Fatigue is a symptom, not a diagnosis
Feeling tired can follow a demanding day, poor sleep, emotional stress, or physical exertion. But fatigue that lasts for weeks, keeps returning, or makes ordinary tasks difficult can signal an underlying problem. The National Institute on Aging lists possible contributors such as anemia, infections, heart, kidney, liver, thyroid, or lung disease, sleep apnea, pain, depression, and medication effects.
Because these causes require different responses, it is not safe to assume that persistent fatigue means the mitochondria need nutritional support. A supplement may distract from finding a treatable cause.
Prepare for a useful appointment
Write down when the fatigue began, whether it is constant or comes and goes, what makes it worse, how sleep has been, and any other symptoms. Bring a complete list of prescription medicines, over-the-counter products, and supplements. Mention recent illness, changes in appetite or weight, pain, mood changes, and new exercise limitations.
A clinician may decide whether an examination or laboratory tests are appropriate. The right evaluation depends on the person's age, history, symptoms, and medications. Do not stop prescribed treatment or start a high-dose supplement on your own while waiting for answers.
Know when symptoms are urgent
Severe or sudden symptoms such as chest pain, serious shortness of breath, fainting, confusion, sudden weakness on one side, or a new severe headache require urgent assessment. Do not attempt to treat an emergency with a dietary supplement.