Chronic fatigue syndrome (CFS) symptoms usually start suddenly. But for some people, they develop gradually over weeks or months. Symptoms can change in a day, and from day to day. They tend to stop (remission) and then start again (relapse).
There is broad range of CFS symptoms. But there is a core set of symptoms that affect nearly everyone with CFS. These core symptoms are:
Extreme physical fatigue, mental fatigue, or both. It can be constant, or it can come and go. It is not relieved by rest. This fatigue also is so severe that it interferes with your work, your play, and your social activities.
Feeling unwell after being active. This can mean you feel ill or weak or your CFS symptoms are worse. There can be a delay before it starts. It can take more than 24 hours to feel better.
Pain, which can be widespread or in one place. CFS pain can be in one area, then move to another. You may have:
Muscle pain. Joint pain. Headache.