fatigue symptoms, causes, treatments and all other details


What is Fatigue?

We all experience fatigue for different reasons. So basically, fatigue is a very common individual feeling we experience. In fatigue we experience low energy, exhaustion, sluggishness, etc. Fatigue can be light or even can be extreme physical and mental tiredness.

It is the most common symptom in our daily life. Mostly, with the good amount of rest or with sleep it goes away. But even after taking adequate rest still if you feel tired very frequently, then you need to consider all the clinical reasons that can be responsible for your fatigue!

You will wonder to know tiredness can appear due to silly reasons like lack of proper micro elements. It can appear as the result of any hidden illness in your body including various systemic, neurological, psychiatric conditions!

Yes, fatigue is the initial symptom of any illness in your body. Though in very few cases the exact cause of fatigue can not be identified.

Fatigue definition

Clinically, Fatigue is defined as difficulty in initiating or maintaining willingly (voluntary) mental or physical activities.

Mostly all of us experience fatigue when we become ill for a minor or self-limited infection, so it is a nearly universal symptom. We seek medical help only when the fatigue fails to go away or it appears without a reason (or unknown cause).

Normal fatigue do not need any treatment as it normally goes away with taking rest. But if your fatigue do not go away or becomes severe then it is better to check the cause.

Fatigue Causes

As already mentioned fatigue is a very common symptom of almost all diseases, so here we discussed some major factors causing fatigue.

Health conditions

Different health conditions are one of the most common cause of fatigue in general population. If you feel tired check if you have common health issues like Anaemia, Sleep disorders, Arthritis, Diabetes, Eating disorders, Thyroid disorders like Hypothyroidism (underactive thyroid), Cancer, Kidney diseases, Liver diseases, Lung diseases, Heart diseases, etc.

Even uncommon diseases like autoimmune disorder, chronic fatigue syndrome, fibromyalgia, celiac disease, inflammatory bowel disease, multiple sclerosis, chronic pain, etc. can also give tiredness and appear with a fatigue symptom. In fact there is a disease chronic fatigue syndrome where fatigue never goes away, but that is rare.

Lifestyle factors

In todays life, life style is a huge factor for fatigue. Due to our lifestyle we are more prone to fatigue. As it is commonly known that prolonged intense physical or mental activity makes our body tired and gives fatigue. But do you know people who are physically inactive faces fatigue more due to physical inactivity?! Yes, it is true. So your lifestyle plays a vital role in your fatigue.

Mental condition

For a very large number of people fatigue occurs due to their emotional state of mind. Yes, our mental stress, anxiety, depression, boredom or any life event that gives stress creates fatigue and we feel tired. All these emotional stress gives lack of sleep that ends up giving fatigue too. It is always advised to solve sleep difficulty as soon as possible.

Hormonal imbalance

Hormonal imbalance is a big cause of fatigue especially in women. Certainly women feels fatigue in the specific time frame of their hormonal cycle. Also hormonal contraception (birth control pills and implant) causes fatigue.

But overall many times in regular cases both men and women faces fatigue due to the hormonal imbalance. Hormonal imbalance causes metabolic imbalance and electrolyte imbalance in body that leads to fatigue.

Few hormonal diseases like cushing syndrome, Additions disease etc. causes fatigue too.

Drug intake

Many times your medicines are the reason of your fatigue. Certain medications such as antidepressants, sedatives, anxiety medications, antihistamines, steroids, etc. creates fatigue.

Only controlled usage of these drugs can remove the problem. In opposite, abrupt withdrawal of medicine and change of dose may also lead to fatigue.

Similarly treatments like Chemotherapy, radiation therapy, etc. causes fatigue.


Malnutrition is a very common cause of fatigue. Mineral and vitamin deficiency causes fatigue. Many microelements like zinc, copper, etc. in our body have impact to stay us fit and energetic. When due to malnutrition these elements lack in our body, fatigue appears. Only a balanced diet can solve the issue.

Addiction pattern

People have different addictions like alcohol, coffee, nicotine, etc. When these additions are little it is ok. But when your addictions are uncontrolled, it creates health issues like fatigue. You will surprised to know, even long hours video game addictions can lead to fatigue.


Any kind of viral infections makes us weak and tired. Viral infections such as flu, covid 19, EBV, human herpes virus 6, cytomegalovirus, HIV, infectious mononucleosis, hepatitis cause fatigue. Malaria, tuberculosis, pneumonia, etc. also lead to fatigue.

