Weakness and fatigue are terms that are often used as if they mean the same thing. But in fact they describe two different sensations. It is important to know exactly what you mean when you say "I feel weak" or "I am fatigued" because it can help you and your doctor narrow down the possible causes of your symptoms.
Both weakness and fatigue are symptoms, not diseases. Because these symptoms can be caused by many other health problems, the importance of weakness and fatigue can be determined only when other symptoms are evaluated.
General weakness often occurs after you have done too much activity at one time, such as by taking an extra-long hike. You may feel weak and tired, or your muscles may be sore. These sensations usually go away within a few days.
In rare cases, generalized muscle weakness may be caused by another health problem, such as:
Muscle weakness that is slowly getting worse requires a visit to a doctor.
Sudden muscle weakness and loss of function in one area of the body can indicate a serious problem within the brain (such as a stroke or transient ischemic attack) or spinal cord or with a specific nerve in the body.
Fatigue is a feeling of tiredness, exhaustion, or lack of energy. You may feel mildly fatigued because of overwork, poor sleep, worry, boredom, or lack of exercise. Any illness, such as a cold or the flu, may cause fatigue, which usually goes away as the illness clears up. Most of the time, mild fatigue occurs with a health problem that will improve with home treatment and does not require a visit to a doctor.
A stressful emotional situation may also cause fatigue. This type of fatigue usually clears up when the stress is relieved.
Many prescription and non-prescription medicines can cause weakness or fatigue. The use of alcohol, caffeine, or illegal drugs can cause fatigue.
A visit to a doctor usually is needed when fatigue occurs along with more serious symptoms, such as increased breathing problems, signs of a serious illness, abnormal bleeding, or unexplained weight loss or gain.
Fatigue that lasts longer than 2 weeks usually requires a visit to a doctor. This type of fatigue may be caused by a more serious health problem, such as:
Myalgic encephalomyelitis/chronic fatigue syndrome
is an uncommon cause of severe, persistent fatigue.
If fatigue occurs without an obvious cause, it is important to evaluate your mental health. Fatigue is a common symptom of mental health problems, such as anxiety or depression. Fatigue and depression may become so severe that you may consider suicide as a way to end your pain. If you think your fatigue may be caused by a mental health problem, see your doctor.
Check your symptoms to decide if and when you should see a doctor.
Health Tools help you make wise health decisions or take action to improve your health.
Many things can affect how your body responds to a symptom and what kind of care you may need. These include:
You have answered all the questions. Based on your answers, you may be able to take care of this problem at home.
Symptoms of serious illness may include:
Symptoms of serious illness in a baby may include the following:
Symptoms of a heart attack may include:
The more of these symptoms you have, the more likely it is that you're having a heart attack. Chest pain or pressure is the most common symptom, but some people, especially women, may not notice it as much as other symptoms. You may not have chest pain at all but instead have shortness of breath, nausea, or a strange feeling in your chest or other areas.
Neurological symptoms—which may be signs of a problem with the nervous system—can affect many body functions. Symptoms may include:
Heartbeat changes can include:
Many prescription and non-prescription drugs can cause weakness and fatigue. A few examples are:
Based on your answers, you may need care right away. The problem is likely to get worse without medical care.
Based on your answers, you may need care soon. The problem probably will not get better without medical care.
Based on your answers, you need emergency care.
or other emergency services now.
After you call 911 , the operator may tell you to chew 1 adult-strength (325 mg) or 2 to 4 low-dose (81 mg) aspirin. Wait for an ambulance. Do not try to drive yourself.
Based on your answers, you need emergency care.
Based on your answers, the problem may not improve without medical care.
If you have generalized weakness and fatigue along with other symptoms, evaluate those symptoms. Home treatment for your other symptoms usually will improve your weakness and fatigue. Mild generalized weakness and fatigue that occur with a viral illness usually improve with the following home treatment measures.
If generalized weakness and fatigue are not related to another illness, follow the guidelines in the Prevention section and be patient. It may take a while for you to feel energetic again.
Call your doctor if any of the following occur during home treatment:
Mild fatigue can often be prevented by changes in lifestyle habits.
You can help your doctor diagnose and treat your condition by being prepared to answer the following questions:
While you are waiting for your appointment, it may be helpful to keep a diary of your symptoms( What is a PDF document? ).
ByHealthwise StaffPrimary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency MedicineAnne C. Poinier, MD - Internal MedicineKathleen Romito, MD - Family MedicineAdam Husney, MD - Family MedicineE. Gregory Thompson, MD - Internal MedicineDavid Messenger, BSc, MD, FRCPC, FCCP - Emergency Medicine, Critical Care Medicine
Current as ofNovember 20, 2017
Current as of: November 20, 2017
William H. Blahd, Jr., MD, FACEP - Emergency Medicine
& Anne C. Poinier, MD - Internal Medicine & Kathleen Romito, MD - Family Medicine & Adam Husney, MD - Family Medicine & E. Gregory Thompson, MD - Internal Medicine & David Messenger, BSc, MD, FRCPC, FCCP - Emergency Medicine, Critical Care Medicine
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