Weakness or Fatigue with Uncertain Cause

Weakness and fatigue are different conditions. Sometimes, people think they're weak, when in reality, they are fatigued. It's important to understand the difference between weakness and fatigue, so that you can get the right help for how you're feeling.

• Weakness. This is when your muscles aren't as strong as they should be. It can develop quickly or slowly over time. It may affect all of the muscles in the body (generalized weakness) or only one part of the body. Some causes of generalized weakness include a decrease in physical fitness, loss of muscle tissue from long periods of inactivity, abnormal electrolyte levels, and use of certain medicines, such as corticosteroids. Some causes of weakness in specific muscles include strokes, nerve damage, an injured disk in the spine, and neurological disorders, such as multiple sclerosis. Symptoms of weakness depend on which muscles are affected.

• Fatigue. This is when you feel really tired, worn out, or low on energy. It's when you feel a strong need to rest or have so little energy that doing any activity is difficult. It can happen if you're too active or not active enough, stressed, don't get enough good quality sleep, or have an unhealthy diet. Other causes of fatigue include viral infections, emotional problems, especially depression, and severe illnesses, such as heart failure and cancer. Side effects from medicine may also cause fatigue. Fatigue is usually a sign that something else might be going on.

Based on your exam today, the exact cause of your symptoms is not clear. But your symptoms do not seem to be a sign of a serious illness at this time. Keep an eye on your symptoms and get medical advice as directed below.