Does workers’ compensation cover pre-existing conditions?

Workers' Compensation - April 2, 2025 by Horwitz, Horwitz & Associates

Many injured workers worry that insurance companies or employers will use their past medical history as an excuse to deny or reduce their claim.

At Horwitz, Horwitz & Associates, our Chicago workers’ compensation attorneys understand how state law is supposed to protect workers—even those with pre-existing conditions. This guide will explain whether workers’ compensation covers pre-existing conditions, how aggravation of a previous injury impacts your claim, and what steps you can take to maximize your benefits.

does workers comp cover pre-existing conditions

Does workers’ compensation cover pre-existing conditions in Illinois?

Illinois workers’ compensation law (820 ILCS 305/1) states that employees are entitled to benefits if their injury arises out of and in the course of employment. This includes pre-existing conditions that are aggravated or worsened by workplace duties.

For example, workers’ compensation may cover:

  • A back injury made worse by heavy lifting at work
  • A prior knee condition aggravated by standing or walking for long hours
  • Carpal tunnel syndrome worsened by repetitive motion tasks
  • A heart condition exacerbated by work-related stress or exertion

Employers cannot deny a claim simply because you had a previous injury or medical condition—what matters is whether your job worsened your condition.

How does Illinois workers’ compensation handle pre-existing conditions?

Illinois law protects injured workers with pre-existing conditions under the “Aggravation Rule.” This rule states that if a workplace accident or job duties make a prior injury or condition worse, the worker is entitled to compensation.

Under Thomas v. Industrial Commission, an important Illinois case, the court ruled that:

  • Workers are eligible for compensation if their job aggravated, accelerated, or worsened a pre-existing condition.
  • The employer must compensate the worker for the worsening of the condition—not the underlying condition itself.

This means if a work injury accelerates your arthritis, worsens a previous back injury, or makes an old surgical injury painful again, you may still qualify for benefits.

What If my employer denies my claim due to a pre-existing condition?

Unfortunately, many employers and insurance companies try to deny or minimize claims by arguing that the injury was not work-related or that it was a pre-existing condition unrelated to job duties.

If your employer or insurer denies your claim, here’s what you should do.

1. Gather medical evidence

  • Obtain medical records showing your condition before and after the workplace injury.
  • Ask your doctor to provide a written statement explaining how work worsened or aggravated your condition.

2. File an appeal with the Illinois Workers’ Compensation Commission (IWCC)

If your claim is denied, you have the right to appeal through the Illinois Workers’ Compensation Commission (IWCC). An experienced workers’ compensation attorney can help you file a strong appeal and fight for the benefits you deserve.

3. Do not settle for less than you deserve

Employers may pressure workers with pre-existing conditions to accept a lower settlement or drop their claim altogether. Do not sign any settlement agreements without first speaking to a lawyer.

What workers’ compensation benefits can you receive?

If your pre-existing condition was aggravated by work, you may be eligible for several types of workers’ compensation benefits, including:

  • Medical expenses – Covers doctor visits, surgeries, therapy, and prescriptions.
  • Temporary Total Disability (TTD) – Pays two-thirds of your average weekly wage if you are unable to work due to your injury.
  • Permanent Partial Disability (PPD) – If the injury results in permanent impairment, you may receive additional compensation.
  • Vocational rehabilitation – If you cannot return to your previous job, you may qualify for job retraining programs.

Illinois workers’ compensation law does not require you to prove fault—as long as your job contributed to your injury, you are entitled to benefits.

How to strengthen your workers’ compensation claim

If you have a pre-existing condition, taking the right steps can increase your chances of approval.

1. Report your injury immediately

  • Illinois law requires workers to report injuries within 45 days (820 ILCS 305/6(c)).
  • The sooner you report it, the stronger your case against employer disputes.

2. Get a medical evaluation

  • Visit a doctor familiar with workers’ compensation cases.
  • Be honest about your medical history, but emphasize how your job worsened your condition.

3. Keep detailed records

  • Document pain levels, work restrictions, and medical treatments.
  • Save emails, witness statements, and injury reports that prove your injury was work-related.

4. Consult a workers’ compensation lawyer

  • Pre-existing condition claims are often challenged—a lawyer can fight employer pushback and maximize your compensation.
  • An attorney can file an appeal with the IWCC if your claim is denied.

How Horwitz, Horwitz & Associates can help

At Horwitz, Horwitz & Associates, we have over 100 years of experience fighting for injured Illinois workers. Our dedicated workers’ compensation attorneys can help you:

  • Prove that your workplace aggravated your pre-existing condition.
  • Obtain medical evidence and expert testimony.
  • Challenge unfair claim denials.
  • Negotiate with insurance companies to secure maximum benefits.

We handle all workers’ compensation cases on a contingency fee basis, meaning you pay nothing unless we win your case.

If your workers’ compensation claim was denied or if you need help proving your case, contact Horwitz, Horwitz & Associates today at (800) 985-1819 for a free consultation. We will fight to get you the benefits you deserve so you can focus on recovery, not financial stress.