10 medical reasons for feeling tired

Any serious illness, especially painful ones, can make you tired. But some quite minor illnesses can also leave you feeling washed out. Here are 10 health conditions that are known to cause fatigue.

Sick or tired?

If you’re getting your eight hours of sleep a night but still feel exhausted, it’s time to see a doctor.

It’s also worth seeking medical advice if you have any of these symptoms:

  • confusion
  • dizziness
  • blurred vision
  • unexplained weight loss or gain
  • swelling
  • constipation
  • insomnia
  • depression 
  • headaches

1. Coeliac disease

This is a type of food intolerance, where your body reacts badly when you eat gluten a substance found in bread, cakes and cereals. One in 100 people in the UK are affected, but research suggests that up to 90% of them don’t know they have the condition, according to patient group Coeliac UK. Other symptoms of coeliac disease, apart from tiredness, are diarrhoea, anaemia and weight loss. Your GP can check if you have coeliac disease through a blood test.

Read more about coeliac disease.

2. Anaemia

One of the most common medical reasons for feeling constantly run down is iron deficiency anaemia. It affects around one in 20 men and post-menopausal women, but may be even more common in women who are still having periods.

Typically, you’ll feel you can’t be bothered to do anything, your muscles will feel heavy and you’ll get tired very quickly. Women with heavy periods and pregnant women are especially prone to anaemia.

Read more about iron deficiency anaemia.

3. Chronic fatigue syndrome

Chronic fatigue syndrome (also called myalgic encephalomyelitis or ME) is a severe and disabling tiredness that goes on for at least six months. There are usually other symptoms, such as a sore throat, muscle or joint pain and headache.

Read more about chronic fatigue syndrome.

4. Sleep apnoea

Sleep apnoea is a condition where your throat narrows or closes during sleep and repeatedly interrupts your breathing. This results in bad snoring and a drop in your blood's oxygen levels. The difficulty in breathing means that you wake up often in the night, and feel exhausted the next day.

It’s most common in overweight, middle-aged men. Drinking alcohol and smoking makes it worse.

Read more about sleep apnoea.

5. Underactive thyroid

An underactive thyroid gland means that you have too little thyroid hormone (thyroxine) in your body. This makes you feel tired. You’re also likely to put on weight and have aching muscles. It’s most common in women, and it happens more often as you get older.

Your GP can diagnose an underactive thyroid by taking a blood test.

Read more about having an underactive thyroid.

6. Diabetes

One of the main symptoms of diabetes, a long-term condition caused by too much sugar in the blood, is feeling very tired. The other key symptoms are feeling very thirsty, going to the toilet a lot and weight loss. Your GP can diagnose diabetes with a blood test.

Read more about diabetes and find out how to make smart sugar swaps.

Find your local diabetes support services.

7. Glandular fever

Glandular fever is a common viral infection that causes fatigue, along with fever, sore throat and swollen glands. Most cases happen in teenagers and young adults. Symptoms usually clear up within four to six weeks, but the fatigue can linger for several more months.

Read more about glandular fever.

8. Depression

As well as making you feel very sad, depression can also make you feel drained of energy. It can stop you falling asleep or cause you to wake up early in the morning, which makes you feel more tired during the day.

Read more about depression.

Find your local depression support services and your local depression self-help groups.

9. Restless legs

This is when you get uncomfortable sensations in your legs, which keep you awake at night. You might have an overwhelming urge to keep moving your legs, a deep ache in your legs, or your legs might jerk spontaneously through the night. Whatever your symptoms, your sleep will be disrupted and of poor quality, so you’ll feel very tired throughout the day.

Read more about restless legs.

10. Anxiety

Feeling anxious is sometimes perfectly normal. However, some people have constant, uncontrollable feelings of anxiety, which are so strong they affect their daily life. Doctors call this generalised anxiety disorder (GAD). It affects around around one in 20 people in the UK. As well as feeling worried and irritable, people with GAD often feel tired.

Read more about anxiety.

Find your local anxiety support services.

Glandular fever

An expert explains how glandular fever is caused, how it's passed on and how to recognise the symptoms.

Media last reviewed: 29/05/2015

Next review due: 29/05/2017

Page last reviewed: 21/02/2015

Next review due: 21/02/2017


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The 22 comments posted are personal views. Any information they give has not been checked and may not be accurate.

crackersgem said on 30 July 2015

What about fibromyalgia?

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YOUANDME1 said on 18 November 2014

To Moody Cat,,
Sorry you are suffering so. Me, too. Rght in the same boat.

Terrible debilitating fatigue. Monstrous.

