Common causes of brain fog and what you can do about it

Brain fog can often be cleared away with the right treatment. But before that can happen, you need to find out what's causing the “fog”—so read on to learn about common causes, related health conditions, and more.

“Brain fog” can make you feel like you're sleepwalking through life. People with this symptom often report feeling tired, difficulty focusing, forgetfulness, or hazy thought processes. With brain fog, even simple tasks can become a challenge. 

Brain fog can have many possible causes, including health conditions like hypothyroidism or depression. Factors related to lifestyle—like long-term stress or your diet—can also cloud your thinking. 

Finding the cause of brain fog isn’t always easy, but in many cases, lab testing can help uncover the cause of brain fog. With Everlywell’s at-home lab tests, you can easily check B vitamin levels, thyroid hormones, potential food sensitivities—and more.

Here are 3 tests that can help you find the cause of symptoms like brain fog.
Slide 1 of 3
  • B Vitamins Test
    $89
    This at-home test is an easy way to evaluate your levels of three different B vitamins in your body. It can...
    Measures
    Vitamin B6 (pyridoxine), Folate (Vitamin B9/folic acid), and more
    Learn more
    Add To Cart
  • Thyroid Test
    $159
    Easily measure your levels for the 3 main thyroid hormones (TSH, T3, and T4) plus thyroid antibodies with this...
    Measures
    Thyroid-Stimulating Hormone, TPO Antibodies, Free T3, Free T4
    Learn more
    Add To Cart
  • Food Sensitivity Test
    $159
    This at-home test measures your body’s immune response to 96 foods to help provide guidance on what foods may...
    Measures
    IgG Reactivity to 96 Foods
    Learn more
    Add To Cart

Common causes of brain fog

Common causes of brain fog include:

  • Vitamin deficiencies - A healthy diet isn't just vital for physical health: your diet also plays a significant role in mental performance. A nutritionally inadequate diet can trigger vitamin deficiencies which may lead to brain fog. B vitamins like B9 and B12, for example, help keep your brain healthy. So if your levels of these essential nutrients are too low, you might experience cognitive problems [1]. See if you’re getting enough B vitamins with this easy-to-use, at-home test.

  • Food sensitivities - Sensitivities to certain foods can cause various symptoms—including brain fog—hours or days after you eat those foods. People have reported that the fog lifts after eliminating those foods from their diet. (The Everlywell at-home Food Sensitivity Test makes it easier to find the symptom-causing foods in your diet.)

  • Thyroid disorders - If your thyroid gland isn’t making enough hormones, a condition called hypothyroidism—or underactive thyroid—can develop. Brain fog is one of the possible symptoms of this thyroid disorder [2], which is up to 10 times more common in women than in men [3]. Test your thyroid hormones from the comfort of home.

  • Blood pressure changes - Abnormal blood pressure is sometimes responsible for brain fog. That’s because your blood supplies oxygen to your brain—so inadequate blood flow can affect your mental function.

  • Mental health conditions - If you notice a lack of mental clarity, mental health conditions like anxiety or depression could be the culprit [4, 5]. Untreated attention-deficit/hyperactivity disorder (ADHD) could also be to blame [6]. 

  • Medication side effects - Some prescription medications come with side effects that can make your thinking feel cloudy. These side effects often appear in the first few weeks of taking a new drug. But sometimes, side effects appear later on. You may also develop brain fog after changing a medication dosage or combining medications. If this is something you might be experiencing, talk with your healthcare provider—and let them know which medications you're taking. Your provider can help you determine whether these drugs are causing side effects.

  • Heavy metal exposure - In some cases, brain fog can be a sign of exposure to toxic heavy metals like mercury or arsenic—which can trigger confusion, fatigue, or memory loss [7].

Check for heavy metal exposure: The Everlywell Heavy Metals test lets you check for exposure to toxic heavy metals like arsenic, mercury, and cadmium from the convenience of home.

Get the Everlywell Heavy Metals Test

Health conditions related to brain fog

Brain fog can be connected to several different health conditions, including:

  • Depression - Depression can affect your attention span and make it hard to focus [8]. If you think you're suffering from depression, it's essential to get help right away (treatment can often lift depression). 

  • Stress - Stress exhausts your brain, triggers inflammation, and disrupts your sleep patterns. People with high levels of stress often have mental fatigue. This fatigue can affect your focus and concentration. The Everlywell at-home Sleep and Stress Test can reveal if you may be chronically stressed—resulting in brain fog.

  • Anemia - If you don't have enough healthy red blood cells—a condition known as anemia—you may feel fatigued or depressed [9]. Anemia is often triggered by deficiencies in vitamin B9 or B12. 

  • Fibromyalgia - Fibromyalgia is linked to chronic pain, sleep problems, and mood and memory issues [10]. Researchers aren't sure what causes fibromyalgia. But symptoms often appear after a physical trauma, illness, infection, or stressful event. While there is no cure for fibromyalgia, treatment may help you feel better.