The possible reasons behind your fatigue

Fatigue is a very common symptom for various diseases. So apparently it is difficult to know the reason behind your fatigue. When fatigue appears you should consider all the possible causes that can make fatigue. Here is the list of possible reasons (also known as differential diagnosis) of fatigue


Any infection in your body, be it acute or chronic causes fatigue. In fact for viral infections fatigue stays for long time even after the infection recovers. A great example of viral infection causing fatigue is the fatigue among corona infected patients. Even after recovery from covid 19, fatigue stays for long time.

So it is important to evaluate unexplained fatigue as a cause of undiagnosed infection. In case of prolonged or chronic fatigue, proper history, physical examination, risk factors for infections particularly for tuberculosis, HIV, chronic hepatitis, endocarditis needs proper evaluation.

Infectious mononucleosis may cause prolonged fatigue. This fatigue persists for weeks to months after the acute illness.

Sleep disorders:

Many of us face sleeping issues, sometimes it is occasional and sometimes it stays for long days. In both cases fatigue appears. When the lack of sleep is due to other reasons like due to stress, then the fatigue appears more.

When lack of sleep persists for a longer period of time then taking adequate rest can usually resolve the issue. If not, then the cause of fatigue might be different. Actually different medical conditions causes lack of sleep. So when taking adequate sleep fails to resolve your fatigue then your fatigue is not because of sleep issues. It needs further checks.

Lack of sleep due to other disorders like obstructions in our breathing passage cause fatigue that is more severe. Obstructive sleep apnoea is an important cause of excessive daytime sleepiness with fatigue. It should be investigated by overnight polysomnography especially in those with prominent snoring, obesity, or other symptoms of obstructive sleep apnoea.


As mentioned above, fatigue can be seen due to malnutrition. Here you should remember, it does not matter how much you eat but the matter is how balanced and nutritious food you take everyday. Only protein stuffed diets are not enough. Eating adequate fruits, vegetables are very important to take. The main aim is to maintain all the micro elements, minerals, vitamins etc. in a good range within your body.

Because lack of elements like Vitamin D, Sodium, Zinc etc. causes fatigue. So taking them naturally through food is vital.

Blood disorders:

Anemia is a very common cause of fatigue particularly in women. Very commonly, fatigue may be associated with chronic or progressive anemia. To check if you have anemia check if there is increased heart rate and breathlessness during heavy work, irregular periods etc. Anemia may also lead to fatigue in other chronic illnesses.

Not only anemia, any blood disorder causes fatigue. Low serum ferritin in the absence of anaemia may cause fatigue, but with iron replacement, in this case, fatigue normally goes away.

Physical inactivity:

Physical inactivity can cause fatigue. Many times we experience fatigue after long physically inactive days. How do you know if your fatigue is due to physical inactivity? Simple, if you feel tired couple of days after physical inactivity and if your fatigue improves after you do some physical works such as brisk walking, jogging, cycling, etc. then your fatigue is most commonly due to physical inactivity. In fact many sufferers of fatigue find an improvement after increasing their physical activity.


Fatigue is commonly present in women at all stages during their pregnancy and after delivery (postpartum). So if you are pregnant and experiencing fatigue, then the most likely cause of fatigue in your case is pregnancy.

Hormonal disorders:

Sometimes fatigue with true muscle weakness may be a symptom of hypothyroidism, particularly if there is hair loss, dry skin, cold intolerance, constipation, weight gain, etc. These symptoms are commonly seen in hypothyroidism. So if you have fatigue with all these symptoms then most likely cause of fatigue in your case is hypothyroidism. Also if your fatigue is present with heat intolerance, sweating, and palpitations, then the most likely cause of fatigue is hyperthyroidism.

Adrenal insufficiency may cause unexplained fatigue as a prominent symptom. Sometimes it is associated with decreased appetite (anorexia), weight loss, nausea, muscle pain (myalgia), joint pain (arthralgias). Hyperpigmentation (increased pigmentation of skin that is darker in color) may also be present. If you have these symptoms along with fatigue then the most likely cause of your fatigue is adrenal insuffiency.

Low sodium in the blood (hyponatremia), higher than normal potassium in the blood (hyperkalemia) may be present in adrenal insufficiency. But electrolyte tests (sodium, potassium, etc.) need to be done to confirm if you have any abnormality of these electrolytes ( sodium, potassium, etc.) in your body.

A high level of calcium in the blood (mild hypercalcemia) can cause fatigue (this may be vague). Very high level of calcium in the blood (severe hypercalcemia) can cause lethargy, unconsciousness, or coma. Here also you need to do your electrolyte test for calcium, only then you can say if you have abnormal levels of calcium in your blood.