Right now I am in America. Do not be fooled into thinking we have it better. I spent the night in the ER over the weekend with terrible symptoms, scary symptoms, real symptoms, incluidng dizziness. lightheadedness, a deep down not okay something is WRONG feeling including chills w no fever ( odd) nausea, pale grey complexion and a history of AFIB, CHF AND two heart related hospitalizations and so naturally I was concerned it could be life threateneing. And they sent me home without properly looking into my heart, ,arteries, etc.
And I am STILL feeling lousy with buzzing in my head all te time and pale and very wobbly.

So we are just as lame over here,if not moreso.
We must not give up! But do not rely on the NHS to cure you. You must be your own health advocate. Which feels impossible, I know, given your condition.
What are the emotional wounds that need addressing.? I know mine. The body always follows the mind, no exceptions!
Read Eckhart Tolle on The Pain Body.

Well, we are still living in the Neanderthal Age when it comes to medicine.
Edgar.Cayce had the right idea in 1928.

Feel free to write to me here anytime. People who are suffeirng need MORE LOVE, EXTRA LOVE, ENCOURAGEMENT AND SUPPORT!

Peaceful healing wishes and my heart goes out to you.
You are not Alone.

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A once happy girl said on 24 June 2014

I had a diagnostic laparoscopy done in March 2014 for unexplained infertility. They found nothing apart from very minor endometriosis. I was very scared to do this op (as it was the first) but assures myself that I would get an answer for my infertility and would have better chance for a baby which I am trying since three years. I have not been in pain and the operation has well BUT we are nearly July and I have been feeling constantly tired and drained out after this operation. I was given only one week of rest and has to resume duty afterwards. Its so hard to turn from a very healthy and active person to a lethargic human being. My body feel so tired and my arms and feet are so week. My doctor just doesn't want to associate this with the operation and maybe he thinks that I am pretending all this or maybe its anxiety. I have stop seeing him. well dear doctor, it happens just after I went through the general anesthesia and operation. Before that i as avery happy and healthy person! Just want to knw what is happening to my body and when I fele my normal me again!

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Olga123 said on 14 May 2014

A response to Moody_Cat. I fought fatigue for the last 8 years - 7 years I trusted NHS doctors who could not address it at all and then I went to my country where I was diagnosed with a gut dysbiosis, in short an imbalance of good and bad bacteria in my gut. I am currently talking Mutaflor and Bio- Kult and feeling great. I was deficient in good bacteria called e-coli. Bio-kult provides me with the rest essential good bacteria. Do the tests and then go from there. ask pharmacists if Bio-kult is good for you.You may need to do a food intolerance test . Ask your GP for a referral to a dietician. You may be deficient in magnesium if your muscles ache. Good luck!

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Moodys_Cat said on 16 April 2014

I ended up viewing this site as I am absolutely desperate to find a cure to the hourly fatigue & exhaustion I experience since receiving an organ transplant back in 2005

I remember so well how this first started.

Like a bad hangover fog I now live with this day in, day out

Like living 24/7 without sleep. Never feeling refreshed, always feeling feverish, grey and achy, and yet even on the warmest days, still feeling cold & chilly.

The exhaustion never ever stops. Some days it is so hard to lift my head from the pillow. I sleep for hours, but never awake feeling really alert & well.

When I eat, I often collapse soon after. I try to narrow down trigger foods which may cause this without success

Every day I grow weaker and weaker. Exercise is now impossible. Even getting from room to room takes every ounce of strength

And all of the above combined with such joint aches and pain, and the most debilitating adrenaline rush.

Nearly ten years of this. With what help? What tests?

Where is the NHS service we are told exists or the doctors who purport to care.

Perhaps if we, the patients were treated as individuals searching for a cure rather than a statistic at a doctors surgery we may have found a reason for this disease years ago.

Instead, people such as myself search the internet for some clue as to this terrible debilitating condition & try to tell GP's who listen with half an ear and one eye on the clock.

If this were America, France, Belgium or Germany this sub-standard of health care would not be tolerated, but here in England, because it is the NHS,we the patients have to endure this and be grateful.

If the cause of this disease is any of the above, I want to know.

Don't I have a right to know?

An equal right to have my healthcare taken as seriously within the NHS system as anyone who can afford to pay for private treatment?

Is that really too much to ask?

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RomeoG said on 05 March 2014

I had swine flu in 2011 when I was 19 and I never felt anything like it before when i got well again from reviving at home, weeks later I felt so drained all the time and could sleep alday and then all night
My muscles felt weak and my energy effected my everyday things like football which I had to quit and college and even trying to go out for walks my energy would just drop and I'll go pale

I started getting huge bruises on the backs of my legs so I went Gp and I was tested for cancer, it wasn't cancer so I was tested for ME and it wasn't that, I had all this for a year and a half and I've never found out what it was
I'm so much better then before but I still sometimes have my fugitive days even if I've slept well

any ideas what this could be as I'm now 22

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Faisal Bangash said on 16 December 2013

Hi There :-
Its good to hear and learn about the said issue from NHS. I want to tell my problem too, For some years i am facing issue like this tiredness, when i even run for 10 to 20 meters , i fell like i have climbed a high mountain, i take big breaths to calm my self and some times i fell out of breath, i am posting this so that someone can help me out, i don,t have any disease and my cholesterol level is ok too......

