How Common is COVID-19 Brain Fog and How Long Does It Last?

From early 2020, the novel coronavirus started spreading across the world with an unprecedented speed of transmission. From being first detected in Wuhan, China, in 2019, this new virus reached countries as far away as the Philippines and the United States. Officially named SARS-CoV-2, the novel coronavirus has been responsible for causing over 100 million infections around the world and causing over 2.5 million deaths.1

The disease that is caused by getting infected by the SARS-CoV-2 is known as COVID-19, which is the commonly used name to refer to this coronavirus disease.

The common symptoms of COVID-19 include shortness of breath, cough, fever, and fatigue.2

Some of the less common symptoms of COVID-19 include:

At the same time, almost 25 percent of people who have developed COVID-19 have also experienced neurological symptoms, symptoms that affect your nervous system and brain.3

One of the common neurological symptom that people with COVID-19 have reported is lingering brain fog. In some cases, this type of brain fog, or cognitive impairment, can continue to persist for several months after the disease has passed.

Let us explore more about COVID-19 related brain fog.

What is COVID-19 Brain Fog and What Are Its Causes?

Brain fog is not a medical diagnosis, but it is a commonly used term to describe the feeling of being mentally slow, fuzzy, or just generally feeling spaced out. Some of the common symptoms of brain fog can include:

  • Lack of mental clarity
  • Memory problems
  • Confusion
  • Poor concentration
  • Feeling like you are ‘out of it.’

It is common for most people to experience periods of brain fog from time to time. You are likely to have felt mentally sluggish after not getting good sleep in the night or when you are under a lot of stress.

However, some of the people who have had COVID-19 have reported having brain fog that continued to last for several weeks to even months. The brain fog continued even after the other symptoms of COVID-19, like fatigue, cough, and shortness of breath went away.4

Researchers are still finding out what the potential cause of brain fog is in people who have had COVID-19, and it is believed that both psychological and physiological factors have a role to play.

The novel coronavirus (SARS-CoV-2) that causes COVID-19 is believed to spread through close contact with someone who already has the infection. Respiratory droplets from the infected person are able to enter the body through your mouth, nose, or eyes. Once the coronavirus enters your system, it starts to enter the cells through an enzyme known as the angiotensin-converting enzyme 2 (ACE2) receptor. The virus is known to be neuro-intensive, meaning it is able to enter your brain tissue as well.5

There have been several case studies that have discovered that some people who have had COVID-19 can develop complications like encephalopathy or altered consciousness.6 Encephalopathy is a general term that is used to refer to disease or damage of the brain.7

A recent January 2021 study found high levels of inflammatory cytokines in the fluid that surrounds the brains of people in the weeks after their COVID-19 infection.8

Cytokines are a type of molecule produced by your immune system and are known to promote inflammation.

Inflammation in the brain disrupts the ability of the neurons to communicate with each other, which is believed to be one of the factors that can contribute to brain fog.

Researchers have also identified certain microstructural changes in the hippocampus and other parts of the brain after the COVID-19 infection, and it is believed that these changes may also contribute to cognitive impairments.9

There can also be other factors that may contribute to COVID-19 brain fog. Inflammation in and around the brain can also contribute to brain fog. However, there are some other ways also that COVID-19 can indirectly cause brain fog. Some of the possible causes may include:

  • Depression
  • Feelings of loneliness
  • Poor quality of sleep
  • Dietary changes
  • Increased anxiety or stress
  • Reduced physical activity
  • Side effects of some medications

How Common is COVID-19 Brain Fog and How Long Does It Last? (H2)

Studies are still going on to understand how common brain fog is in people who have had COVID-19 infection.

For example, a recent study showed that around 7.5 to 31 percent of people experience an altered mental state as one of the symptoms of COVID-19 infection.10

However, this estimate was only based on small studies and might not be applicable to a larger population.

Another recent research report has discovered that neurological symptoms could actually be more common and widespread than previously believed and may occur in over 69 percent of people who have had a severe illness with the COVID-19 infection.11

As of now, though, it is not exactly clear why some people go on to develop brain fog, and others don’t develop it after a COVID-19 infection. People with serious cases of COVID-19 infection, though, seem to be at a much greater risk of developing neurological symptoms than people who have mild symptoms of the disease.12

In fact, severe brain-related complications such as seizure, delirium, and inflammation of the brain and the surrounding tissues are also common symptoms observed in critically ill COVID-19 patients.13

It is not really clear yet how long COVID-related brain fog tends to last for after the infection clears up. While some people have reported having brain fog that lingers on for weeks and even months after the respiratory symptoms have disappeared, others have reported experiencing brain fog only for a week to ten days.

