Brain Fog: 20 Causes and Symptoms

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For some, brain fog is what happens when you drink too much cough medicine or stay up late at night.  For others, people with vitamin B12 deficiency, pernicious anemia, or fibromyalgia, brain fog is part of everyday life.  In fact, many people who experience brain fog have had it all their lives, and don’t remember a time when they didn’t have trouble remembering numbers, responding with clever banter, or finding their way out of a parking lot…


This is Part I of Brain Fog, which focuses on causes and symptoms.  Part II is Brain Fog: 20 ways to deal

What is brain fog?

Brain fog is a lot easier to describe than it is to define, since scientists are not sure exactly what causes it, and most doctors don’t recognize it as a medical condition, but rather a symptom of other illnesses.

Here are some terms people use to describe their brain fog:

  • Mental fuzziness or confusion that is caused by a primary illness, condition, or other stimuli like food, drugs, or lifestyle habit
  • Cognitive dysfunction
  • Fibro haze
  • Brain drain
  • Brain farts
  • Space case
  • Stupid- This is wrong! Having brain fog does not mean that you are less intelligent than others are.  It only means that you have a real disorder with real symptoms, and brain fog is one of them.

What are the symptoms of brain fog?

Most people who suffer brain fog say that they feel tired all the time, even after getting a good night’s rest. But there are lots of other seemingly unrelated symptoms that indicate brain fog besides feeling like you always have a dark cloud over your head.

Here are some of the most common symptoms of brain fog:

  1. Fatigue
  2. Short-term memory loss- forgetting recent reminders, shopping lists, things you talked about a few days ago
  3. Difficulty with math- adding in your head, sequencing, remembering numbers
  4. Forgetting what you were going to say in conversation
  5. Difficulty concentrating or focusing while reading
  6. Difficulty recalling words that should be on the tip of your tongue
  7. Low attention span
  8. Easily confused
  9. Getting lost easily, even in familiar places
  10. Difficulty thinking clearly
  11. Difficulty with multitasking
  12. Difficulty solving problems
  13. Depression
  14. Anxiety
  15. Low spatial awareness- stepping on others’ feet, for example
  16. Absentmindedness
  17. Low learning curve
  18. Difficulty learning new skills
  19. Low energy
  20. Loss of creativity

What causes brain fog?

Since brain fog is not really a medical or psychiatric term, we likewise don’t have a specific answer as to what causes it.  Brain fog is linked with lack of sleep, dementia, chronic pain, brain disorders, vitamin deficiencies, and unusual blood flow to the brain.

Here are 20 conditions and illnesses that correlate with brain fog:

  1. Fibromyalgia (FMS)
  2. Chronic fatigue syndrome (CFS)
  3. Vitamin B12 deficiency
  4. Pernicious anemia
  5. Lupus
  6. Migraines
  7. Meniere’s disease
  8. Menopause
  9. Anxiety
  10. Depression
  11. Diabetes
  12. Multiple sclerosis
  13. Graves’ disease-hyperthyroidism
  14. Chronic thyroiditis (Hashimoto’s disease)- hypothyroidism
  15. Adrenal fatigue
  16. Sjogren’s Syndrome
  17. Insomnia
  18. Medical reaction
  19. Allergy
  20. Lyme disease

Please tell us…

Do you have anything to add to this article?  We would love to know!

Read more about vitamin B12 and your brain:

Brain Fog: 20 ways to deal

Here’s Your Brain on B12 Deficiency- Memory Loss and Aging

How to keep Vitamin B12 Deficiency from Shrinking your Brain

Tired of being Tired all the Time…It’s Tiring!

7 Reasons You Have Brain Fog…And What to do About It


Brain Fog/Fibro Fog in Fibromyalgia & Chronic Fatigue Syndrome

Migraine and Brain Fog Tips and Tricks

What is Brain Fog?