Written by Dr. Savannah Muncy, Pharm.D on
September 6, 2022
Reading Time: 6 minutes

Medically Reviewed by our Medical Affairs Team

Written by Dr. Savannah Muncy, Pharm.D on:

Have you been experiencing brain fog since getting the vaccine? You’re not alone.

In this article, we’ll discuss what brain fog is, the symptoms of brain fog, and how vaccines can cause it.

We’ll also provide some tips on how to improve your brain health and reduce the risk of experiencing brain fog from vaccines.

Let’s get started.

What is brain fog, exactly?

Brain fog is a general term used to describe feelings of confusion, forgetfulness, and mental fatigue.

You may feel like you can’t think clearly or concentrate on tasks as well as you could before. It can also make it difficult for you to perform even simple everyday activities.

Brain fog can be a frustrating and even debilitating condition. It can impact your work, school, and social life.

Fortunately, there are things you can do to improve your brain health and reduce the risk of experiencing brain fog from vaccines—more on that later.

Common Causes of Brain Fog

There are many possible causes of brain fog.

It can be caused by a lack of sleep, an unhealthy diet or poor nutrition, dehydration, stress, mental health conditions, lack of physical activities, underlying health conditions, and more.

Certain medical conditions can also lead to brain fog, including thyroid problems, autoimmune diseases, hormonal imbalances, and Lyme disease.

Vaccines can also cause brain fog. In fact, vaccines are one of the most common causes of brain fog, but more on that later.

Common Symptoms

Brain fog can cause a variety of symptoms, including:

  • fatigue
  • difficulty concentrating
  • forgetfulness
  • confusion
  • difficulty thinking clearly
  • mental exhaustion
  • mood swings
  • irritability
  • headaches
  • dizziness
  • poor balance
  • trouble sleeping,
  • and more.

These symptoms can range from mild to severe. They may come and go, or they may be constant. Brain fog can make it difficult to perform even simple tasks, like grocery shopping or paying bills.

If you’re experiencing any of these symptoms, it’s important to see a doctor to rule out other potential causes.

What are vaccines, exactly?

Vaccines are products that help protect against infections.

They work by injecting a person with a “dead” or “modified” form of the virus. As that person’s immune system fights off the fake infection, they also develop immunity to the real thing.

Vaccines have been used for centuries to help prevent deadly diseases, such as smallpox, polio, and measles.

Today, vaccines are still used to protect against infections. However, they can also cause side effects, including brain fog.

Vaccine Side Effects

Most vaccines are safe and effective, but they can cause side effects. The most common side effects are mild and include:

  • soreness, redness, or swelling at the injection site
  • fever or chills
  • rashes
  • body aches
  • muscle pain
  • headache
  • fatigue
  • nausea or vomiting
  • rare severe reactions

These side effects usually go away on their own after a few days. However, some vaccines can cause more serious side effects, including brain fog.

Why do vaccines cause brain fog?

Vaccines cause brain fog because they contain adjuvants.

Adjuvants are substances that help increase the effectiveness of vaccines. They work by stimulating the immune system to produce more antibodies.

While this helps protect against infections, it can also lead to side effects, including brain fog.

Adjuvants are found in most vaccines, but they’re more likely to cause side effects in certain vaccines, such as the flu vaccine.

The flu vaccine contains an adjuvant called squalene.

Squalene is a type of oil that’s found naturally in the body. It’s also used in cosmetics and skincare products.

When squalene is injected into the body, it can cause an immune reaction. This can lead to side effects, such as brain fog.

Squalene is just one example of an adjuvant that can cause brain fog. There are many others, and they’re found in vaccines for both adults and children.

If you’re concerned about the adjuvants in vaccines, talk to your doctor or a certified immunization specialist. They can help you make an informed decision about which vaccines are right for you.

Common Types of Vaccines that Cause Brain Fog

There are many types of vaccines that can cause brain fog. Some of the most common vaccines that contain adjuvants include:

Influenza vaccines

Influenza vaccines, also called “flu shots,” are immunizations that protect against the four influenza viruses that scientists predict will be most prevalent during the upcoming season—fall and winter.

Most flu vaccines are shot injections, although a nasal spray version is also available. The flu shot contains an adjuvant called squalene.

When squalene is injected into the body, it can cause an immune reaction. This can lead to side effects, such as brain fog.