A December 2020 study found that around 28 percent of people continued to have lingering problems with their concentration for more than 100 days after being admitted to the hospital for COVID-19.14

In another study, researchers discovered that out of a group of 60 participants who had recovered from COVID-19, almost 55 percent of them still continued to have neurological symptoms nearly three months after their disease. These symptoms included:

Can PTSD Cause COVID-19 Brain Fog?

A new report suggests that neurological symptoms like brain fog after COVID-19 could be due to post-traumatic stress disorder (PTSD).15

Studies have found that people who have recovered from COVID-19 may experience lingering difficulties in concentration, along with fatigue, anxiety, headaches, and sleep disruptions. Many patients start fearing that the infection has permanently damaged their brains, leading to more stress. However, researchers have said that there is unlikely to be any kind of permanent damage to the brain.

Researchers from UCLA and the Rosalind Franklin University of Medicine and Science have looked at the historical data from survivors of previous coronavirus infections, such as Severe Acute Respiratory Syndrome (SARS) and the Middle East Respiratory Syndrome (MERS). Reviewing the data from the MERS and SARS outbreaks showed that the survivors were at a greater risk for PTSD. In the case of COVID-19, the symptoms of PTSD could be present as a response to the invasive measures that are undertaken to treat the patients, including ventilation and intubation. This can be a traumatic experience for patients, enough to increase the risk of developing PTSD.16

In some cases, delirium can also cause patients with COVID-19 to experience hallucinations. The memory of this terrifying experience can also continue to plague the recovered patient, ultimately causing the neurological symptoms.

If the neurological symptoms are even partially due to a psychiatric condition like PTSD, treating the PTSD will help manage the neurological symptoms, and you can then continue to search for any underlying brain problems. While a PTSD diagnosis along with a diagnosis of COVID-19 is not good news, but there are several treatments for PTSD, including medications and psychotherapy.

Can COVID-19 Brain Fog Be Treated?

Currently, the best treatment for brain fog that is caused by COVID-19 is to have a healthy lifestyle. Here are some tips that may help improve your mental functioning if you are having ongoing brain fog after a COVID-19 infection.

  • Exercise Regularly: Regular physical activity is not only going to be beneficial for your lungs and heart, but it is also ideal for boosting your brain function.
  • Watch What You Eat: You should try to eat a well-balanced and healthy diet, even though your appetite might not be back to normal after the infection. Remember that a healthy diet gives your body the nourishment, energy, and strength it needs to get back to good health.
  • Get Plenty Of Sleep: Getting a good night’s sleep is important, and it will help your body heal, repair, and recover from the lingering effects of COVID-19.
  • Avoid Having Alcohol And Tobacco: Staying away from alcohol and tobacco products can help minimize the inflammation in your brain, thus helping reduce the brain fog.

Apart from all this, researchers are still continuing studies into COVID-19, and more and more information is emerging almost daily. Research is also looking at the potential benefit of steroids that can reduce the inflammation in the brain that is believed to be the cause of cognitive changes.

Should You See A Doctor For Your Brain Fog?

You should consider seeing your doctor if the cognitive/mental symptoms like brain fog become severe enough that they start interfering and disrupting your daily life. You should also see your doctor if your symptoms do not improve after a couple of weeks of getting the COVID-19 infection.

If you have been diagnosed with COVID-19, it is essential that you seek immediate medical assistance, especially if you have any of the following symptoms:

  • Rapid heart rate
  • Difficulty breathing
  • New mental confusion
  • Bluish lips or fingertips
  • Ongoing pain or pressure in the chest
  • Having trouble staying away
  • Difficulty waking up


Many people with COVID-19 infection have reported experiencing brain fog for several weeks or months after their respiratory symptoms have gotten better. It is believed that a combination of psychological factors and physiological changes in the brain contribute to COVID-19 related brain fog.

However, researchers are still trying to find out why some people go on to develop neurological symptoms of COVID-19 and others don’t. If you have been diagnosed with COVID-19 and you are experiencing some lingering cognitive symptoms that are affecting your ability to think clearly, along with confusion, it is important that you follow up with your doctor and let them know about these neurological symptoms.


