Most people probably don’t think about blood clots regularly. But with reports of a small number of people developing blood clots after receiving either the Johnson & Johnson or the AstraZeneca COVID-19 vaccine, many people are now wondering what the warning signs are.
There are several different variations of blood clots, each with its own set of red flags and options for treatment. They can form for several reasons, including medication, lifestyle factors, and other health conditions, and they can occur in different parts of the body.
All that said, blood clots can cause severe harm or be fatal if left unaddressed. If you’re concerned ― whether it’s because of a vaccine or, more likely, something else ― read on for the signs to pay attention to and advice on what to do if you think you’re at risk.
Symptoms Of Blood Clots
Blood clots can originate in the veins or arteries. There are two main types of blood clots to be aware of, and each can lead to its own set of potential complications. One type is called a thrombus, which is a stationary clot. These block blood flow in the part of the body where the clot occurs. Another type, called an embolus, is a blood clot that can break loose. These are particularly dangerous because they can travel to other parts of the body ― like the heart or the lungs ― and cause severe damage.
The symptoms of blood clots vary depending on the type. When the clot is stationary, like deep vein thrombosis (a lump in your leg), you may experience:
- Warmth and redness where the lump is located ― typically in the leg or the arm
- Pain near the site of the clot
- Numbness or weakness
- A change in your mental state
If the clot has traveled, leading to complications like a pulmonary embolism (a clot that has moved to your lungs), you may experience symptoms including:
- Sudden shortness of breath
- A cough, with or without blood
- Clammy, pale, or blue skin
- Excessive sweating
- Nausea or vomiting
Blood clots can affect your arms, legs, heart, lungs, kidneys, and brain, depending on where they form and where they travel in the bloodstream. A handful of people who received the Johnson & Johnson vaccine developed complications from a clot originating in the veins near the brain, called cerebral venous sinus thrombosis, or CVST. This issue is seen in combination with low levels of blood platelets.
(A few people who received the AstraZeneca shot experienced clots caused by the same issue, but since the AstraZeneca dose isn’t yet approved for use in the United States, this story will focus on J&J.) According to the Centers for Disease Control and Prevention and the Food and Drug Administration, symptoms associated with this type of clot complication include severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination.
A few important notes when it comes to the J&J vaccine: Blood clots following the shot appear to be extremely rare ― as of now, there are only six reported cases out of nearly 7 million doses of the vaccine that have been distributed ― and have occurred within 13 days of vaccination. You have a higher risk of developing blood clots from actual COVID-19 infection.
“Just remember that COVID-19 causes blood clots,” infectious disease expert Amesh Adalja told HuffPost for a separate story. “And COVID-19 causes blood clots at a higher rate than the vaccine does.” Experts emphasize that the vaccine could be a game-changer for the pandemic, and a principal reason for the pause in distribution is to inform health care providers how to spot, treat and report the issue. Don’t let this deter you from getting any vaccination against the coronavirus.