Lethargy can range from simple fatigue to a sign of an underlying medical disorder. Occasional tiredness from stress, poor sleep, or dehydration is common. However, persistent lethargy may indicate anemia, thyroid dysfunction, diabetes, infection, depression, or cardiovascular disease. In severe cases, it can signal neurological conditions or systemic illness requiring urgent evaluation. Associated symptoms such as unexplained weight loss, fever, confusion, shortness of breath, or chest pain increase concern. Medication effects may also contribute. While discussing pharmaceuticals like cephalexin capsules wholesale in a supply context, remember that ongoing lethargy warrants clinical assessment rather than self-medication. Seek professional medical advice for proper diagnosis.