  1. Johns Hopkins Coronavirus Resource Center. 2021. COVID-19 Map – Johns Hopkins Coronavirus Resource Center. [online] Available at: <> [Accessed 23 March 2021].
  2. Larsen, J.R., Martin, M.R., Martin, J.D., Kuhn, P. and Hicks, J.B., 2020. Modeling the Onset of Symptoms of COVID-19. Frontiers in public health, 8, p.473.
  3. Desai, I., Manchanda, R., Kumar, N., Tiwari, A. and Kumar, M., 2021. Neurological manifestations of coronavirus disease 2019: exploring past to understand present. Neurological Sciences, pp.1-13.
  4. Memorial Sloan Kettering Cancer Center. 2021. MSK Researchers Learn What’s Driving ‘Brain Fog’ in People with COVID-19. [online] Available at: <> [Accessed 23 March 2021].
  5. Montalvan, V., Lee, J., Bueso, T., De Toledo, J. and Rivas, K., 2020. Neurological manifestations of COVID-19 and other coronavirus infections: a systematic review. Clinical Neurology and Neurosurgery, 194, p.105921.
  6. Whittaker, A., Anson, M. and Harky, A., 2020. Neurological manifestations of COVID‐19: a systematic review and current update. Acta Neurologica Scandinavica, 142(1), pp.14-22.
  7. Filatov, A., Sharma, P., Hindi, F. and Espinosa, P.S., 2020. Neurological complications of coronavirus disease (COVID-19): encephalopathy. Cureus, 12(3).
  8. Remsik, J., Wilcox, J.A., Babady, N.E., McMillen, T.A., Vachha, B.A., Halpern, N.A., Dhawan, V., Rosenblum, M., Iacobuzio-Donahue, C.A., Avila, E.K. and Santomasso, B., 2021. Inflammatory leptomeningeal cytokines mediate COVID-19 neurologic symptoms in cancer patients. Cancer cell, 39(2), pp.276-283.
  9. Morley, J.E., 2020. COVID-19—the long road to recovery.
  10. Walitt, B. and Bartrum, E., 2021. A clinical primer for the expected and potential post-COVID-19 syndromes. Pain Reports, 6(1).
  11. Remsik, J., Wilcox, J.A., Babady, N.E., McMillen, T.A., Vachha, B.A., Halpern, N.A., Dhawan, V., Rosenblum, M., Iacobuzio-Donahue, C.A., Avila, E.K. and Santomasso, B., 2021. Inflammatory leptomeningeal cytokines mediate COVID-19 neurologic symptoms in cancer patients. Cancer cell, 39(2), pp.276-283.
  12. Mao, L., Jin, H., Wang, M., Hu, Y., Chen, S., He, Q., Chang, J., Hong, C., Zhou, Y., Wang, D. and Miao, X., 2020. Neurologic manifestations of hospitalized patients with coronavirus disease 2019 in Wuhan, China. JAMA neurology, 77(6), pp.683-690.
  13. Remsik, J., Wilcox, J.A., Babady, N.E., McMillen, T.A., Vachha, B.A., Halpern, N.A., Dhawan, V., Rosenblum, M., Iacobuzio-Donahue, C.A., Avila, E.K. and Santomasso, B., 2021. Inflammatory leptomeningeal cytokines mediate COVID-19 neurologic symptoms in cancer patients. Cancer cell, 39(2), pp.276-283.
  14. Garrigues, E., Janvier, P., Kherabi, Y., Le Bot, A., Hamon, A., Gouze, H., Doucet, L., Berkani, S., Oliosi, E., Mallart, E. and Corre, F., 2020. Post-discharge persistent symptoms and health-related quality of life after hospitalization for COVID-19. Journal of Infection, 81(6), pp.e4-e6.
  15. Kaseda, E.T. and Levine, A.J., 2020. Post-traumatic stress disorder: A differential diagnostic consideration for COVID-19 survivors. The Clinical Neuropsychologist, 34(7-8), pp.1498-1514.
  16. Blekas, A., Voitsidis, P., Athanasiadou, M., Parlapani, E., Chatzigeorgiou, A.F., Skoupra, M., Syngelakis, M., Holeva, V. and Diakogiannis, I., 2020. COVID-19: PTSD symptoms in Greek health care professionals. Psychological Trauma: Theory, Research, Practice, and Policy.

Also Read: