What Is Brain Fog? 9 Causes and Solutions

Updated: Oct. 10, 2022

If your brain feels chronically fuzzy and you just can't do mental tasks like you used to, you may be dealing with brain fog. Here's how to get rid of it.

Anyone can experience brain fog

“It’s funny you’re calling me for this interview late on a Monday night, after a long day at work, because I’m feeling some brain fog and mental exhaustion myself at the moment,” says Scott Kaiser, MD, the director of cognitive health at the Brain Health Center at the Pacific Neuroscience Institute in Santa Monica, California.

As a doctor, he helps his patients deal with brain fog all day long—it’s one of the most common cognitive symptoms his patients report—but he proves that the mental fuzziness can strike anyone, even the experts.

In fact, this “clouding of consciousness” is a state that everyone has likely experienced at some point, says Sanam Hafeez, a neuropsychologist and faculty member of Columbia University in New York City.

When brain fog is not normal

Some people experience this condition on a persistent basis, and it may affect their ability to live their daily lives or cause serious disability.

This type of persistent, damaging brain fog is a hallmark of Covid-19 long haulers, people who deal with effects from the virus for weeks or months after they recover from the acute infection.

But while it’s frustrating that more people are being affected by it, it has brought the brain fog conversation into the mainstream. It’s gaining broader acceptance and understanding, says Dr. Kaiser.

“It’s important to recognize when it’s become a problem so you can get help,” he says. “Brain fog isn’t something you just ‘have to live with’ or write off as ‘I’m just getting old.'”

(Getting older can affect your cognition, so make sure you’re doing these 15 things to protect your brain as you age.)

Brain fog isn’t a clinical term

“Brain fog” is a very common description people use to describe that feeling of mental exhaustion or fuzziness where it’s hard to think clearly.

However, it’s not a clinical term, so you won’t see it on a medical chart and you can’t be diagnosed with it. This may lead some health practitioners to dismiss it as unimportant.

But just because it’s hard to define and can differ from person to person doesn’t mean it’s not valid. “Brain fog is a very real and misunderstood condition,” says Dr. Kaiser.

And it may point to other underlying health issues.

“The reason it is challenging is that it is not so much a sign or diagnosis as it is a symptom. Or even more confusing, an interpretation of a symptom,” says Brandon Pope, MD, neuroscience chief and stroke medical director at UCHealth Highlands Ranch Hospital and an associate professor at the University of Colorado School of Medicine in Denver.

What does brain fog feel like?

How exactly brain fog feels is unique to each person, but it always represents a marked decline in cognitive functioning, says Hafeez.

Overall, you may feel like you’re just not able to think or do mental tasks as well as you used to.

Common brain fog symptoms as:

  • Poor concentration

  • Forgetfulness

  • Confusion

  • Moodiness

  • Inability to pay attention or focus

  • Feeling “checked out”

  • Mental exhaustion

  • Lack of mental clarity

  • Inability to multitask

There generally aren’t any physical symptoms of brain fog, although some people report a headache or exhaustion, says Dr. Pope.

Questions your doctor may ask

Brain fog can be caused by lifestyle and environmental factors or by an underlying medical condition.

To help figure out the source of your mental fuzziness, your doctor will need to get an accurate medical history, says Dr. Kaiser. Be prepared to answer these questions from your doctor:

  • When did it start?

  • What does it feel like to you?

  • Is it chronic, or does it come and go? Is there a pattern?

  • Have you been able to identify anything that triggers it?

  • Have you had any illnesses or changes in your health recently?

  • Have you experienced any major events recently, like a death of a loved one or a job change?

If your brain fog is severe, you may want to write down your answers to these questions and bring them with you to your appointment.

It’s also helpful to bring a clear-minded friend or family member to help you process what the doctor says.

Mixed-race Young Adult Woman Works at Home Using Laptop ComputerJustin Lewis/Getty Images

Common lifestyle causes and solutions for brain fog

“If someone is experiencing decreased levels of cognitive function, or brain fog, it could be due to a myriad of underlying conditions from the very benign to the potentially more serious,” says Dr. Pope.

The list of things that have brain fog as a symptom is so long it couldn’t be written in one article, and only your doctor can help you pinpoint yours.

However, there are some common causes you should consider, starting with your lifestyle.

Poor sleep

Not getting enough quality sleep is the top cause for brain fog, says Hafeez.

During non-rapid eye movement (NREM) sleep, the brain filters important memories. Rapid eye movement (REM)—the deepest stage of sleep—allows the memories to become concrete and plays a role in memory consolidation.

When someone does not get enough sleep, memory consolidation is affected. That’s why brain fog is a common symptom of narcolepsy.

Your doctor may ask you to improve your sleep hygiene and, if that doesn’t help, may refer you to a sleep study.

Poor diet

Nutritional deficiencies can cause chronic mental fogginess.

The most common culprits are low iron, magnesium, vitamin D, or vitamin B12 levels.

The latter is of particular concern for vegans who may not get it in their diet and need to supplement B12. Your doctor can check all of these with a blood test.


Eating foods containing gluten, a protein found in wheat, barley, and rye, has been linked to brain fog in people who have non-celiac gluten sensitivity, according to a 2020 study published in PLOS One.

“There is little research as to why gluten affects the brain, but it is known that gluten can affect the neurological system and cause headaches and brain fog,” says Hafeez. “This may happen because gluten alters gut function, and changes in the gut microbiome affect cognitive centers in the brain and ultimately affect brain function.”


Anxiety, worry, long work hours, parenting, and other types of chronic mental pressure can have a big effect on brain function.

All your mental energy becomes devoted to the stressors, and you feel foggy when you try to focus on something else.

It’s easy to let self-care slide when you’re stressed, but for your brain’s sake, it’s important to make sure you’re doing stress-relieving techniques.

Medical causes and solutions for brain fog

Brain fog is an extremely common symptom of many types of medical issues. Sometimes it’s a result of the underlying condition; other times, it stems from treatment, says Dr. Kaiser.


Many common medications, particularly sleeping pills and meds used to treat mental illnesses, can cause your brain to feel fuzzy or unclear.

If you’ve recently started a new medication or changed the dose, that may be the cause of your problem.

Always tell your doctor about all of the medications you take—that goes for both prescription and over-the-counter drugs.

Hormonal changes

An inability to concentrate and mental fuzziness are signs of both menopause and andropause, says Hafeez.

Hormonal changes in your body directly affect your brain and its ability to function, particularly in women.

“Estrogen levels contribute to memory and other brain processes, and when estrogen levels lessen, occasional lapses in the brain can occur,” she says.

This also explains “pregnancy brain,” the type of brain fog that gestating women often experience.

Mental illness

It’s no surprise that illnesses that affect the mind, including anxiety, depression, and attention-deficit hyperactivity disorder (ADHD), can cause mental cloudiness.

It’s especially important to get evaluated by a mental health professional if you have a family history of mental illness or have had a big change in your life recently.


Diabetes, stroke, hypothyroid, the flu, fibromyalgia, autoimmune disorders, and some types of cancers are just a handful of diseases that have brain fog as a symptom. Chronic illness, including chronic pain, has also been linked to brain fog symptoms.

One illness that comes up a lot in relation to brain fog is dementia, says Dr. Kaiser.

“People may be afraid to bring up their forgetfulness as they worry it’s the beginning of dementia, but ignoring it won’t make it go away, and the sooner we diagnose you, the sooner we can start treating it,” he says.

If lifestyle changes haven’t helped and/or you have symptoms in addition to the brain fog, your doctor may want to run additional tests to rule these conditions out.

Here are more medical reasons for your brain fog.

Brain fog and Covid-19 long hauler syndrome

Covid-19 has brought brain fog front and center—it’s one of the most common symptoms that lasts after the acute infection has resolved.

More research needs to be done into Covid-19’s effect on the brain, but the condition is likely due to inflammation in the blood vessels that feed the brain, says Dr. Kaiser.

“We call it Covid fog,” says Rajeev Fernando, MD, an infectious disease physician and director of the division of infectious diseases at Stony Brook Southampton Hospital in New York. “It’s a newer syndrome we’ve identified, where patients end up experiencing mental clouding for months.”

If you’re experiencing “Covid brain fog,” there’s a good chance mental fuzziness is not the only symptom you’re still feeling.

“The virus can attack more than one system at a time, including the brain, which may explain the strange constellation of symptoms doctors have been seeing in Covid-19 patients, including nausea, diarrhea, loss of smell or taste, heart damage, and kidney failure but also neurological problems, including stroke and brain fog,” says Dr. Fernando.

Here’s everything you need to know about brain fog from Covid-19, including how to deal with it.

How to deal with brain fog

There’s no single treatment for brain fog.

“The treatment will always depend on the cause itself,” says Dr. Pope. “I think it takes a combination of a solid history and physical examination by a doctor to begin to get to the why and discuss potential treatments.”

In the meantime, he suggests you start by going back to the fundamentals of good self-care, including getting enough sleep, eating a healthy diet, exercising regularly, and lowering your stress.

Other things that may help include taking a vacation or working on puzzles or brainteasers.

Make sure all of your physical and mental health conditions are being treated appropriately and are under control.

(Here’s what doctors think about brain-boosting supplements.)

When to call your doctor

In and of itself, brain fog typically isn’t an emergency, says Hafeez.

However, if it appears suddenly, is a new symptom, or is seriously impacting your life, make an appointment to see your physician.

Rarely, it can be serious. If you have a brain fog accompanied by a severe headache, difficulty speaking, loss of vision, weakness, tingling, or numbness you may be having a stroke and should seek medical care immediately.