The causes of weakness and fatigue near the end of life are not always known. Often there are multiple causes. Common causes include:
- medicines such as opioids, benzodiazepines or tricyclic antidepressants
- infection
- sleep disturbances
- symptoms due to illness such as pain, nausea and vomiting or constipation
- treatment such as radiotherapy, chemotherapy or surgery
- metabolic disturbances such as high blood calcium, high blood sugar, low potassium, high sodium, low magnesium, low blood count (anaemia), renal failure, liver failure and dehydration
- poor nutrition
- emotional causes such as depression, anxiety, stress
- weight loss due to illness (cachexia) or loss of appetite
- other accompanying illnesses such as cancer, heart disease, liver disease, thyroid disease and motor neurone disease.