be able to contest it.  You must give your employer 30 days notice of any accident but immediately is best.