Key TakeawaysEnlarged lymph nodes in the armpit are normal after any vaccination and are a sign that the body’s immune system has responded to the vaccine.After a person gets a COVID-19 vaccine, enlarged lymph nodes can show up on mammograms days or even weeks later.People should not skip their regular screening mammogram because of receiving the COVID-19 vaccine, but it might help to schedule it for several weeks after they get the shot.Patients may need to undergo additional ultrasonography to ensure that the enlarged nodes have returned to normal and that there are no other issues with the breast image.

Key Takeaways

Enlarged lymph nodes in the armpit are normal after any vaccination and are a sign that the body’s immune system has responded to the vaccine.After a person gets a COVID-19 vaccine, enlarged lymph nodes can show up on mammograms days or even weeks later.People should not skip their regular screening mammogram because of receiving the COVID-19 vaccine, but it might help to schedule it for several weeks after they get the shot.Patients may need to undergo additional ultrasonography to ensure that the enlarged nodes have returned to normal and that there are no other issues with the breast image.

After you get a vaccine of any kind, including a COVID-19 shot, yourlymph nodes—especially those under your arm—can get bigger as your immune system responds. While these enlarged lymph nodes are normal after a vaccine, they can sometimes be mistaken for malignancies on imaging tests like a mammogram.

What Is a Mammogram?

Mammograms After COVID-19 Vaccines

An article published in the journalClinical Imagingin January reported on four cases involving people who had anomalous readings on a mammogram after they got aCOVID-19 vaccine.

In two cases, the person was having a regular screening mammogram, one person was having a follow-up mammogram for an issue with the breast, and the fourth person was being evaluated afterfeeling a lumpin their left armpit. In all four cases, breast imaging showedenlarged or swollen lymph nodesin the armpit.

Enlarged lymph nodes in the armpit are also known ashyperplastic axillary adenopathy.

Three of the four people had received their first dose ofPfizer-BioNtech’s COVID-19 vaccinefive to nine days before their mammogram. The fourth person had their first dose ofModerna’s vaccine13 days before their mammogram.

In all four cases, the people had been vaccinated in the left arm and the enlargedlymph nodeswere seen in the left armpit. None of the four people had a history of breast cancer.

Mammogram Images: Normal vs. Abnormal

Vaccines Can Cause Swollen Lymph Nodes

Dana Smetherman, MD, chair of the Commission on Breast Imaging with the American College of Radiology and chair of radiology at Oschner Health in New Orleans, tells Verywell that swollen lymph nodes after a vaccine are actually normal, and “a sign our body is producing animmune response.”

Smetherman says that enlarged lymph nodes occur in 11 to 12% of all people after the first dose of the COVID-19 vaccine. About 16% develop enlarged nodes after they get the second dose of vaccine.

Enlarged lymph nodescan also happen after other vaccinations, such as theHPV vaccineorflu shots, but Smetherman says the situation with COVID-19 vaccines is a little different “because we’re all getting this vaccine together at the same time.”

Benign Breast Changes Can Look Like Cancer

More People Getting Vaccines

In December, the Biden Administration announced itsgoal of administering 100 million COVID-19 vaccines during its first 100 days. According to the Centers for Disease Control and Prevention’s COVID-19 Vaccine Tracker, 64,177,474 doses have been administered in the U.S. as of February 22.

According to the CDC, more than 65% of women over age 40 in the United States had a mammogram in the last two years.

Many peoplegetting a vaccinewill also have a mammogram scheduled within days or weeks of their shot. This has created a somewhat unusual situation—before the pandemic, it would have been less likely for someone to have a vaccination and a mammogram close together.

Clinicians Must Stay Abreast of Vaccine Side Effects

The authors of the case report study said that radiologists should keep the potential side effect of the vaccine in mind when viewing breast images.

Dana Smetherman, MDThis is not a reason to delay the vaccine or to delay the screening mammogram.

Dana Smetherman, MD

This is not a reason to delay the vaccine or to delay the screening mammogram.

Clinicians will need to determine if a patient has recently been vaccinated at the time of the mammogram to ensure that appropriate follow-up care is conducted as well as avoid unneeded invasive tests like abiopsy of the lymph nodes.

Don’t Delay Your Shot—or Your Mammogram

“It is very important to stress that this is not a reason to delay the vaccine or to delay the screening mammogram,” Smetherman says. “We want lots and lots of people to get these vaccines.”

