The best approach to call in sick is for the employee to call and offer an honest, simple statement that indicates the he is unable to work. Trying to act sick or exaggerate claims of illnesses may raise suspicion even when the worker is sick.
The nature of a person's work may affect the message. Someone who works on a team or in close quarters with others may say, "I have a bad virus and I don't want to spread the germs." For a job that requires high energy and enthusiasm, a person may say, "This fever is wiping me out. I simply don't have the energy to work today." As long as someone doesn't use excessive sick days, employers have little reason to question these calls.