What causes brain fog? Diagnosis, prevention, and treatment

Medically reviewed by Anne Jacobson, MD, MPH
Board-Certified Family Physician
Updated Nov 18, 2025  •  Published Jun 21, 2023
Fact Checked
Brain fog causes
In this article:

Overview:

Brain fog is not a medical condition. It’s a term that describes a cluster of symptoms, including mental fatigue, mental slowness, poor concentration, easy distractibility, “fuzziness,” difficulty communicating, memory problems, or a sense of feeling disconnected. In the most general sense, brain fog seems most similar to cognitive problems people have when they are sleep-deprived or overworked. Many symptoms people describe as brain fog are also characteristic of ADHD.

So what is brain fog? Healthcare professionals don’t use it as a diagnosis. They may use the term ”mild cognitive impairment” to describe a decline in cognitive function. But what doctors mean by “cognitive impairment” is usually a more significant impairment than for people who experience “brain fog.” 

While there are many possible causes of short-term and long-term cognitive dysfunction, healthcare professionals believe inflammation is the primary culprit behind brain fog. Sleep disruption, fatigue, mental health disorders, poor nutrition, central nervous system disorders, and blood flow problems are also important contributing factors. 

RELATED: 10 signs of inflammation to watch out for

Key takeaways:

  • Brain fog is a common health condition that can affect anyone regardless of age, sex, race, or ethnicity. 

  • Brain fog is affected by lack of sleep, chronic stress, anxiety, depression, dementia, inflammatory conditions, infections, injuries, hormone changes or disorders, poor nutrition, and drugs.

  • Risk factors for brain fog include stress, overwork, sleep problems, mental health conditions, autoimmune conditions, hormone changes, poor diet, and certain medications.

  • Symptoms of brain fog include mental fatigue, difficulty concentrating, forgetfulness, dissociation, difficulty communicating, fuzzy thinking, and inattentiveness.

  • Brain fog is typically self-diagnosable.

  • Brain fog typically resolves without medical treatment within variable timelines but may be a chronic complaint in people with conditions such as autoimmune disorders, fibromyalgia, or long-term COVID-19 complications.

  • Treatment of brain fog may include adopting different sleep and dietary habits, reducing work or computer time, reducing stress, exercising, or treatment of underlying medical conditions.

  • Brain fog may be prevented or improved with good sleep hygiene, stress reduction, work reduction, exercise, and a healthy diet.

What causes brain fog?

Common factors that may contribute to or worsen brain fog include:

  • Lack of sleep

  • Overwork

  • Too much computer screen time

  • Stress

  • Poor diet

  • Alcohol use or withdrawal

  • Illicit drug use or withdrawal

  • Anxiety

  • Depression

  • Lack of exercise

Medical conditions that are commonly associated with brain fog include:

  • Autoimmune diseases, immune system reactions, and other inflammatory conditions

  • Central nervous system inflammation due to COVID, viral infections, brain infections, Lyme disease, multiple sclerosis, cancer treatments, chronic fatigue syndrome (CFS), or other causes.

  • Chronic central nervous system conditions such as fibromyalgia, Parkinson’s disease, multiple sclerosis, or dementia

  • Sleep disorders such as obstructive sleep apnea

  • Hormonal changes during menopause, postpartum, or with conditions such as thyroid disorders

  • Brain injury

  • Blood flow problems such as persistent orthostatic hypotension (low blood pressure when standing up) or stroke

  • Side effects of certain prescription medications

Risk factors for mild cognitive impairment

When symptoms of brain fog happen in an older adult, healthcare professionals may use the term “mild cognitive impairment.” Sometimes these symptoms are reversible with medication changes or treatment of underlying medical conditions. The changes may occur slowly over time and are related to the brain's normal aging. Or they may be an early sign of a more progressive condition like Alzheimer’s.

Significant risk factors for mild cognitive impairment include:

  • Growing older

  • Depression

  • Stress responses

  • Anxiety

  • Diabetes

  • High blood pressure

  • High cholesterol

  • Obesity

  • Lack of exercise

  • Smoking

Is brain fog serious? When to see a doctor

Improvements in sleep, diet, exercise, and stress management may significantly improve the symptoms of brain fog. 

However, see a doctor if other symptoms of a psychiatric or medical condition are present. Treating an underlying condition may help to clear the symptoms of brain fog. 

If impaired brain function impacts one’s daily life, doesn’t go away, or worsens, it’s vital to see a healthcare provider. In particular, when older people experience brain fog on a day-to-day basis, they may be at risk for a serious illness such as Alzheimer’s disease. It’s essential to see a doctor earlier rather than later.

How is brain fog diagnosed?