Glucose deficiency in blood (hypoglycemia) and excess glucose in the blood (hyperglycemia) can cause lethargy, sometimes associated with confusion. Diabetes Mellitus, mainly type 1 diabetes can cause fatigue not associated with glucose level. If you are a known patient of diabetes then fatigue in your case can be due to diabetes. Proper control of diabetes usually resolves fatigue.

If your fatigue is due to lower levels of glucose in your blood then taking glucose as supplement or taking any sweet drink such as fruit juice, etc. can improve your fatigue. Specially if you are medicine dependent for diabetes and have not taken food for more than 2 hours then hypoglycemia can be a possible cause of fatigue for you. Hypoglycemia can be life threatening, so drink sweet drink immediately.

Fatigue may also be seen in different hormonal diseases like Cushing’s disease, hypoaldosteronism and hypogonadism.

Liver and kidney diseases:

Chronic liver failure can cause fatigue.

Also, chronic kidney disease can be a cause of fatigue. Over 80 percent of hemodialysis patients complain to have fatigue, so it is one of the most common symptoms in chronic kidney disease sufferers.

Heart and blood vessel (Cardiovascular) diseases:

Fatigue is the most preliminary symptom of any heart disease so an early evaluation can prevent heart issues. If you have a family history of heart issues then you should never ignore fatigue. Fatigue is the most common symptom in congestive heart failure.

Lung (Pulmonary) diseases:

For chronic obstructive pulmonary disease fatigue is most common. For other lung diseases like bronchitis, asthma etc. fatigue persists. So the cause should be evaluated early.

It is important to mention, in both heart and lung diseases fatigue appears in the most early stage so you should not ignore.

Systemic inflammatory disorders/ Joint, muscle, bone disorders or rheumatologic disorders:

Fatigue is common in chronic inflammatory disorders such as systemic lupus erythematosus, polymyalgia rheumatica, rheumatoid arthritis, inflammatory bowel disease, anti neutrophil cytoplasmic antibody (ANCA) – associated vasculitis, sarcoidosis, and Sjogren syndrome. But here fatigue is not the only symptom. In primary immunodeficiency diseases, fatigue is also present.


Medicines that more likely cause fatigue are antidepressants, antipsychotics, anxiolytics, opiates, antispasticity agents, antiseizure agents, beta blockers.

Drug withdrawal and chronic alcohol use can also cause fatigue.


Obesity can cause fatigue. Also, physical inactivity, diabetes, depression that are commonly associated with obesity may be a contributor for the development of fatigue in these patients.

Neurological causes (Diseases of Nerve):

For those who are suffering from fatigue, many of them complain that they are feeling weak. In these sufferers, careful muscle examination of the body shows no muscle weakness.

But if muscle weakness is found, then further follow up is needed. Fatigue due to muscle weakness is seen in neuromuscular disorders such as myasthenia gravis.

Fatigue is also the most common symptom in multiple sclerosis, fatigue occurs in more than 90 percent of sufferers in multiple sclerosis. Fatigue is also seen in the sufferer of many neurodegenerative diseases such as parkinson’s disease, central dysautonomias, amyotrophic lateral sclerosis, etc.

Fatigue is also common after stroke, but what is the cause of fatigue after stroke is poorly understood. Episodic fatigue may be a premonitory symptom ( the symptom tells us that something bad or more serious is likely to happen) of migraine. Fatigue may also be the result of traumatic brain injury, depression, or sleep disorder.

Psychiatric illness:

Fatigue is a common symptom of many major psychiatric problems such as depression, anxiety, etc. It is seen that more than three quarters of unexplained chronic fatigue sufferers reported psychiatric symptoms.

Also, for sufferers with any neurological problems or systemic problems (that affects the entire body), fatigue is an independent symptom of those diseases, but in comorbid psychiatric symptoms that is when more than one psychiatric symptoms are present, they also play a vital role for the development of fatigue.

Cancer (Malignancy):

Fatigue with unexplained weight loss can be a sign of hidden cancer (malignancy). But, indeed, cancer is rarely found in those sufferers of unexplained chronic fatigue where other telltale signs or symptoms are absent.

Cancer related fatigue is experienced by 40 percent of sufferers at the time of diagnosis and more than 80 percent of sufferers at some time in the course of the disease.

Disorders of unclear cause:

There are few rare disorders that causes fatigue but the reasons are not known yet. Example- Gulf War syndrome, chronic fatigue syndrome and fibromyalgia.

Fatigue Symptoms

Symptoms of fatigues are commonly shown as

  1. drowsiness all day long.
  2. extreme exhaustion
  3. Lack of concentration or difficulty in learning new skills.
  4. Headache
  5. Vision problems (example blurred vision)
  6. Lack of motivation 
  7. Sore muscles
  8. Irritability
  9. Bloating,constipation,diarrhea, etc. gastrointestinal symptoms.
  10. Disturbed sleep.
  11. Appetite loss 
  12. Slowed reflexes and response

Fatigue Diagnosis

Although any layman can even understand that it is fatigue, but still a proper diagnosis is needed to find out the root cause. Because only then you can get relief from fatigue permanently.

