What You Need to Know

Some women who receive the COVID-19 vaccine develop swollen lymph nodes under their arm on the same side as their vaccine injection. This is the normal immune reaction to a vaccine. These swollen lymph nodes usually return to normal on their own in a few days or weeks (1).

Why do swollen lymph nodes matter?

Breast radiologists look closely for any changes on your mammogram. Swollen lymph nodes under one arm can be seen on a mammogram and can be a rare sign of breast cancer.

What happens if there are swollen lymph nodes on my mammogram?

Depending on your medical history and when you received your vaccine, the breast radiologist may recommend that you return to the breast center for an ultrasound of your underarm area and they also may recommend a follow up exam to show that the lymph nodes have returned to normal size.

When should I schedule my screening mammogram?

Try to schedule your screening mammogram before your first COVID-19 vaccine dose or at least 4 weeks after your second vaccine dose. This reduces the chance that swollen lymph nodes from the vaccine will appear on your mammogram.

What if my mammogram is already scheduled?

Keep your vaccination appointment. Getting vaccinated is critical to stop the spread of COVID-19. Consider rescheduling your screening mammogram if possible before your vaccine. However, if you are already overdue for your screening exam or cannot reschedule within the next few months, keep your screening mammogram appointment and keep your COVID-19 vaccination appointments. Regular screening mammograms ensure that breast cancer can be detected as early as possible. Both are very important to ensure that you stay healthy. It’s especially important to keep your mammogram appointment if you are significantly overdue for screening. Remember: annual screening saves the most lives.

What should I tell the technologist on the day of my screening mammogram?

Notify your mammography technologist if you have received a COVID-19 vaccine. Tell her when you received the vaccine, and which arm the vaccine was given. State whether it’s your first or second dose. This information will help the breast radiologist interpreting your screening mammogram.

What if I have other breast problems?

If you have any changes in your breast or underarm, such as pain or a lump, contact your medical provider. The guidelines above are only for women with no breast symptoms who are scheduled for a COVID-19 vaccine.

(1) SBI Screening Mammography Recommendations for Women Receiving the COVID-19 Vaccine, Society of Breast Imaging, 2021