  • Chronic fatigue syndrome (CFS) - CFS is a complex disorder that causes severe, ongoing fatigue. It may be linked to infections, immune system problems, or hormonal imbalances. Exhaustion caused by CFS can also impair memory and concentration [11]. There is no specialized test for CFS, but blood work may help you get an accurate diagnosis.

  • Dementia - Most cases of brain fog are not linked to dementia. But if you're over 65, report any confusion or disorientation to your healthcare provider right away. If your provider suspects dementia, they can perform specialized tests to make a diagnosis. There is no blood test for dementia. But cognitive testing can determine whether you're showing signs of dementia.

  • Sleep disorders - Even if you log eight hours of sleep each night, poor sleep quality can still leave you exhausted and unable to focus. A disorder like sleep apnea is often to blame for poor sleep quality.

Regular thyroid screening is key: A healthy thyroid is important for many of your body’s functions (and thyroid disorders can cause brain fog). The American Thyroid Association recommends thyroid screening in adults beginning at age 35 and every 5 years after [12].

Get the Everlywell Thyroid Test

Seeking medical care for brain fog

If you’re wondering how to get rid of brain fog after it’s begun affecting your quality of life, it's a good idea to see your healthcare provider. Seek medical care right away if you have symptoms like sudden amnesia or slurred speech. These can be signs of a medical emergency.

During an initial evaluation, your healthcare provider may ask for more details about your brain fog. If possible, prepare notes in advance so you can let your provider know what specific symptoms you've noticed. You may want to mention recent changes in your sleep schedule, dietary changes, or other lifestyle changes.

There’s no single brain fog cure. Instead, your provider will consider your symptoms, medical history, and lab test results. From there, they may make a diagnosis and help develop a treatment plan—which may involve medication, psychotherapy or counseling, or lifestyle changes.

If your healthcare provider isn't sure what’s causing your brain fog, they may refer you to a specialist who can perform more in-depth evaluations.

Key risk factor for B vitamin deficiency: The risk of vitamin B12 deficiency, which can contribute to brain fog, increases with age.

Check your B vitamin levels

Ways to reduce brain fog

A healthy lifestyle can help protect your cognitive function. You can help support your memory and focus by:

  • Eating a well-balanced, nutritionally-adequate diet

  • Getting regular exercise

  • Getting enough sleep each night

  • Meditating

  • Participating in stress-releasing hobbies

How stressed are you? Long-term stress can negatively affect memory, learning, and other cognitive functions.

Take the Everlywell Sleep and Stress Test to see if you might be experiencing chronic stress.

Common questions about brain fog

What is brain fog?

“Brain fog” is cognitively experienced as slower thinking, lack of concentration, forgetfulness, and/or confusion. These symptoms affect your thinking processes, understanding, judgment, and memory.


What does brain fog feel like?

Many people with brain fog describe their thinking as “cloudy.” They might have trouble focusing while reading a book or email. Others report problems with their memory. For example, they may misplace their phone, keys, or briefcase. Brain fog can also interfere with your ability to absorb and retain new information.


How long does brain fog last?

Brain fog symptoms can vary from person to person. Sometimes, brain fog can be temporary. But some people report that their “fog” worsens over time. Others find that their symptoms come and go. In many cases, addressing the underlying cause helps clear the “fog.”


Is there a brain fog treatment?

Treating brain fog comes down to addressing the root cause. Because there are many possible causes for brain fog, there isn’t a single treatment approach that will work for everyone.


How can I get rid of brain fog?

The first step is to find out what's causing the brain fog. Brain fog is often a sign of temporary stress or fatigue. But it can also indicate a more serious medical problem. 

Lab tests can help screen for many common causes of brain fog—so consider trying an Everlywell at-home lab test that measures markers associated with brain fog.

Here are 3 tests that can help you find the cause of symptoms like brain fog.
Slide 1 of 3
  • B Vitamins Test
    $89
    This at-home test is an easy way to evaluate your levels of three different B vitamins in your body. It can...
    Measures
    Vitamin B6 (pyridoxine), Folate (Vitamin B9/folic acid), and more
    Learn more
    Add To Cart
  • Thyroid Test
    $159
    Easily measure your levels for the 3 main thyroid hormones (TSH, T3, and T4) plus thyroid antibodies with this...
    Measures
    Thyroid-Stimulating Hormone, TPO Antibodies, Free T3, Free T4
    Learn more
    Add To Cart
  • Food Sensitivity Test
    $159
    This at-home test measures your body’s immune response to 96 foods to help provide guidance on what foods may...
    Measures
    IgG Reactivity to 96 Foods
    Learn more
    Add To Cart
Everlywell at-home lab tests may help you discover more about the brain fog affecting you.

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