Even still, many people did not get a mammogram orother preventive carelast year, citing concerns about the pandemic. “We may have been quarantining, but diseases like breast cancer were not," Smetherman says.

‘Mammograms Saved My Life’: Why Breast Cancer Screenings During COVID-19 Matter

If possible, schedule an annual mammogram before you get vaccinated or wait to have a mammogram done four to six weeks after you get your second dose. If it’s not possible to stagger the scheduling, it’s important to still get your shot and your mammogram.

Dana Smetherman, MDWe may have been quarantining, but diseases like breast cancer were not.

We may have been quarantining, but diseases like breast cancer were not.

The Society of Breast Imaging has guidelines for what to do if an enlarged node or other changes in the lymph glands are seen on a mammogram. “If nothing else in the breast looks abnormal, what we do is schedule a follow-up ultrasonography of the breast in a month or two just to see if those swollen lymph nodes go away," Smetherman says.

It’s also important to note that swollen lymph nodes can be a sign of many illnesses and are not specific to breast cancer or other inflammatory changes. Even if you don’t see an enlarged lymph node, it can often be felt. “If you happen to feel it a few days after you had your vaccine, I would wait a couple of weeks to see if goes away," Smetherman says.

If your swollen node does not go away in a few weeks, let your healthcare provider know.

What This Means For YouYou may experience swollen or enlarged lymph nodes after getting either dose of the COVID-19 vaccine. If you have a mammogram scheduled within a few days or weeks of getting your shot, they could show up on the mammogram and be confused for something else.If you are able to put off your mammogram until a few weeks after you get your shot, it will make it less likely that there will be confusion. However, if you can’t change your appointment, you should still get your mammogram as scheduled. Just be sure to tell your doctor or the radiologist that you recently had a COVID-19 vaccine.

What This Means For You

You may experience swollen or enlarged lymph nodes after getting either dose of the COVID-19 vaccine. If you have a mammogram scheduled within a few days or weeks of getting your shot, they could show up on the mammogram and be confused for something else.If you are able to put off your mammogram until a few weeks after you get your shot, it will make it less likely that there will be confusion. However, if you can’t change your appointment, you should still get your mammogram as scheduled. Just be sure to tell your doctor or the radiologist that you recently had a COVID-19 vaccine.

You may experience swollen or enlarged lymph nodes after getting either dose of the COVID-19 vaccine. If you have a mammogram scheduled within a few days or weeks of getting your shot, they could show up on the mammogram and be confused for something else.

If you are able to put off your mammogram until a few weeks after you get your shot, it will make it less likely that there will be confusion. However, if you can’t change your appointment, you should still get your mammogram as scheduled. Just be sure to tell your doctor or the radiologist that you recently had a COVID-19 vaccine.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit ourcoronavirus news page.

3 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Mehta N, Sales RM, Babagbemi K, Levy AD, McGrath AL, Drotman M, et al.Unilateral axillary adenopathy in the setting of COVID-19 vaccine.Clinical Imaging. 2021;75:12-15. doi:10.1016/j.clinimag.2021.01.016Centers for Disease Control and Prevention.COVID-19 vaccinations in the United States.Centers for Disease Control and Prevention, National Center for Health Statistics.Mammography.

3 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Mehta N, Sales RM, Babagbemi K, Levy AD, McGrath AL, Drotman M, et al.Unilateral axillary adenopathy in the setting of COVID-19 vaccine.Clinical Imaging. 2021;75:12-15. doi:10.1016/j.clinimag.2021.01.016Centers for Disease Control and Prevention.COVID-19 vaccinations in the United States.Centers for Disease Control and Prevention, National Center for Health Statistics.Mammography.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Mehta N, Sales RM, Babagbemi K, Levy AD, McGrath AL, Drotman M, et al.Unilateral axillary adenopathy in the setting of COVID-19 vaccine.Clinical Imaging. 2021;75:12-15. doi:10.1016/j.clinimag.2021.01.016Centers for Disease Control and Prevention.COVID-19 vaccinations in the United States.Centers for Disease Control and Prevention, National Center for Health Statistics.Mammography.

Mehta N, Sales RM, Babagbemi K, Levy AD, McGrath AL, Drotman M, et al.Unilateral axillary adenopathy in the setting of COVID-19 vaccine.Clinical Imaging. 2021;75:12-15. doi:10.1016/j.clinimag.2021.01.016

Centers for Disease Control and Prevention.COVID-19 vaccinations in the United States.

Centers for Disease Control and Prevention, National Center for Health Statistics.Mammography.

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