Obtain a doctor's excuse for work by making an appointment with your physician and having a physical examination. When the doctor confirms the illness or injury, explain the circumstances of your work, and ask the doctor to write a letter to your employer, states Alison Doyle for About.com.
Doctor's letters to employers should include a brief explanation of the necessity of the medical visit, a recommendation for a length of absence from work and recommendations for work accommodations the patient may need, according to Doyle. Obtaining a doctor's excuse letter is an important protection for ill or injured employees because it provides them with formal documentation of the illness or injury in case an employer attempts to fire them or withhold promotion due to absences. Under the Americans with Disabilities Act and the Family Medical Leave Act, it is illegal for employers to fire ill or injured employees.