Can Covid Cause Anemia?
COVID-19 does more than affect the lungs. It can also trigger changes in the blood, including anemia. Yes, COVID-19 can cause anemia in some people, often linked to inflammation, low iron levels, or disruptions in red blood cell production.
This connection is important because anemia can make the body less able to carry oxygen, which may worsen other COVID-19 symptoms. Researchers have found that people with anemia may face more severe outcomes when infected with SARS-CoV-2. In some cases, the infection itself appears to lower hemoglobin levels or interfere with how the body uses iron.
These changes can show up during the illness or even weeks later in those experiencing long COVID. Understanding how coronavirus disease 2019 relates to anemia helps explain why some people feel ongoing fatigue, weakness, or shortness of breath after infection.
Definition of Symptom
A symptom is a sign or change in the body that suggests a possible health problem. In blood disorders, symptoms often point to issues with blood function, such as reduced red blood cell counts or changes in hemoglobin levels.
When anemia develops, the oxygen-carrying capacity of the blood decreases. This means the body cannot transport enough oxygen to tissues, which can create noticeable effects like fatigue or dizziness. Common symptoms linked to anemia include:
- Shortness of breath during activity or even at rest
- Tiredness that does not improve with rest
- Lightheadedness or fainting spells
- Pale skin or changes in nail and hair health
Doctors may measure blood markers such as mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). These values help identify the type of anemia and whether red blood cells are too small, too large, or carrying less hemoglobin than normal.
In cases connected to COVID-19, inflammation can disrupt oxygen transport by affecting how iron is used in the body. This can make symptoms of anemia more noticeable and may worsen existing health issues.
Possible Causes/Diseases Condition
COVID-19 can affect red blood cell production and function through several pathways. Inflammation plays a major role, as the immune system releases proteins that disrupt iron metabolism and limit hemoglobin production. This process often leads to anemia of inflammation or anemia of chronic disease.
Iron deficiency may also contribute. Some patients experience reduced iron absorption or loss of iron stores during illness. Without enough iron, the body cannot make healthy red blood cells, which may worsen fatigue and oxygen delivery.
In certain cases, COVID-19 has triggered hemolytic anemia, where red blood cells break down faster than the body can replace them. When this happens due to immune system activity, it becomes autoimmune hemolytic anemia. Autoantibodies may attack red blood cells, leading to lower hemoglobin levels.
Severe forms of COVID-19, including COVID-19 pneumonia, place extra stress on the body. Low oxygen levels and widespread inflammation can worsen anemia and increase the risk of organ injury. Research shows that patients with anemia often experience more severe illness and slower recovery. The table below highlights some related conditions:
| Condition | Possible Link with COVID-19 |
|---|---|
| Iron deficiency anemia | Reduced iron use or absorption |
| Hemolytic anemia | Destruction of red blood cells |
| Autoimmune hemolytic anemia | Autoantibodies attack red blood cells |
| Anemia of inflammation | Disrupted iron metabolism during infection |
| Severe COVID-19 with pneumonia | Higher risk of anemia and complications |
Other Non-Disease Causes
Not all cases of anemia linked to COVID-19 are due to the infection itself. Several non-disease factors can influence red blood cell levels and iron status, especially during recovery.
Iron metabolism and absorption can be disrupted by poor diet, limited appetite, or gut issues. If the body cannot absorb enough iron, anemia may develop even without active illness. Vitamin C helps here since it improves iron absorption from food and supplements.
Some patients may need iron supplements or even a blood transfusion if iron levels drop too low. These treatments help restore hemoglobin and support oxygen delivery. The choice depends on severity, underlying health, and whether the anemia existed before infection.
Certain COVID-19 treatments may also affect blood health. Drugs like ritonavir or remdesivir can cause side effects that influence red blood cell production or iron handling. While uncommon, these effects can add to the risk in patients with pre-existing anemia. Key factors that may contribute include:
- Low dietary iron intake.
- Reduced absorption in the gut.
