Brain fog is a type of cognitive dysfunction characterized by confusion, memory issues, and lack of focus. It’s not its own diagnosis but a symptom of an underlying medical condition.

Brain fog itself is not a medical condition but instead a symptom of other medical conditions. It’s a type of cognitive dysfunction involving:

  • memory problems
  • a lack of mental clarity
  • poor concentration
  • an inability to focus

Some people also describe it as mental fatigue. Depending on the severity of brain fog, it can interfere with your work, school, or other daily tasks. But it does not have to be a permanent fixture in your life.

We’ve partnered with C60 Power to discuss six possible causes of brain fog.

There are several reasons why brain fog may happen. Once you figure out the underlying cause, you can begin managing it.

Here are six possible causes:

1. Stress

Chronic stress can increase blood pressure, weaken the immune system, and trigger depression, according to a 2017 review of research. It can also cause mental fatigue.

When your brain is exhausted, it becomes harder to think, reason, and focus.

2. Lack of sleep

Poor sleep quality can interfere with how well your brain functions, according to 2021 research. The goal is to usually aim for 8–9 hours of sleep every night.

Sleeping too little can lead to poor concentration and cloudy thoughts.

3. Hormonal changes

Research from 2018 suggests hormonal changes can also cause brain fog.

Levels of the hormones progesterone and estrogen increase during pregnancy. This change can affect memory and cause short-term cognitive impairment.

Similarly, a drop in estrogen levels during menopause can cause forgetfulness, poor concentration, and cloudy thinking, according to 2019 research.

4. Diet

Diet can also play a role in brain fog.

Vitamin B12 supports healthy brain functioning. A 2021 research review found that a vitamin B12 deficiency can affect cognitive function and bring about brain fog.

If you have food allergies or sensitivities, brain fog may develop after eating certain foods. These include:

Removing trigger foods from your diet may improve symptoms.

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5. Medications

If you notice brain fog while taking medication, talk with your doctor. Brain fog is a known side effect of certain medications, such as certain sleep and pain medications. Lowering your dosage or switching to another drug may improve your symptoms.

Brain fog can also occur after cancer treatments. This is referred to as chemo brain.

6. Medical conditions

Medical conditions associated with inflammation, fatigue, or changes in blood glucose levels can also cause mental fatigue.

For example, brain fog is a symptom of chronic fatigue syndrome (CFS), which involves persistent fatigue for a prolonged period of time, according to 2020 research.

According to a 2015 research review, people who have fibromyalgia may experience similar fogginess on a daily basis.

Other conditions that may cause brain fog include:

Talk with a doctor if you have a persistent lack of clarity that worsens or does not improve.

A single test cannot be used to diagnose brain fog. Brain fog may signal an underlying issue, so healthcare professionals will conduct a physical examination and ask about your:

  • mental health
  • diet
  • level of physical activity
  • current medications or supplements

You should let a doctor know about other symptoms you might have. For example, someone with hypothyroidism may have brain fog along with hair loss, dry skin, weight gain, or brittle nails.

Blood work can help your doctor identify the cause of your brain fog. A blood test can detect the following:

  • irregular glucose levels
  • poor liver, kidney, and thyroid functions
  • nutritional deficiencies
  • infections
  • inflammatory diseases

Based on the results, your doctor will determine whether to run further tests. Other diagnostic tools may include imaging tests to look inside the body, like X-rays, magnetic resonance imaging (MRI), or computerized tomography (CT) scans.

Your doctor may also conduct allergy testing to check for allergies or a sleep study to rule out a sleep disorder.

Keeping a food journal can help you determine if your diet contributes to brain fog.

If you need help finding a primary care doctor, then check out our FindCare tool.

Brain fog treatment depends on the cause. For example, if you have anemia, iron supplements may increase your production of red blood cells and reduce your brain fog.

If you’re diagnosed with an autoimmune disease, a doctor may recommend a corticosteroid or other medication to reduce inflammation or suppress the immune system.

Sometimes, relieving brain fog is a matter of correcting a nutritional deficiency, switching medications, or improving the quality of your sleep.

You can try these strategies at home to relieve brain fog:

  • Get at least 8–9 hours of sleep every night.
  • Manage your stress levels, knowing your limitations. Find activities you enjoy doing and try to make time for them.
  • Avoid excessive alcohol and caffeine.
  • Exercise regularly, but not too close to bedtime.
  • Strengthen your thinking abilities — you can try volunteering or solving brain puzzles.
  • Increase your intake of protein, fruits, vegetables, and healthy fats.

Brain fog can be frustrating, but relief is possible. You should not ignore your symptoms because, if left untreated, brain fog can impact the quality of your life.

Once the underlying cause is addressed, your mental clarity can improve.