Brain fog is not a diagnosis but rather a term that is used to describe a variety of symptoms. A healthcare professional has a bit of detective work to do to find out why it’s happening. The first step is to take a complete medical history and perform a physical and neurological examination. The goal is to find out what the actual problems are with memory loss, thinking, attention, and judgment. The second concern is to determine how much these cognitive problems affect daily function. Be aware that questions about mood, sleep, work, stress, and medications will be part of the interview. 

Blood tests can help identify underlying medical problems such as vitamin deficiencies, infections, inflammatory conditions, or hormone disruptions. A mental health evaluation can help identify problems such as anxiety or depression.

Is brain fog hereditary?

Brain fog itself is not hereditary. It’s probably caused by a combination of medical conditions and lifestyle factors. 

If brain fog meets the diagnostic criteria for cognitive impairment, there are some  medical conditions that have a genetic component, such as Alzheimer’s disease. 

Is brain fog curable?

Brain fog is usually reversible. No matter the underlying cause, practicing healthy habits will often improve the symptoms. These include:

  • Getting enough sleep

  • Eating a healthy diet

  • Avoiding overwork or multitasking

  • Reducing screen time

  • Managing stress

  • Practicing relaxation techniques

  • Exercising

  • Engaging in mentally stimulating activities

  • Avoiding alcohol and drugs

If brain fog is due to a medical condition such as hypothyroidism, the brain fog clears up when the condition is treated. However, some conditions that may cause brain fog, such as sleep apnea or mental health issues, may be more complex and time-consuming to treat. 

Brain fog due to prescription medications usually clears up when a medication is stopped or the dose is lowered. However, brain fog caused by chemotherapy—commonly called “chemo brain” or “chemo fog”— doesn’t always clear up when cancer treatments stop. It may take a while, sometimes months or years, to resolve. 

Infections may cause lingering fatigue and cognitive issues. This is due to persistent inflammation in the brain. There are currently no medical treatments for fatigue or brain fog that persist after a viral infection, but healthy lifestyle habits can help to improve symptoms.

If brain fog is diagnosed as mild cognitive impairment, it may or may not be treatable. If it’s associated with chronic central nervous system problems such as multiple sclerosis or dementia, the cognitive impairment will usually worsen over time. While it can’t be cured, its progress can be slowed with certain types of medications and lifestyle changes.

How to prevent brain fog

Here are a few tips to prevent or improve brain fog:

  • Get seven to eight hours of sleep every night 

  • Avoid overworking when possible

  • Restrict the amount of time spent in front of screens or on a smartphone

  • Take regular breaks from working or screen time

  • Eat a healthy diet

  • Learn stress management techniques

  • Practice relaxation techniques such as deep breathing, yoga, or meditation

  • Exercise regularly

  • Avoid substances like alcohol or other drugs that can affect brain function

Even if brain fog is caused by a treatable medical condition or a progressively worsening disease, these techniques contribute to good brain health and may help with cognitive function.

RELATED: The best diet for mental health

Most importantly, see a doctor if brain fog does not get better

Brain fog is usually self-diagnosable and treatable with lifestyle changes, but not always. Brain fog may also be a sign of an underlying medical condition. See a doctor if symptoms don’t go away, get worse, or impact your ability to function.

FAQs about brain fog causes

What deficiency causes brain fog?

A poor diet can contribute to brain fog by causing inflammation or leaving out important nutrients. Vitamin deficiencies such as vitamin B12 deficiency may contribute to cognitive issues. When diagnosing cognitive impairment, a healthcare provider will often test B12 levels but may also test for vitamin D or folate deficiencies.

Why won't my brain fog go away?

The simplest reason that brain fog won’t go away is that the problem causing it isn’t being fixed. It could be unresolved lifestyle habits, treatable medical conditions, or chronic and progressive conditions. No matter what the cause, see a doctor if brain fog just won’t go away. 

Is brain fog a symptom of a brain tumor?

Confusion and fuzziness can be symptoms of a primary or secondary brain tumor, but cognitive symptoms are not the most common brain tumor symptoms. Even if brain fog is experienced, a brain tumor will usually involve other symptoms such as headaches, seizures, weakness, balance problems, language problems, and vision changes. If these problems are experienced collectively, it’s time to get medical attention.

What’s next? Additional resources for people with brain fog

Test and diagnostics

Treatments

Scientific studies and clinical trials

Medically reviewed by Anne Jacobson, MD, MPH
Board-Certified Family Physician

Anne Jacobson, MD, MPH, is a board-certified family physician, writer, editor, teacher, and consultant. She is a graduate of University of Wisconsin School of Medicine and Public Health, and trained at West Suburban Family Medicine in Oak Park, Illinois. She later completed a fellowship in community medicine at PCC Community Wellness and a master's in Public Health at the University of Illinois-Chicago. She lives with her family near Chicago.

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