Causes of Chronic Fatigue
Many Illnesses and even Medications Can Cause Persistent Fatigue
Aug 14, 2008
Many people hesitate to see a doctor because of fatigue, as they feel it is a sign of weakness. However, if fatigue persists beyond several weeks, medical help should be sought. The cause could be an easily treatable condition - or even something serious. Sometimes reducing one's working hours and/or other responsibilities may solve the problem.
Conditions Causing Fatigue
This is far from a complete list - almost any medical condition can cause fatigue, but usually there are other symptoms as well.
- adrenal insufficiency
- anemia
- deficiency of some B complex vitamins
- multiple sclerosis, systemic lupus erythematosus (SLE) and many other autoimmune diseases
- depression
- hypothyroidism
- sleep disorders like sleep apnea
- stress/burnout
- cancer
- allergies
- glandular fever (mononucleosis) - the fatigue can persist for up to six months afterwards
- fibromyalgia
- chronic sinusitis
- pregnancy
- mitochondrial diseases
- reactive hypoglycemia
- joint hypermobility
- diabetes (both types)
- dysautonomia
Different illnesses cause different kinds of fatigue. For example depression and adrenal problems tend to make you lethargic, but some other conditions would mostly affect your physical endurance.
There are often complex relationships between these causes. Fatigue can cause depression and vice versa. Joint hypermobility often causes fatigue, but it is also a risk factor for CFS/ME.
Medications
Medications can also cause exhaustion and tiredness. Some of them are used for this reason as sleep aids, but often the fatigue can persist until the next day, or even longer. Common culprits include
- psychiatric drugs, especially antipsychotic drugs and tricyclic antidepressants
- benzodiazepines and other tranquilizers
- sleep aids
- anticonvulsants (epilepsy drugs)
- antihistamines
- muscle relaxants
- narcotic painkillers (opioids)
- cancer chemotherapy
Which medications cause fatigue is highly individual - almost any drug can be the culprit. NSAIDs and even stimulants are sedating to some people. With some medications, especially antipsychotic drugs, the fatigue can be delayed by weeks after starting the drug, making it difficult to see a connection.
As is evident, sometimes it's difficult to decipher the cause of the fatigue. Both depression and some antidepressants can cause fatigue. Allergies and the antihistamines used to treat them can both lead to fatigue.
Often the problem can be solved by reducing the dose or changing to a different drug in the same class, especially with psychiatric drugs and anticonvulsants.
Fatigue in CFS/ME
The fatigue in CFS/ME can be continuous or intermittent, but it is always associated with post-exertional malaise (feeling ill after exercise or other excessive activity), which can last for several days or even weeks. Sometimes it is delayed by more than 24 hours.
In CFS/ME there are always other symptoms besides fatigue, such as pain, headaches, swollen glands, fever, cognitive problems, nausea, stomach upset, cardiac symptoms and dizziness. Fatigue alone is not indicative of this illness.
The fatigue in CFS/ME is often called "medically unexplained", but this is misleading considering the profound organic changes in brain metabolism found with brain imaging studies, especially SPECT scans. Often there are also structural changes visible in MRI pictures.
Chronic Idiopathic Fatigue
Chronic idiopathic fatigue refers to persistent fatigue whose cause could not be found despite thorough examination. The cause could be a rare illness yet to be identified or a mild variant of a common illness, such as atypical multiple sclerosis.
Lifestyle modifications - eating well, sleeping enough, meditation, exercise, and stress reduction - may relieve chronic fatigue. Large doses of vitamin B12 are often helpful. Severe cases can be treated with stimulant drugs, such as modafinil (Provigil).
References
Nijs J, Aerts A, De Meirleir K. Generalized joint hypermobility is more common in chronic fatigue syndrome than in healthy control subjects. J Manipulative Physiol Ther. 2006 Jan;29(1):32-9.
Ellis FR, Nasser S. A pilot study of vitamin B12 in the treatment of tiredness. Br J Nutr. 1973;30:277-83.
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