Thanks and take care

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YoMo23 said on 12 October 2013

I desperately need advice/help. My son was diagnosed with Stage 3 Cancer at 18 years and had his bowel removed as a consequence. During surgery they pierced his small intestine and sewed him up unaware of the problem. He was then asked to start consuming food. As a result peritonitis set in and he had further two surgeries to rectify the issue. He since has had Thyroid problems and acute Vitamin B deficiency. He is chronically tired and I do not know what to do to help. Can someone please give me some advice. The doctors don't seem to be able to offer any solution. He is now 25 years and I find it hard to watch him not enjoy life.

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triple EEE said on 02 July 2013

Since my early twenties ive felt constantly fatigued. Was diagnosed with low vitamin d3. Currently taking shots for d3 deficiency spaced 21 days apart. Evn after my 2nd shot so far feel constantly fatigued. Gained alot of weight the past year. Cant seem to understand the cause either of the weight gain or the fatigue. TSH levels are normal.

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Redirish said on 19 June 2013

I have struggled for 16 years with fatigue, swollen joints, disfunctunal hands and limbs a times...left a number of jobs, slept threw most of those 16 years. Wasn't till recently they finically had enough to go on and diagnosed me with mixed connective tissue disease. A mixture of overlapping illnesses all with different symptoms which caused an issue when trying to diagnose. Many, many doctors, referrals to and from an finically one doctor diagnosed after two years of following my symptoms and blood work. SLE (lupus), rhueumatoid arthritis,reynaulds syndrome and fibromyalgia was the cause of what I thought for yrs was all in my head. That dr recently told me that she can't do anything about the fatigue, and is only treating the lupus part as it is showing more signs then the other diseases. If it wasn't for the fatigue, I would be able to handle the chey limbs, and swelling with shortness of breath. I feel like my life is gone, I'm not working and last week of EI is next week! While I patiently wait for a decision from CPP. I had 3 jobs for the longest time, and I was an oddly strong female muscular wise, and now, I can't wait for kids to go to school in morning and I go right back to bed. The medications she gave me also add to the fatigue and I'm paying now but I quit ALL of them except my inhaler. Please, if anyone out there can give me an idea, I'd be in ur debt. I would look at the narcolepsy that was mentioned above, although yet another disease is just not what I'm looking for. Please help!

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deleybear said on 05 June 2013

I'm under investigation for 'Idiopathic Hypersomnia' - idiopathic = they don't know the cause, hypersomnia = long sleep time (10+ hours) with excessive daytime sleepiness and feeling unrefreshed although it's been/being renamed to Major Somnolence Disorder.
I first complained of my symptoms in Jan/Feb 2012. I've had every test going - bloods, urine, neurological exams and sleep studies. It's a diagnosis of exclusion sadly, and not enough people know about it. There is nothing on the website about this, but just because it's a rare neurological disorder that can't be cured doesn't mean it shouldn't be mentioned.

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sowhat said on 06 April 2013

As Lynne Cook already mentioned Vitamin D deficiency is a very common cause of fatigue.

Due to the fact that the majority of people work indoors and use lots of sun screen it is being reported more often in other Northern European countries, the US and Australia.

Yet in the UK it is ignored until adults either break bones doing every day activities such as lifting a book or have a broken bone that won't heal.

If you do manage to get your GP to test your thyroid, iron and B12 levels convince them to also test your Vitamin D level otherwise you will suffer 3-5 years of misery until you break a bone.

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tinker241 said on 16 January 2013

also people who have endomestriosis who get fatigue and get tired when they are in so pain... i have that too and i do get tired a lot and feel useless when i get home from work... i cannot be bothers to do anything but i always get myself up and do things... then by the time i go to bed i crash out.. until early next morning and i do sometimes get very tired through the day... but weekends i just like to sleep at all hours...

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ann3 said on 27 December 2012

I have been suffering from extreme tirdness, all my bloods were ok apart from deficiency in vit d, my symtoms are like lynne's i hope when i start taking vit d tabs to feel much better. It is really getting me down now.

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Pussycat83 said on 13 September 2012

Where is my comment!? I made a comment suggesting narcolepsy! I suffer from it and tiredness is main symptom! I can't it is so under diagnosed & not even mentioned on this site at all! My gp couldn't even figure out what was wrong with me as all blood tests were ok, I requested the test because my dad found an article in a health mag & found out about it! It is a neurological sleep disorder meaning the problem is an in balance in the brain not the blood no blood test will diagnose it! Seriously guys, if you really struggle with staying awake during the day and nodding off all the time, or struggle with maintaining a regular sleep pattern look into it! It is very under diagnosed & often over looked by everyone!

