If you have a sense of malaise, you may not feel quite right, but you might be hard-pressed to put your fingers on exactly what’s bothering you. It’s not a condition, but a set of symptoms linked to some other problem. When you’re in the grip of it, you might have fatigue, pain, and a lack of interest in your usual activities.

Depending on the cause, malaise can start slowly or hit you suddenly.

Scores of illnesses or disorders can lead to different degrees of malaise. They may range from viral conditions and blood diseases to organ failure and psychiatric disorders.

Short-Term (Acute) Illnesses

A sudden infection that eventually runs its course can shock your body. There are several diseases that are more closely linked with malaise. The most common ones and their symptoms — in addition to malaise — include:

Acute bronchitis or pneumonia. If you have this chest infection, you might have fever, chills, cough, and chest pain.

Mononucleosis (“mono”). If mono is the cause of your malaise, you could have a sore throat, headache, and swollen tonsils and lymph nodes.

Flu. If you have this virus, you might have a fever, cough, sore throat, runny nose, and body aches.

Lyme disease. It’s an infection that comes from a tick bite. You could have a rash, achy or swollen joints, night sweats, and be sensitive to light.

Hepatitis. If you have this liver disease, you might feel flu-like symptoms and have belly pain, dark urine, and pale stools.

Fibromyalgia. With this condition, you’ll have joint pain and tenderness, sleep problems, trouble concentrating, and morning stiffness.

Long-Term (Chronic) Illnesses

Malaise can be an early sign or ongoing symptom of long-term illnesses like:

Kidney disease. If this is the cause of your malaise, you could also have nausea and muscle cramps. You might vomit and not have much of an appetite.

Severe anemia. If you have this blood disorder that comes from low iron, you could feel dizzy and have pale skin, leg cramps, and a fast heartbeat.

Diabetes. If this is what’s behind your malaise, you might feel very thirsty or hungry. You could have a dry mouth and blurred vision and need to pee more often than usual.