It may seem like the last few years of the COVID-19 pandemic have dragged on, but infection and vaccinations are still relatively new, and more is being learned about the virus and its full effects every day.

When vaccines to fight the virus were released in late 2020, they came with the promise of reducing severe infection. But for some people, the vaccine raised even more questions.

Some people were reporting breast pain after vaccination. In addition, changes in the shape and size of the lymph nodes in the armpit (axillary area) began appearing on mammogram screenings.

This article will explore how the COVID-19 vaccine can cause breast pain and changes to a mammogram, why you shouldn’t delay your mammogram after a COVID-19 vaccine, and when you need to worry about breast pain.

In the months after the COVID-19 vaccines became available, people who’d been vaccinated — particularly women — began reporting breast pain or swelling and pain near their armpits.

This pain often only appeared after vaccination and usually in the breast that was on the same side of the body that the vaccine was given.

Breast pain after COVID-19 vaccine

When this side effect was first reported, it was suspected to be caused by a normal immune reaction to the vaccine.

This side effect happens — although rarely — with other types of vaccines, too, but was reported more frequently after COVID-19 vaccination.

Your lymph nodes are part of the immune system and help collect and destroy bacteria and other problematic invaders like cancer cells. Swelling of the lymph nodes near the breasts isn’t common outside of being a breast cancer symptom, so the appearance of this as a side effect caused initial alarm.

Mammogram abnormalities after COVID-19 vaccine

A COVID-19 vaccination may change the shape and size of lymph nodes in the armpit area.

In the beginning, women were advised to delay mammograms and other breast cancer screenings by 4 to 6 weeks after vaccination in order to avoid unnecessary concern over this side effect. However, it quickly became clear that the swelling that developed after the vaccine could take months to resolve.

In one case study from Japan, a woman was still experiencing swelling of the lymph node in the breast on her vaccinated side 6 months after it first appeared.

Given the risk of waiting or delaying routine breast examinations and screenings (especially if you’re at higher risk), it’s now recommended that mammograms and other screenings not be delayed following a COVID-19 vaccination.

However, don’t be surprised if you’re asked about whether you received a COVID-19 vaccine and when during a screening mammogram. This is because your radiology technician may notice a change in the size or shape of your lymph node from previous screenings.

Additional images may also be collected to confirm any findings are vaccine-related and not due to any other problems.

Don’t delay breast cancer screenings after a COVID-19 vaccination

Don’t delay breast cancer screenings or mammograms after a COVID-19 vaccination. Also, be sure to tell your mammogram technician when and in which arm you received your COVID-19 vaccine when you arrive for a screening mammogram, especially if you have a history of breast cancer or you’re considered at high risk.

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It’s not likely that you — or even your doctor — will be able to tell the difference between vaccine side effects, breast cancer, or other causes of breast pain with the naked eye.

Imaging studies like mammograms and ultrasounds are usually used to examine what is under the surface of your breast tissue. In many cases, breast cancer develops with few or no symptoms, so a sore armpit or breast pain may come from a variety of other causes.

When symptoms do appear with breast cancer, they usually include:

  • a new lump that you can feel in your breast or armpit
  • thickened skin or swelling in your breast
  • dimpling of the skin on your breast
  • irritation or redness on the skin of your breast
  • changes in the texture or shape of your nipple
  • flaky skin on the breast or nipple
  • discharge from your nipple that isn’t breast milk
  • changes in the shape or size of your breast
  • breast pain

Beyond vaccinations or breast cancer, there are a number of factors that can cause breast pain, tenderness, or soreness. These include:

Is breast pain caused by COVID-19?

Breast pain isn’t necessarily a symptom of COVID-19 or long-COVID, but you may have muscular or respiratory pain that you may feel in your breasts or chest.

Breast pain is usually associated with COVID-19 vaccines and is a somewhat expected effect as the lymph nodes in your armpit launch an immune response to the vaccine.

Is breast pain a long-term side effect of the COVID-19 vaccine?

Breast pain and underarm pain should eventually go away after your vaccine, but it can last up to several months. If you have pain or soreness that isn’t improving or is getting worse after your vaccine, see a doctor to rule out other causes.

What are all the side effects of the COVID-19 vaccine in women?

Both men and women may experience lymph node soreness in the armpit after a COVID-19 vaccine. Beyond that, other side effects of the vaccine for both men and women may include:

  • redness or swelling at the injection site
  • fatigue
  • headaches
  • muscle pain
  • chills
  • fever
  • nausea

Should you reschedule your mammogram after a COVID-19 vaccine?

No. You shouldn’t delay a mammogram because of COVID-19 vaccination, but you should tell your technician when and in which arm you received your vaccine injection.

The COVID-19 vaccine triggers a response in your immune system to protect you against COVID-19 infection. This response could cause other side effects like soreness in the lymph nodes located in your armpit.

Women may be more aware of this soreness or lymph node changes, especially if a mammogram is done shortly after vaccination.

Tell your mammogram technician when and in which arm you received a COVID-19 vaccine, but don’t delay breast cancer screenings because of your vaccine.

If you have a history of breast cancer and want to avoid a false alarm, choose to receive your COVID-19 vaccine in the arm opposite of the prior breast cancer location.