Merck Manual

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Some Common Causes and Features of Involuntary Weight Loss

Some Common Causes and Features of Involuntary Weight Loss


Common Features*


Abdominal pain, fatigue, abnormal areas of skin darkening, and light-headedness

Blood tests

History of excessive alcohol consumption

In men, feminization, with loss of muscle tissue, decrease in armpit hair, smooth skin, breast growth

In men and women, sometimes a distended abdomen due to fluid (ascites) and small purple spots on the skin (spider angiomas)

A doctor's examination

Sometimes liver tests and/or liver biopsy

Inappropriate fear of weight gain in an emaciated young woman or adolescent female and lack of normal periods

Only a doctor's examination

Often night sweats, fatigue, and fever

Sometimes bone pain at night or other organ-specific symptoms

Organ-specific evaluation

Sadness, fatigue, loss of sexual desire and/or pleasure, and sleep disturbance

Only a doctor's examination

Increased appetite

Excessive thirst and increased urination

Measurement of the amount of sugar (glucose) in the blood


History of use

A doctor's examination

Sometimes stopping the drug

Fever, night sweats, fatigue, cough, and shortness of breath

Often a history of living in or visiting an area where a specific fungus is common

Usually cultures and stains

Sometimes blood tests

Sometimes biopsy

Headache, muscle pains, jaw pain when chewing, fever, and/or visual disturbances in a person over 50

Blood tests

Sometimes temporal artery biopsy

Worm infections in the digestive tract

Fever, abdominal pain, bloating, flatulence, and diarrhea

Usually residence in or travel to developing countries

Microscopic examination of stool

Fever, shortness of breath, cough, swollen lymph nodes throughout the body, diarrhea, and fungal infections

Blood tests

Kidney disease

Limb swelling, fatigue, itching, and sometimes frothy urine

Blood tests and urine tests

Usually risk factors (for example, cranial nerve dysfunction, use of certain drugs, and aging)

Only a doctor's examination

Diarrhea, flatulence, and sometimes greasy or oily stools

Stool testing

Dental problems

Tooth or gum pain

Bad breath, gum disease, and missing and/or decayed teeth

Only a doctor's examination

Cough and shortness of breath

Fever, fatigue, and swelling of lymph nodes throughout the body

Chest x-ray

Sometimes chest CT


Fever, night sweats, joint pain, shortness of breath, and fatigue

Often in people with heart valve disorders or who inject drugs intravenously

Blood cultures


Increased appetite

Heat intolerance, sweating, tremor, anxiety, rapid heart beat, and diarrhea

Blood tests to evaluate thyroid function

Fever, night sweats, cough, and coughing up blood

Sometimes risk factors (for example, exposure to people with tuberculosis or residence in poor living conditions)

Sputum culture and smear

* Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present.

CT = computed tomography; HIV = human immunodeficiency virus; NSAIDs = nonsteroidal anti-inflammatory drugs, OTC = over-the-counter; SSRIs = selective serotonin reuptake inhibitors.