Long term effects of COVID-19

It has been more than five years since much of the world went into a collective lockdown for the acute portion of the COVID-10 pandemic. Whether people want to admit it or not, it has changed us forever. There was so much we did not know back then about the virus, the infection and the aftermath. In the past five years, doctors and researchers have been able to collect and interpret A LOT of data on the long term effects of COVID-19 infections.

For many people, COVID-19 symptoms don’t end when the virus clears. Conditions like chronic fatigue and brain fog are commonly recognized as part of long Covid—a condition defined by symptoms that persist for at least three months after infection. It is estimated that around 400 million people worldwide have experienced some form of long Covid.

The long term effects of Covid-19 extend beyond what’s officially classified as “long Covid.” The virus can also cause lasting damage to organs, such as the lungs and heart, as well as disrupt the gut microbiome. These changes may not always be labeled as long Covid, but they can still impact overall health after the initial infection. As research is continuing to show that Covid has wide-ranging effects on multiple systems in the body. Acknowledging these long-term consequences is important for developing treatment as well as supporting those experiencing symptoms and new conditions long after infection.

Lung Health

Most people are aware that Covid-19 is a respiratory virus and can cause coughing, congestion, sore throat and sometimes pneumonia. When Covid-19 infects the body, it targets cells along the airways, triggering inflammation that can damage or even destroy healthy lung tissue. This disruption affects the lungs' ability to efficiently deliver oxygen to the rest of the body. The virus irritates lung tissue, leading to persistent symptoms such as shortness of breath and chronic coughing. In some cases, Covid can progress to pneumonia, resulting in scarring and small tissue nodules scattered throughout the lungs. These scars, also known as fibrosis can reduce lung function, making it more difficult to breathe. As the lungs work to heal, they form scar tissue. The scarring or fibrosis can make the lungs stiff and reduce their capacity. This can lead to lingering symptoms such as persistent coughing and shortness of breath.

Emerging research suggests that the impact can be long-lasting. Fibrosis in the lungs is not reversible. Some studies indicate that more than 10% of individuals who were hospitalized with Covid still experience lung scarring and related complications even two years after infection. While more research is needed to understand the specifics, these findings highlight the importance of trying to avoid and prevent catching Covid as well as monitoring lung health following a Covid infection.

Gut Health

While Covid-19 is often associated with respiratory symptoms, it can also affect the digestive system, causing nausea, vomiting, and diarrhea. For some people with long Covid, these symptoms do not go away. Covid has been linked to long-term gastrointestinal problems such as acid reflux, constipation, chronic diarrhea, and persistent abdominal pain. These issues can linger for months or even years after the initial infection.

A 2024 study found that Covid left around 10% of people struggling with ongoing abdominal pain and 13% dealing with other lasting gastrointestinal issues a year later. Researchers are still understanding exactly why Covid-19 can have such a profound effect on the digestive system. One major factor appears to be the virus’s impact on the gut microbiome—bacteria and microbes that help regulate digestion and immune function. Studies show that Covid can reduce beneficial gut microbes while increasing harmful ones. Since “good” bacteria help control inflammation, an imbalance in the microbiome can lead to widespread digestive issues.

Beyond microbiome disruption, Covid-related inflammation may also damage the intestinal lining, allowing toxins and undigested food particles to escape into the body. This can trigger immune responses similar to allergies, potentially leading to new food intolerances.

Additionally, inflammation can damage the nerves that control digestion and signal pain. This could result in abdominal discomfort, erratic intestinal contractions, and irregular digestion—causing food to move too quickly (leading to diarrhea) or too slowly (resulting in constipation).

While more research is still being done, current findings highlight how Covid’s impact extends beyond the lungs, potentially reshaping gut health long after the initial infection.

Brain Health

Covid-19 can also take a toll on the brain. During an active infection, many people experience headaches, dizziness, loss of taste and/or smell and mental confusion. Some struggle to find the right words, have trouble concentrating, or notice lapses in their memory. These same issues can continue beyond the viral infection of Covid-19. Studies suggest that around 20 to 30% of people still experience brain fog at least three months after their initial infection. This lingering mental cloudiness can make everyday tasks—like following a conversation or staying focused at work—much more challenging.

