What is weakness or fatigue?
A person with weakness or fatigue constantly lacks energy, or feels weary and tired. Weakness and fatigue is a very common complaint that occurs with many illnesses, including infections, heart disease, lung disease, neurological disease, autoimmune disease, and brain disease.

What are the symptoms of weakness or fatigue?
Weakness or fatigue can accompany many other symptoms. Symptoms that may occur with severe weakness and fatigue include faintness, fainting, palpitations, chest pain, difficulty breathing, or confusion.

How does the doctor treat weakness or fatigue?
The treatment for weakness or fatigue depends on the cause. Treatment may not be necessary in adolescents and young adults. In general, treatment for weakness or fatigue includes a healthy diet, exercise, and regular sleep.