If you have COVID-19, your symptoms may be relatively mild and manageable at home. That’s true for most people. But if you’re older or have another illness such as diabetes or heart disease, you’re more at risk for the serious form of COVID-19.
Some people -- about 1 in 6 -- will have complications, including some that are life-threatening. Many of these complications may be caused by a condition known as cytokine release syndrome or a cytokine storm. This is when an infection triggers your immune system to flood your bloodstream with inflammatory proteins called cytokines. They can kill tissue and damage your organs, including your lungs, heart, and kidneys.
COVID-19 complications may include the following.
Acute Respiratory Failure
When you have acute respiratory failure, your lungs might not pump enough oxygen into your blood or might not take enough carbon dioxide out. Both of these problems can happen at the same time.
Acute respiratory failure has been the leading cause of death for those who have died of COVID-19.
Pneumonia
Some who catch the new coronavirus get severe pneumonia in both lungs. COVID-19 pneumonia is a serious illness that can be deadly. When you have pneumonia, the air sacs in your lungs become inflamed, making it harder to breathe.
Images of very ill COVID-19 patients’ lungs show them filled with fluid, pus, and cell debris. In those cases, patients’ bodies weren’t able to transfer oxygen to the blood to keep their systems working properly.
Acute Respiratory Distress Syndrome (ARDS)
Acute respiratory distress syndrome (ARDS) was one of the most common complications of COVID-19.
With ARDS, the lungs are so severely damaged that fluid begins to leak into them. As a result, the body has trouble getting oxygen into the bloodstream. You may need mechanical help to breathe -- such as a ventilator -- until your lungs recover.
Acute Liver Injury
Most seriously ill patients run the greatest risk of liver damage. It's unclear whether the virus harms the liver or if it happens for another reason, but besides the lungs, the liver usually suffers the biggest injuries from COVID-19.
Acute liver injury and liver failure are life-threatening complications. (“Acute” means it happens suddenly.)
Acute Cardiac Injury
Many hospitalized with COVID-19 have developed heart problems, including arrhythmias and high levels of other cardiac ailments. But it’s not clear whether the virus itself affected patients’ hearts, or if the damage happened simply because the illness caused such stress on their bodies overall.
COVID-19 also may cause cardiac problems that last long after people have recovered from the coronavirus infection.
Secondary Infection
A secondary infection means that you get an infection unrelated to the first problem you had. In this case, it means someone with COVID-19 gets infected with something else.
Sometimes, a person fighting off, or recovering from, a virus gets infected by bacteria. Strep and staph are common culprits. This can be serious enough to raise the risk of death.
Acute Kidney Injury
This is not a common complication, but if it happens, it’s serious. If your kidneys stop working properly, doctors will start treatment to stop the damage. You might get dialysis (in which a machine filters your blood) until your kidneys get back to working normally. But sometimes, the damage doesn’t heal and people get chronic kidney disease, which would need to be managed long-term.
Septic Shock
Sepsis happens when your body’s reaction to an infection misfires. The chemicals released into your bloodstream to battle the illness don’t trigger the right response, and instead your organs are damaged. If the process isn’t stopped, you can go into what’s called septic shock. If your blood pressure drops too much, septic shock can be fatal.
Disseminated Intravascular Coagulation
When you have disseminated intravascular coagulation, or DIC, the body’s blood-clotting response doesn’t work right. Abnormal clots form, which can lead to internal bleeding or organ failure.
DIC is not uncommon among those who have died or COVID.
Blood Clots
A condition called disseminated intravascular coagulation (DIC) causes your body’s blood-clotting response to work differently than it should. Unusual clots form, which can lead to internal bleeding or organ failure and death.
Those hospitalized with COVID have been found to be more likely to develop clots than those hospitalized with the flu. Some were in patients’ legs (deep vein thrombosis or DVT), lungs (pulmonary embolism or PE), or arteries. But none of the patients had DIC.
COVID-19-associated coagulopathy (CAC) is a life-threatening condition caused by the virus. It’s marked by different protein levels in your blood than the ones caused by DIC.
Multisystem Inflammatory Syndrome in Children
A number of children and teens have been hospitalized with a condition called multisystem inflammatory syndrome in children (MIS-C) or pediatric multisystem inflammatory syndrome (PMIS) It is linked to the new coronavirus. Symptoms include fever, belly pain, vomiting, diarrhea, rash, headache, and confusion. They’re similar to those of toxic shock syndrome or Kawasaki disease, which causes inflamed blood vessels in children.
Chronic Fatigue
Some people who’ve had COVID-19 develop a condition similar to chronic fatigue syndrome. They may have a brain fog, severe fatigue, pain, trouble thinking, or dizziness.
Rhabdomyolysis
This is an extremely rare condition, but it’s one COVID-19 researchers are watching. In rhabdomyolysis, your muscles break down and tissue dies. As cells fall apart, a protein called myoglobin floods your bloodstream. If your kidneys can’t flush it out of your blood quickly enough, it can overwhelm them and cause death.