  • Detailed medical history about the quality of fatigue, pattern of fatigue, duration of fatigue, associated symptoms, alleviating factors – are important to know as this helps to further evaluation and treatment.
  • Also, it is important to confirm if the fatigue is acute or chronic, if the fatigue is due to primarily mental, physical, or a combination of both.
  • Physical examination helps to distinguish fatigue from excessive sleepiness, shortness of breath during heavy work , exercise intolerance, or muscle weakness.
  • The presence of fever, chills, night sweats, weight loss indicates that probably a hidden infection or malignancy is present.
  • History of prescription drugs, over-the-counter drugs, herbal drugs, recreational drugs, and alcohol use is very important.
  • Circumstances associated with the initiation of symptoms and any potential triggers are very important to know.
  • Social history such as life stressors, work hours, social support network, domestic affairs, the violence of partner, etc. is important to know.
  • Sleep habits and sleep patterns are also important to know.
  • The impact of fatigue on daily functioning is important to know.
  • Physical examination is needed. Physical examination is based on medical history. A mental status examination is also needed, particularly for the symptoms of depression and anxiety. Neurological examination is needed to know if muscle weakness is present.
  • If the physical examination can not determine if muscle weakness is present or not then electromyography with nerve conduction studies is a helpful test.
  • General physical examination should screen for signs of cardiopulmonary ( heart and lung) disease, malignancy,  lymph node enlargement (lymphadenopathy), organ enlargement (organomegaly), infection, liver failure, kidney disease, malnutrition, endocrine ( hormonal) abnormalities, connective tissue disease.
  • If the sufferer has widespread muscle pain, then assessment of tender points may help to know if fibromyalgia is present or not.

Fatigue diagnostic test

Laboratory testing helps to identify the cause of chronic fatigue in 5 percent of cases. Medical history and physical examination determine which laboratory test is needed. Normally the following tests are done

  1. Complete blood count, differential count ( to screen for anemia, infection, or malignancy) test
  2. Electrolytes ( sodium, potassium, calcium) test
  3. Glucose test
  4. Renal function test
  5. Liver function test
  6. Thyroid function test
  7. Test for HIV
  8. Adrenal function test
  9. Erythrocyte sedimentation rate (ESR) test

Here it is important to mention, whole body imaging scanning is usually not needed.

Fatigue Treatment

The main treatment priority is to address the underlying medical condition that is responsible for fatigue. Sometimes the underlying medical conditions are get cured and sometimes they are persistent.

Antidepressant treatment is helpful in chronic fatigue treatment if symptoms of depression are present.

But antidepressants can also cause fatigue, so if they are not clearly effective then discontinuation of antidepressants is needed.

In chronic fatigue syndrome and cancer-associated fatigue, cognitive behavioral therapy is helpful.

In chronic fatigue, cognitive behavioral therapy and graded exercise are helpful. Here physical exercise mostly walking is gradually increased with attention to target heart rates to avoid over exertion.

Psychostimulants such as amphetamines, modafinil, armodafinil help to increase alertness and concentration. They reduce excessive daytime sleepiness in some medical conditions, so maybe helpful for fatigue in these sufferers.

But these drugs are not effective to treat fatigue in case of post-traumatic brain injury, parkinson’s disease, cancer, and MS.

For sufferers with low vitamin D status, vitamin D replacement leads to improvement of fatigue.

Chronic Fatigue

When your fatigue is acute then it needs medical evaluation because mostly it gives an identifiable medical cause other than unexplained chronic fatigue. For acute fatigue, proper treatment in timely manner can prevent it to become chronic. In the evaluation of chronic fatigue most common cause is psychological conditions and even in many cases there is no identifiable cause, so they are unexplained. Unexplained chronic fatigue does not go away completely, but symptomatic treatment can improve the quality of life in these cases.


Fatigue is a very common symptom that mostly occurs due to today’s stressful lifestyle. It needs special attention only when it occurs more frequently. The medical evaluation is needed in such frequent occurrence because fatigue is the alarm from your body that everything is not well in your body. So it is better to find the cause and remove it. Stay healthy and happy.


  1. Harrison’s Principles of Internal Medicine 20th edition, (pg.132 to pg.135)
  2. Centers for Disease Control and Prevention
  3. NHS, UK
  4. Davidson’s Principles and Practice of Medicine 23rd edition (page 589 to 595)

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