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Weakness is the feeling of body fatigue, or tiredness. A person experiencing weakness may not be able to move a certain part of their body properly. They may also experience tremors, which are uncontrollable movements, or twitches in the area of weakness.

Some people experience weakness in a certain area of their body, such as the arms or legs. Others may experience full-body weakness, which is often the result of a bacterial or viral infection such as influenza or hepatitis. Weakness may be temporary, but it’s chronic or continuous in some cases.

What Causes Weakness?

Common causes of weakness include:

  • the flu
  • thyroid disease
  • anemia, which can occur from excessive loss of blood during menstruation
  • depression
  • a lack of sleep
  • poorly controlled or undiagnosed diabetes
  • congestive heart failure
  • vitamin B-12 deficiency
  • medication side effects, which often occur when taking mild tranquilizers to treat anxiety
  • polymyositis, which is an inflammatory muscle disease
  • chemotherapy

Other causes of weakness include:

  • cancer
  • stroke
  • a heart attack
  • nerve or muscle injuries
  • diseases affecting the nerves or muscles
  • medication overdose
  • vitamin overdose
  • poison

Although weakness caused by cancer may appear slowly over an extended amount of time, weakness caused by a heart attack or stroke often occurs immediately.

In addition to experiencing weakness, other symptoms such as difficulty breathing, pain, and irregular heartbeat may occur. Call 911 if you experience sudden weakness. Don’t try to drive yourself to the hospital.

What Are the Symptoms of Weakness?

Isolated Weakness

If you feel weak in one area of your body, you may find that you can’t move that part of your body efficiently. You may also experience:

  • delayed or slow movement
  • uncontrollable shaking, or tremors
  • muscle twitching
  • muscle cramps

Full-Body Weakness

Full-body weakness causes you to feel run down, similar to the feeling you get when you have the flu. This is known as fatigue, but it’s also possible to experience full- body weakness without feeling tired.

Some people who experience full-body weakness also experience fever, flu-like symptoms, or pain in the affected area.

Dangerous Symptoms

You should contact your doctor if you experience any of the following symptoms:

  • dizziness
  • lightheadedness
  • confusion
  • difficulty speaking
  • changes in vision
  • chest pain
  • difficulty breathing

How Is the Cause of Weakness Diagnosed?

There are many treatment options for weakness. Determining the underlying cause helps your doctor determine the best method of treatment. When you visit your doctor, they’ll go over your symptoms. They’ll ask you when you began experiencing symptoms. This will give your doctor some ideas about what may be causing you to feel weak.

Your doctor may request that you give a urine sample. They may also take a blood sample from you and send it to a lab for testing. The lab will test these samples for signs of infection and possible medical conditions that may cause weakness. If you’re experiencing pain, your doctor may also order an imaging test to have a look at the area. Imaging tests may include:

  • X-rays
  • MRI scans
  • CT scans
  • ultrasounds

Your doctor will order a brain scan and electrocardiogram if they suspect you’re having or have had a heart attack or stroke.

What Are the Treatment Options for Weakness?

Once your doctor diagnoses the cause of weakness, they’ll discuss treatment options with you. Treatment may not be necessary if the weakness is due to a cold or the flu.


If you’re dehydrated, increasing your fluid intake can help. However, if you’re showing severe symptoms of dehydration, you may require hospital treatment. At the hospital, you’ll receive fluids through an intravenous line. You may also need medication to increase your blood pressure. At this point, the weakness may begin to subside.


If the cause of your weakness is cancer, your doctor will provide you with treatment options. The stage, location, and body structure involved all help to determine a good course of treatment. Treatment options for cancer include chemotherapy, radiation treatment, and surgery.

Chemotherapy and other cancer treatments can also cause weakness.

Blood Loss

If your weakness is due to blood loss, you may need iron supplementation if it appears that you’re iron deficient. You may need a blood transfusion if your anemia is severe. If you need a blood transfusion, you’ll receive one in the hospital. This treatment consists of receiving donor blood through an intravenous line.

Heart Attack

Your doctor will provide you with treatment options for weakness caused by a heart attack.

What Is the Long-Term Outlook?

Some of the causes of weakness are a part of normal life. For example, if you have weakness due to a cold, time and rest should eventually clear up your weakness. If you have weakness that originates from a more serious condition, seeing your doctor early and regularly can help you recover from weakness more quickly.

Taking care of your physical health is a good preventive measure. Drinking plenty of fluids, getting adequate rest, and exercising regularly can help your recover from weakness and also prevent it.

Content licensed from:

Written by: April Kahn
Medically reviewed on: Mar 09, 2016: Modern Weng, D.O.

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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