Malaise and fatigue are common symptoms of a wide-ranging list of ailments. Malaise refers to an overall feeling of discomfort and lack of well-being. Fatigue is extreme tiredness and lack of energy or motivation for everyday activities. More to Know Malaise and fatigue often go hand-in-hand and indicate a person is ill or about to become ill. They can start slowly or appear suddenly depending upon the cause, and can be acute (short-lasting) or chronic (long-lasting). Some common medical problems associated with malaise and fatigue include pneumonia, mononucleosis, the flu, Lyme disease, sleep apnea, blood disorders, congestive heart failure, kidney or liver disease, and diabetes. Psychiatric disorders such as depression and anxiety also can cause malaise and fatigue. Sometimes, malaise and fatigue can be traced to bad health habits and lifestyle factors, including not getting enough sleep, alcohol abuse, an unhealthy diet, caffeine use, and inactivity. Certain medicines also can lead to overtiredness and a general ill feeling. Keep in Mind Malaise and fatigue are common symptoms that can be treated once the cause is known. Because they can indicate a more serious problem, however, anyone experiencing malaise or fatigue that can't be easily explained should see a doctor. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles Mononucleosis (Mono) Mononucleosis - or "mono" - is an infection that causes flu-like symptoms. It usually goes away on its own in a few weeks with the help of plenty of fluids and rest. Read More Chronic Fatigue Syndrome Chronic fatigue syndrome (CFS) is a complicated disease. It's a physical condition that also can also affect a person emotionally. Read More Chronic Fatigue Syndrome Chronic fatigue syndrome (CFS) is a complicated disease for doctors to diagnose — and even fully understand. Find out more about this often misunderstood condition. Read More What's Mono? Kissing is just one of the ways that someone can spread mononucleosis. Most people who get mono are teens or young adults, but kids can get it too. Read More Lupus Lupus is known as an autoimmune disease in which a person's immune system mistakenly works against the body's own tissues. Read More Mononucleosis (Mono) It's sometimes called "the kissing disease," but kissing is just one of the ways that someone can catch mono. Read More Seasonal Affective Disorder Seasonal affective disorder (SAD) is a form of depression that affects some people and appears at the same time each year. Read More Depression Depression is very common. For more information about depression and feeling better, check out this article. Read More Cytomegalovirus (CMV) This virus poses few risks to healthy kids, but can cause serious health problems in unborn babies and kids with a weak immune system. Read More Obstructive Sleep Apnea Brief pauses in breathing during sleep can be normal. But when breathing stops often or for longer periods, it can be a cause for concern. Read More Anemia Anemia is common in teens because they undergo rapid growth spurts, when the body needs more nutrients like iron. Learn about anemia and how it's treated. Read More Anemia Anemia happens when there aren't enough healthy red blood cells in the body. It can be caused by many things, including dietary problems, medical treatments, and inherited conditions. Read More Lyme Disease Lyme disease can affect the skin, joints, nervous system, and other organ systems. If Lyme disease is diagnosed quickly and treated with antibiotics, most people feel better quickly. Read More Lyme Disease The best way to prevent Lyme disease is to prevent tick bites. Find out more about this disease and how to keep those ticks away. Read More Fibromyalgia The chronic condition fibromyalgia causes widespread pain in the muscles, joints, and other areas of the body. Lifestyle changes and other strategies can help kids who have it feel better. Read More Fibromyalgia Fibromyalgia is a long-term condition that causes pain in a person's muscles, joints, and other soft tissues. Find out how doctors tell if a person has fibromyalgia and what can be done to treat it. Read More Lyme Disease Lyme disease can be treated if it's caught early. Find out what causes it, how it's treated, and how to prevent it. Read More What's Anemia? What does it mean when a kid has anemia? Learn about anemia, why kids get it, and how it's treated in our article for kids. Read More The Flu (Influenza) Flu symptoms tend to come on quickly and are worse than the sneezing and stuffiness of a cold. The flu is very contagious. Find out what to do in this article for parents. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.