Thyroid Disease Related Conditions An Overview of Lethargy and Possible Causes By Lana Barhum Lana Barhum Facebook LinkedIn Lana Barhum has been a freelance medical writer for over 10 years. She shares advice on living well with chronic disease. Learn about our editorial process Updated on November 01, 2021 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Ana Maria Kausel, MD Medically reviewed by Ana Maria Kausel, MD Facebook Twitter Ana Maria Kausel, MD, is a double board-certified endocrinologist affiliated with Mount Sinai St. Luke's/Mount Sinai West in New York City. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Symptoms Causes Risks Diagnosis Treatment Frequently Asked Questions Lethargy is not a symptom specific to any one particular disease. Rather, it could be a symptom of different diseases and health conditions. It can be a normal response to factors such as not getting enough sleep, stress, or eating poorly. When lethargy develops as a response to various life situations, it resolves with rest, increased sleep, good nutrition, and being active. However, in the case of illness, lethargy can linger for days, weeks, or even months. Learn more about the causes, symptoms, and treatments for lethargy. Verywell / JR Bee Symptoms Lethargy has been described as unrelenting exhaustion that includes chronic fatigue, lack of energy, and sluggishness. People who are lethargic may also experience: DepressionApathyLack of motivationMild impairment of alertnessCognitive difficulties (forgetfulness and trouble concentrating)Severe drowsiness Other symptoms that may accompany lethargy include: Aches and pains that won’t go away despite treatmentSleep problemsSensitivity to hot and cold temperaturesEye inflammationChronic fatigue lasting more than two weeksSwollen neck glandsUnexplained weight changesOften feeling sad, empty, or irritable People who are lethargic may act as if they are in a daze. They may not move as quickly as they usually do and may be aware that they are in poor health. Lethargy can be severe enough to affect consciousness. It may cause severe drowsiness—a person can still be alert, but then they drift off either into sleep or into a daze. Causes Lethargy has a number of causes. It can be the body’s response to not getting enough sleep, overexertion, stress, lack of activity, or improper nutrition. It can also be a side effect of medication or the body’s response to alcohol. Consumption of alcohol while on medication can also cause a person to feel lethargic. Lethargy is a symptom of many acute (abrupt onset) conditions, including the flu, stomach viruses, fever, dehydration, and nutritional deficiencies. Other serious medical conditions that cause lethargy may include, but are not limited to: Carbon monoxide poisoning Hyperthyroidism (excess production of thyroid hormone) Hypothyroidism (insufficient production of thyroid hormone) Hydrocephalus (brain swelling) or brain injuries Kidney failure Meningitis Stroke Pituitary diseases (caused by too much or too little pituitary hormone) Adrenal diseases and anemias (due to iron deficiency) Most autoimmune disorders Lethargy is also a symptom of psychological disorders, including major depression and postpartum depression. Seeking Medical Attention Lethargy is rarely a medical emergency. However, it can become one if it is accompanied by other serious symptoms. It is important to seek immediate medical attention and call 911 for sudden energy loss, severe dizziness, chest pain, confusion, blurred vision, high fever, or sudden and severe swelling. Other serious symptoms that require medical attention include: Shortness of breathRapid heart rateAltered consciousnessSevere painSlurred speechFacial paralysisInability to move arms and legsSevere headacheAbdominal painNausea and vomiting Significant changes in behavior with lethargy are concerning and may require medical attention. Seek urgent medical care if lethargy brings about thoughts of self-harm. When lethargy is not a medical emergency, it may still require a practitioner’s visit to determine the cause of it and other symptoms. Lethargy can also affect children and babies. Symptoms needing medical attention in young children and babies include difficulty with waking or appearing to be in a daze, weakness, fevers higher than 102 degrees Fahrenheit, dehydration (including reduced tears, dry mouth, and decreased urine output), rashes, and vomiting. Diagnosis The first step in determining the cause of lethargy is to see a practitioner or get immediate medical attention if necessary. Your healthcare provider will work to determine the cause of lethargy and other symptoms. Diagnostic testing including blood work, urine tests, and imaging may be needed. Once the cause of lethargy can be determined, treatment can begin or a referral to a specialist is made. Your healthcare provider may also recommend seeing a specialist if the cause of lethargy and other symptoms cannot be established. Treatment and prognosis for lethargy will depend on the underlying cause. If lethargy is caused by emotional or physical stress or exhaustion, it does not require medical treatment. It is often resolved by staying hydrated, getting enough sleep, maintaining a healthy diet, and managing stress. Treatment Of course, there are instances in which lethargy will require medical treatment, especially when it is present with other very serious symptoms. In these instances, treatment is aimed at the underlying cause of the lethargy. For instance, treatment of lethargy caused by dehydration is improved intravenous fluids and/or electrolyte consumption. Treatment for hyperthyroidism can resolve lethargy symptoms with anti-thyroid drugs, radioactive iodine, and beta blockers. Fatigue may be a side effect of some of the medications used to treat lethargy, but with time, side effects resolve and lethargy symptoms should as well. Additional examples of treatments for lethargy include: Lethargy associated with inflammation: Treatment includes relieving inflammation with disease-modifying antirheumatic drugs (DMARDs), non-steroidal anti-inflammatory drugs (NSAIDs), and corticosteroids.Lethargy connected to depression: This can be treated by managing depressive symptoms, including with anti-depressants.Cancer-associated lethargy: Healthcare providers may prescribe stimulant medications, such as Provigil (modafinil) for short periods. In addition, Provigil can increase wakefulness. Prescription sleep aids can also be prescribed if sleep issues are causing lethargy. Healthy habits can also help you to manage the fatigue associated with lethargy. This includes staying hydrated, eating healthy foods, reducing stress, being active, and getting plenty of sleep. A Word From Verywell Lethargy is usually not a medical emergency, but it can be a symptom of a serious health condition. Therefore, it is important to seek medical attention as soon as possible. Once the cause of lethargy is determined, it is important to follow the treatment plan prescribed by your healthcaer provider to feel better and reduce your risk for any potential complications. Frequently Asked Questions What does lethargic mean? A person who appears sluggish, has chronic fatigue, and shows a lack of energy is referred to as lethargic. They may also experience depression, a lack of motivation, forgetfulness, difficulty concentrating, drowsiness, and more. What does listless mean? Listless is another way to describe a lack of energy. Listlessness is considered a symptom of lethargy. Should I be concerned about a lethargic baby? Lethargy in a baby is a serious concern. It may be difficult to tell whether a baby is lethargic or just drowsy from sleeping. If they seem less alert, don't smile, are too weak to cry, have difficulty waking up, or show a fever greater than 102 degrees F, they should be immediately brought to a healthcare professional. Was this page helpful? Thanks for your feedback! Losing weight with thyroid disease can be a struggle. Our thyroid-friendly meal plan can help. Sign up and get yours free! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 1 Source Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Seattle Children's Hospital. Emergency symptoms not to miss. Reviewed November 1, 2021. Additional Reading American Addiction Centers. The Effects of Mixing Drugs & Alcohol. American Cancer Society. Managing Cancer-related Fatigue. Cleveland Clinic. Hyperthyroidism. Mayo Clinic. Fatigue. Medline Plus. Dehydration. Seattle Children’s Hospital. Emergency Symptoms Not to Miss. Tindall SC. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Chapter 57 Level of Consciousness.