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Pussycat83 said on 13 September 2012

I Would like to add something that has not been mentioned (which I suffer from) - a neurological sleep disorder called narcolepsy which according to wikI is just as common as parkinsons but widely under diagnosed (fewer than 1/4!) before I was diagnosed I had blood tests & tests for just about everything above but all blood tests clear & my gp couldn't find a diagnoses! It was only after my dad read an article in a health mag on narcolepsy & told me to request a test that I was diagnosed! The condition is cause by a lack of a protein in the brain called orexin (which is responsible for controlling appetite & sleep patterns). Scientists used to believe it was hereditary but now believe it could be triggered by an auto-immune response (where your immune system goes into overdrive) following a previous or temporary illness (this makes sense as I had really bad whooping cough when I was a teenager). Anyway in brief main symptoms are e.D.S (excessive daytime sleepiness & sleep attacks at inappropriate times, such as while at work & often disturbed nocturnal sleep & an abnormal daytime sleep pattern, which often is confused with insomnia), cataplexy (loss of muscle tone eg head/jaw dropping, impaired vision, legs feeling like jelly or total collapse on strong emotions such as laughter, anger, fear, surprise etc), sleep paralysis (a phenomenon in which people who are either falling asleep or awakening from sleep temporarily experience a sense of inability to move or talk), hypnagogic hallucinations (vivid, often frightening, dreamlike experiences that occur while dozing, falling asleep &/or while awakening) or automatic behaviour (where you continue to function (talking, putting things away, etc) during sleep episodes, but awakens with no memory of performing such activities). Only 20-25% of people with narcolepsy experience all symptoms so if you are constantly tired & can relate to at least 1 other thing check it out!

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UKNAN said on 31 July 2012

I have been feeling tired for a long time now, I even wake up feeling tired. I have had acid reflux for many years and recently had a hiatus hernia diagnosed and the doctor thought that may have been causing the discomfort in my chest, but as it started getting worse, I had a ct scan and now have been told I have three blocked main arteries, so this accounts for the tiredness, so often we fail to tell the doctor all our symptoms and things could be found so much earlier for us.

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02lady said on 24 May 2012

COPD - Chronic Obstructive Pulmonary Disease.
If you are a smoker or a smoker who gave up, consider whether your fatigue is accompanied by symptoms such as breathlessness. I mistook what I thought was extreme fatigue for thyroid problems, ME, leukemia etc and was tested for each. Because I thought of it as extreme tiredness - for 2 years - and described it as such, the GP never thought to check my lungs. I reached the stage where I slept in my clothes because dressing/ undressing was simply too exhausting. Finally the penny dropped with another GP and I was diagnosed with very severe COPD - I am now on Oxygen.
So if your tiredness is accompanied by shortness of breath, particularly if you wheeze or cough too, or are prone to chest infections, sinusitis etc do consider COPD. If caught early and treated appropriately youwill feel better and lead a normal life. Allowed to go unchecked it will worsen over time - particularly if you continue to smoke - until eventually you can barely function or get pneumonia. I found out too late - hence the oxygen for what is left of my life.

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WHITELIGHT said on 04 June 2011

My tiedness is very deep. I have had blood tests and the doc says they are ok. He says he carnt put a diognosis on to it because all my tests are [positive. Confusing, I feel totaly drained and no symptons of ME, or Fibromyalgia.

I must confess that iv been on Antidepressants for nearl 40 years, until last year i weened myself off them, and its been 10 months now since i last took one, maybe this is the reason of the accute tiedness, i dont know,, a change in the brains chemicals maybe.

Whatever the GP cannot put a diognosis on it, im now trying Reiki treatment so maybe it can boost some energy, and started takin Co Enzime Q 10.

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Lynne Cooke said on 21 March 2011

Deficiency in Vitamin D is also another possible culprit for chronic fatigue. Symptoms can be confused with ME and Fibromyalgia. I'm currently experiencing joint and bone pain, muscle fatigue, general fatigue, sore throat etc. I may have Fibro too but a blood test picked up a very low Vitamin D - so ask your GP for a blood test to to check this out!

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Lynne Cooke said on 21 March 2011

Deficiency in Vitamin D is also another possible culprit for chronic fatigue. Symptoms can be confused with ME and Fibromyalgia. I'm currently experiencing joint and bone pain, muscle fatigue, general fatigue, sore throat etc. I may have Fibro too but a blood test picked up a very low Vitamin D - so ask your GP for a blood test to to check this out!

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EBDOG said on 21 March 2011

Leyla I agree, I have Fibromyalgia and the tiredness is a key symptom, last night I was like a Zombie, I feel asleep putting my daughter to bed and was unable to wake properly after that, the pain wipes me out sometimes.

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