Human papillomavirus vaccines

Human papillomavirus (HPV) vaccines are immunizations that protect against infection with HPV, a virus that can cause cancer.

There are two types of HPV vaccines: Gardasil and Cervarix.

Gardasil is approved for use in males and females ages nine through 26.

Cervarix is only approved for use in females ages nine through 25.

Both vaccines are given as a series of three shots over six months.

Gardasil contains an adjuvant called AS04. AS04 is a combination of aluminum hydroxide and MPL.

Cervarix contains an adjuvant called AS03. AS03 is a combination of aluminum hydroxide and CpG 7909.

When these adjuvants are injected into the body, they can cause an immune reaction. This can lead to side effects, such as brain fog.

Meningococcal vaccines

Meningococcal vaccines are immunizations that protect against infection with the meningococcus bacteria. There are two types of meningococcal vaccines: MenACWY and MenB.

MenACWY vaccines are given to people ages 11 through 18 as a series of two shots, given two to six months apart.

MenB vaccines are given to people ages 16 through 23 as a series of three shots, given two to six months apart.

Both vaccines can cause side effects, including brain fog.

Pneumococcal vaccines

Pneumococcal vaccines are immunizations that protect against infection with the pneumococcus bacteria. There are two types of pneumococcal vaccines: PCV13 and PPSV23.

PCV13 vaccines are given to people ages six weeks through 64 years as a series of four shots, given at two, four, six, and 12 to 15 months old.

PPSV23 vaccines are given to people ages two years and older as a single shot.

PPSV23 vaccines can cause side effects, including brain fog.

Pertussis vaccines

Pertussis vaccines are immunizations that protect against infection with the pertussis bacteria. There are two types of pertussis vaccines: DTaP and Tdap.

DTaP vaccines are given to people ages six weeks through 64 years as a series of five shots, given at two, four, six, and 12 to 15 months old.

Tdap vaccines are given to people ages 11 through 64 years as a single shot.

Both vaccines can cause side effects, including brain fog.

Hepatitis B vaccines

Hepatitis B vaccines are immunizations that protect against infection with the hepatitis B virus. There are two types of hepatitis B vaccines: Engerix-B and Recombivax HB.

Engerix-B vaccines are given to people ages six weeks through 64 years as a series of three shots, given at two, four, and six months old.

Recombivax HB vaccines are given to people ages 11 through 64 years as a series of three shots, given at two, four, and six months old.

Both vaccines can cause side effects, including brain fog.

Covid-19 vaccines

Covid-19 vaccines are immunizations that protect against infection with the novel coronavirus that has spread worldwide since December 2019.

Some people who received the Covid-19 vaccine felt brain fog and fatigue; this is due to the body’s immune response to the vaccine.

When the body’s immune system is fighting off a virus or a weak copy of the virus, it can lead to side effects such as brain fog.

These are just a few examples. There are many other vaccines that contain adjuvants, so it’s important to talk to your doctor about the risks and benefits of each vaccine.

Preventing Brain Fog from Vaccines

There are a few things you can do to prevent brain fog from vaccines.

First, make sure to talk to your doctor about the risks and benefits of each vaccine. This is especially important if you have a history of allergies or autoimmune diseases.

Second, ask your doctor if there’s an adjuvant-free version of the vaccine. Adjuvant-free vaccines are available for some vaccines, such as the flu vaccine.

Third, consider waiting to get vaccinated until you’re feeling well. If you’re already sick, your immune system may be weak. This can make it more likely that you’ll experience side effects from vaccines.

Fourth, take care of yourself after you get vaccinated. Get plenty of rest and drink lots of fluids. This will help your body recover from the vaccine and reduce your risk of side effects.

Finally, talk to your doctor if you experience any side effects from vaccines. They can help you manage the side effects and make sure they don’t cause any long-term problems.

In Conclusion

Vaccines are an important part of protecting your health. However, they can sometimes cause side effects, including brain fog.

There are a few things you can do to prevent brain fog from vaccines. Make sure to talk to your doctor about the risks and benefits of each vaccine. You can also ask your doctor if there’s an adjuvant-free version of the vaccine.

If you’re already sick, you may want to wait to get vaccinated until you’re feeling well. And after you get vaccinated, take care of yourself and get plenty of rest.

If you want to learn more about fighting brain fog and improving your overall brain health in the long run, check out these helpful resources we compiled on our blog.

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