- Medication side effects.
- Increased iron needs during recovery.
How It Causes the Symptom
COVID-19 can trigger inflammation in the body, releasing chemicals like interleukin-6 (IL-6) and tumor necrosis factor (TNF-alpha). These substances interfere with how your body uses iron and can reduce its ability to make hemoglobin, the protein in red blood cells that carries oxygen. As a result, levels of ferritin—a protein that stores iron—often rise, which is a sign of both inflammation and changes in iron storage.
The immune response can also change blood counts. Many patients develop low lymphocyte levels (a type of white blood cell important for fighting infections), shifts in platelet counts (cells that help with clotting), and high D-dimer levels, which indicate increased clotting activity. Another marker, lactate dehydrogenase (LDH), may be elevated, showing that tissues are under stress or that red blood cells are breaking down.
Oxidative stress—a type of damage caused by unstable molecules—also plays a role. Viral proteins, including the spike protein, may interact with red blood cell structures like CD147 and the band 3 protein. These interactions can damage cell membranes and lead to intravascular hemolysis, which means red blood cells break apart while still in the bloodstream.
When the immune system enters a cytokine storm (an extreme overreaction), large amounts of inflammatory signals disrupt normal blood function. This can make red blood cells more fragile by exposing certain molecules on their surface (phosphatidylserine) and releasing microparticles that mark them for removal. Key factors linked to COVID-related anemia include:
| Mechanism | Effect on Blood |
|---|---|
| IL-6 and TNF-alpha | Disrupt iron balance and reduce hemoglobin production |
| Ferritin | Elevated due to inflammation and iron storage changes |
| Oxidative stress | Damages red blood cells |
| Spike protein and CD147 | May weaken red blood cell membranes |
| Intravascular hemolysis | Direct destruction of red blood cells |
Together, these effects lower the body’s ability to carry oxygen, contributing to anemia in people with COVID-19.
Possible Complications
People with both COVID-19 and anemia may face more health risks than those with either condition alone. Low hemoglobin reduces oxygen delivery, which can worsen breathing problems already caused by the virus. This may increase the chance of needing hospital care. Common complications include:
- Severe respiratory distress due to poor oxygen supply
- Organ injury such as heart or kidney damage
- Higher risk of infections because of weakened immunity
COVID-19 can also trigger blood clotting problems. In some cases, this leads to thrombosis or pulmonary embolism, which can block blood flow and become life-threatening. Anemia may add strain to the cardiovascular system, raising the risk further. Inflammation from infection can disturb iron balance in the body. This may worsen anemia and contribute to fatigue, weakness, and delayed recovery.
In severe cases, patients may develop microangiopathic hemolytic anemia (MAHA), where red blood cells break down due to small blood vessel damage. This is more likely when clotting complications occur. The table below shows some possible outcomes linked to COVID-19 with anemia:
| Complication | Possible Effect |
|---|---|
| Respiratory distress | Worsened shortness of breath |
| Thrombosis | Blood clots in veins or arteries |
| Pulmonary embolism | Blocked blood flow in lungs |
| Organ injury | Heart or kidney damage |
| MAHA | Red blood cell destruction |
These complications highlight why patients with anemia and COVID-19 often need closer monitoring and medical support.
When to Seek Medical Attention
People with COVID-19 who notice signs of anemia should not ignore them. Common symptoms include unusual tiredness, shortness of breath, dizziness, or pale skin. If these symptoms appear or get worse during or after infection, contact a doctor. Certain warning signs need quicker attention. These include:
- Rapid heartbeat or chest pain
- Severe shortness of breath even at rest
- Fainting or near fainting
- Unexplained bleeding or bruising
Doctors may check hemoglobin, iron, vitamin B12, and folate levels with blood tests. These tests can show whether anemia is related to COVID-19, low nutrients, or another cause. People with long-term conditions like kidney disease, heart disease, or autoimmune disorders face higher risks and should call a doctor sooner if symptoms develop.
