The rapid pace of living today may cause occasional tiredness or fatigue; however, the problem usually resolves when adequate sleep and/or rest is obtained and the activities that provoked the fatigue are stopped. But what if the fatigue continues? Fatigue lasting one month or longer is known as prolonged fatigue; if it persists six months or longer, it is classified as chronic.
As much as one-fourth of Americans report one or more episodes of fatigue lasting from two weeks to one month or longer. The majority never identify a medical cause for the fatigue. However, at least 18% do have identifiable preexisting illnesses that are causal. In any case of prolonged fatigue, a physician’s diagnosis is vital.
Possible CausesFatigue is common in many disease states; thus, it should be treated as a symptom rather than a diagnosis.[3,4]
Iron-deficiency anemia can produce fatigue in patients conducting normally nonstressful tasks, such as walking up stairs.
Caffeine is normally considered a stimulant, but in some patients, continued abuse results in fatigue. Self-medicating with additional caffeine to gain relief simply worsens the fatigue. Withdrawal from caffeine addiction also produces fatigue.
Fatigue and weakness are symptoms of cancer. Cancer patients complaining of fatigue should be referred to their oncologist or general practitioner for evaluation.
Fatigue is common in fibromyalgia. Investigators compared women with fibromyalgia to sedentary women who were otherwise healthy and found that those with fibromyalgia scored their fatigue as 69 on a visual analogue scale, yet the healthy controls scored fatigue as 32. The groups were not significantly different in cardiovascular fitness.
Patients experience fatigue when they do not take in adequate calories and become hypoglycemic. Others develop fatigue-inducing rebound hypoglycemia after sugar ingestion (e.g., sugared soft drinks).
A variety of heart and lung-related conditions can cause fatigue, including angina, atherosclerosis, congestive heart failure, hypertension, and pulmonary infections (e.g., pneumonia). Severe emphysema also induces fatigue due to inadequate oxygenation.
Some infections result in a prolonged recovery time, in which the patient feels fatigued or tired. The etiology may be due partly to sleep disruption induced by the infection, or to alterations in the hypothalamic-pituitary-adrenal axis. If postinfection fatigue syndrome is severe, the pharmacist should refer the patient to a physician.
Severe obesity (body mass index equal to or exceeding 45) is often associated with fatigue. BMI is determined by dividing the patient’s weight in kilograms by the height in meters squared.
Several psychiatric disorders can result in chronic fatigue, including depression, bipolar affective disorder, schizophrenia, delusional disorders, dementias, and either anorexia nervosa or bulimia nervosa.