Beyond brain fog, research has also linked Covid to an increased risk of anxiety, depression, and the worsening of existing mental health conditions. As scientists continue to study these effects, it’s clear that Covid’s impact on the brain can be long-lasting, underscoring the need for greater awareness and support for those dealing with post-Covid cognitive and mental health challenges.

Scientists are still uncovering the full extent of Covid-19’s impact on the brain, but one key factor stands out: persistent inflammation. When the body remains inflamed after an infection, it can damage neurons and disrupt communication between brain cells. This may contribute to symptoms like brain fog, memory issues, and difficulty with concentration.

Some researchers believe that certain areas of the brain—especially those responsible for cognition and emotion—are particularly vulnerable to this inflammation. This could explain why Covid is linked not only to cognitive struggles but also to conditions like anxiety and depression, or the worsening of existing mental health disorders. Another possibility that is being investigated is damage to the blood-brain barrier, a protective shield that helps maintain brain function. If Covid weakens this barrier, harmful substances could reach brain tissue and contribute to cognitive decline.

Additionally, some scientists suspect that remnants of the virus may linger in the brain long after the initial infection, potentially driving ongoing neurological symptoms. As research continues, it’s becoming clear that Covid’s effects on the brain can be long-lasting, highlighting the need for better treatments and support for those struggling with post-Covid cognitive challenges.

Circulation and Energy Levels

Fatigue and shortness of breath are commonly experienced in long Covid. It is likely that they are due to circulatory issues. Research shows that some patients struggle to move blood efficiently from their legs and abdomen back to the heart. As a result, the heart pumps out less blood, leading to exhaustion, breathlessness, and a general feeling of unwellness, especially after physical activity.

Scientists are still working to understand why this happens, but one leading theory points to inflammation damaging key nerve fibers outside the brain and spinal cord. These nerves play a crucial role in controlling how blood vessels contract and push blood through the body. If they are not functioning properly, circulation can become stagnant and slow. While more detailed research is needed, these findings highlight how long Covid extends beyond the lungs, impacting the body's ability to maintain proper blood flow and can effect energy levels. Understanding these effects may help lead to better treatments for those struggling with post-Covid circulatory issues.

Preservation of Health, Prevention of Illness

Knowing the potential long term effects of a Covid-19 infection makes a great case to prevent catching it at all. As a Chinese Medicine doctor, I try to focus on education for prevention. Preserving your health and preventing illness is the main concern in Chinese and other Eastern medicines. The Western medical system does not focus on this as much because it is generally not as feasible in our societies. In the United States, our health care decisions are often dictated by our ability to access or pay for care. This often leads to a culture of letting certain health concerns go until they get bad enough and/or until you have the time to address them. This is not truly a preventative model of care. I highlight this because I have seen too many long Covid patients struggle with how drastically different they must live their lives and it cannot be easy.Doctors are still figuring out how to handle some of the consequences of long Covid today, which can make it frustrating if you’re someone trying to seek care or treatment. It is almost as if there really is not treatment right now. In the meantime, some of the easiest things you can do is to improve air circulation indoors and use well fitted masks when indoors or in higher risks situations.

For my regular patients, if you think you have caught covid or have been knowingly exposed, please reach out as soon as possible for an herbal consult. Please do not wait until you’ve had symptoms for days. Getting herbal treatment within in the first 24 hours can make a big difference!

You might also be interested in reading: 5 (more) Chinese Herbs for Coughing, 5 Benefits of Echinacea, POTS and Long Covid

Written by Dr. Emily Siy, DACM on 3/17/25

Sources

Blum, D., Agrawal, N., Callahan, A. (2025) A Clearer Picture of Covid’s Lasting Effects on the Body The New York Times March 10

Lung Health

Gut Health

Brain Health

Circulation and Energy Levels

Preservation of Health, Prevention of Illness

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