If you're hurt on the job, don't try to tough it out and keep it to yourself. You may be embarrassed about getting hurt or tempted to think it's no big deal. However, there are some very important reasons to file the report -- one of which is that you need proof that you were injured in the first place.
This becomes very important if your injury is such that you can't do your job as well as you usually do, even for just a short time. For example, if your job involves moving pallets around a warehouse, and you hurt your back, you may not be able to pull the pallets as quickly as you usually do, or you may not be able to pull them at all.
Naturally, this is going to impact your production. Your boss may then come to you and tell you that you're fired for not hitting the right numbers for the day.
Of course, you may then decide to tell your boss that you were hurt, trying to explain the situation. However, it could already be too late. What you want is some proof of that injury, and you don't have it. Your boss could claim that you're making the injury up to excuse laziness and fire you anyway.
This feels very unfair, and it could be. However, without proof that you were hurt, there may not be a lot you can do. It will at least make it far harder for you to get the benefits you deserve and to get your job back.
To avoid this, make sure you know how to report an injury and when to file a workers' comp claim in Illinois after a work-related accident.
Source: Can My Boss Do That?, "Hurt on the Job," accessed May 06, 2016