Calling in sick to work -- or "calling out," depending on your company's lingo -- is never a fun task. Whether you are legitimately sick or simply in need of a day off, you may be wary of the third degree from your boss. Much depends on your history of calling in sick and how frequently you have done it. If you're known for calling in sick multiple times, you could suffer even more scrutiny from your boss. Another factor to consider is how heavy the anticipated work load is for the day and how much of a bind your co-workers will be in due to your absence. Keeping the call simple is the best method, regardless of your situation.
Notify your boss as soon as possible. Your management -- and co-workers -- will appreciate it if you give them ample time to adjust to your absence. This applies not only to phone calls but also in person notifications, if you happen to fall ill while at work.
Explain how your illness could adversely affect your job performance. If the boss thinks that you are able to work but choose not to, your conversation will be more awkward. The more your boss understands that you genuinely need to be at home, the smoother the conversation will go.
Keep it brief. If you are expecting your boss to doubt the legitimacy of your claim to being sick, it is tempting to overdo it by giving her details she doesn't need to know. However, this can backfire, as she might think that you are being dramatic for effect.
Speak directly to your boss. Although you may be tempted to choose the easiest route, emails and phone messages are not recommended as they may cause your boss to question your credibility. Not connecting directly with the boss gives the appearance that you have something to hide.