1. Ada
  2. COVID
  3. COVID-19 Symptom: Brain Fog

COVID-19 Symptom: Brain Fog

Written by Ada’s Medical Knowledge Team

Updated on


  • Brain fog can feel similar to the effects of sleep deprivation or stress.
  • Researchers believe that brain fog is related to inflammation of the brain caused by the virus.
  • There’s currently no cure for brain fog, although most cases resolve themselves.
  • In rare instances, brain fog can hinder people from performing their day-to-day activities.

COVID brain fog is one of the most commonly reported symptoms of long COVID. However, it’s also possible to experience it when first infected with COVID. It encompasses a variety of symptoms affecting how we think, focus, and feel and can last anywhere from days to months. Read on to learn about what COVID brain fog feels like, how long it can last, how it’s diagnosed, and what steps you can take to alleviate it. 

What is COVID brain fog?

COVID brain fog is a symptom of infection with SARS-CoV-2, the virus causing COVID-19. It’s commonly cited as one of the symptoms of long COVID. A recent study found that around 7% of those who contract COVID-19 experience brain fog. 1

However, some people may already begin to experience it during the acute phase of the infection. Over time, and as you recover, your brain fog may improve, get worse, or come and go. 2 3

Brain fog may feel different to you than somebody else who reports it. Rather than a single symptom in and of itself, brain fog is an umbrella term for various symptoms related to the way you think. Some of the most commonly reported COVID brain fog symptoms include:  3 4 5

  • Forgetfulness 
  • Inability to concentrate 
  • Inability to find words to express your thoughts 
  • Feeling mentally “fuzzy” or tired 
  • Impaired short-term memory 
  • Confusion 
  • Dizziness

Brain fog is also more commonly reported as a symptom if you have an underlying condition such as depression, anxiety, or stress. 6 3 5

What causes COVID brain fog?

There’s no consensus on what causes brain fog COVID, but there are some solid theories. It has been suggested that brain fog, and other symptoms of long COVID, develop as a result of the inflammation caused by the COVID-19 virus. This inflammation can affect the brain and the body, causing symptoms such as brain fog.

Another study analyzed the brains of COVID patients aged 5 to 80 using a powerful magnetic resonance imaging (MRI) machine. The team found a significant amount of inflammation in each brain, but they also found the presence of fibrinogen, a protein that plays a role in blood clotting. That protein is not typically found in the brain. Its presence suggests that tiny blood clots in the brain could decrease patients’ oxygen levels. In turn, that could lead to brain fog or, in more severe cases, even stroke. 7

It’s not unprecedented for viral infections to cause cognitive symptoms like brain fog. Other diseases, such as Lyme disease and encephalitis, can also cause cognitive delays in patients. 8

How long does COVID brain fog last?

COVID brain fog can last from a few days to a few months. In rare cases, brain fog symptoms can continue for over a year after having COVID-19. It’s also possible not to experience it at all. In most people who report it, brain fog goes away within a few months. 2

Nevertheless, it’s important to remember that the symptoms of COVID brain fog share many similarities with anxiety and depression symptoms. These mental health ailments often arise in individuals with long COVID. It has been suggested that up to half of those who contract COVID-19 develop some degree of anxiety or depression. 

If you’re worried that you might be struggling with your mental health after COVID, talk to your doctor or seek professional help. 

How is COVID brain fog diagnosed?

There’s currently no specific diagnostic test available to help diagnose brain fog after COVID. Rather, the diagnosis is made based on your reported symptoms. For it to be diagnosed as a symptom of long COVID, brain fog should be present for at least 12 weeks following the initial COVID infection. 2 9

How is COVID brain fog treated?

Currently, there’s no definitive post-COVID brain fog treatment available. However, if you’re struggling with your symptoms, there are certain steps you can take that may help you feel better. The UK National Health Service (NHS) has suggested the following to help alleviate brain fog: 4

  • Drinking plenty of water 
  • Exercising and staying active 
  • Maintaining a healthy social life 
  • Getting sufficient sleep 
  • Healthy nutrition 
  • Avoiding excessive alcohol consumption
  • Avoiding smoking

Eating healthily is especially important, as a balanced diet can help reduce inflammation. A study has also shown that Luteolin oil holds some promise as a supplement for COVID brain fog. 3 10

A small trial at Yale Medical School has also been successful at treating COVID brain fog with a 2-drug regime

  • Guanfacine, a drug approved by the Food and Drug Administration (FDA) for the treatment of ADHD, is used off-label to treat traumatic brain injury (TBI) and PTSD
  • N-acetylcysteine (NAC), an antioxidant also used for the treatment of TBI 3

While larger clinical trials are needed to replicate the findings, researchers encouraged patients to ask their doctors about these drugs because they’re FDA-approved and have a safe track record. 11

In certain serious cases of brain fog, cognitive rehabilitation may also be an option. Cognitive rehabilitation encompasses various strategies aimed at regaining optimal brain function. These fall into 2 categories:

  • Reinforcing behaviors that are beneficial to cognitive function
  • Creating new behaviours and thought patterns to overcome cognitive difficulties. 

You should always consult with your doctor if your COVID brain fog symptoms get worse, cause concern or distress, or if it interferes with your day-to-day activities significantly. 

Wrapping up

In summary, brain fog can be a common symptom after COVID and manifests in various ways. It usually begins after the resolution of the acute COVID-19 infection and can last anywhere from days to weeks to months. In most people, brain fog goes away after a while, although in some, it may persist for longer and have a considerable effect on daily life activities. Though there are no definitive treatments available at the moment, hydration, exercise, socializing, sleep, and nutrition all play a role in alleviating the symptoms of brain fog after COVID.


Q: Does COVID brain fog go away?

A: Yes. In most people, COVID brain fog subsides a few days, weeks, or months after the infection. The severity of the infection itself does not correlate with how long your brain fog may last.

Q: Is COVID brain fog permanent?

A: In most people, COVID brain fog resolves itself with time. If you find that many months have passed and your brain fog is not improving, you should consult your doctor to discuss next steps.

Q: What does COVID brain fog feel like?

A: COVID brain fog feels different depending on the person experiencing it. While some may complain of slowed thinking, confusion or forgetfulness, others may struggle with memory or be unable to find the right words to express their thoughts.

Q: Is brain fog a symptom of COVID?

A: Brain fog is common in those who contract the COVID-19 virus and usually becomes apparent after the resolution of the infection’s acute phase.

Q: How to get rid of COVID brain fog?

A: While there’s no definitive treatment for brain fog, healthcare professionals recommend improvements in diet and lifestyle to help reduce inflammation and promote the body’s natural healing process.

Q: How long does brain fog last after COVID?

A: For most patients, brain fog caused by COVID gets better in the months after the infection. In rare cases, COVID brain fog can persist for over a year.

Q: Does COVID cause brain fog?

A: COVID is known to cause inflammation in the body. That inflammation can be a cause of brain fog in many patients.

Q: Can the COVID vaccine cause brain fog?

A: Studies have noted short-term memory loss as a rare side effect of the vaccine. However, the researchers concluded that the vaccine’s benefits outweighed the risk. 12