COVID-19 Vaccine-induced Axillary Lymphadenopathy and Screening Mammogram Findings

Given Ontario’s increasing COVID-19 vaccine uptake and extended accessibility to booster doses, you may be seeing more patients presenting to your practice with swelling in the axillary lymph nodes on the side of vaccination (ipsilateral). This can be worrisome for patients and can also be detected on breast screening mammograms. Here are some suggestions:

  1. For patients that call us concerned about ipsilateral axillary swelling after a vaccine, suggest self-monitoring for up to 6 weeks post-vaccination. If the swelling persists, they will need an in-person assessment and appropriate imaging. For higher risk patients, such as someone with a history of cancer, consider quicker follow-up.
  2. Try to book screening mammograms before or at least 6 weeks after the vaccine.
  3. If ipsilateral lymphadenopathy is detected on a screening mammogram within 0-4 weeks post-vaccination, we should check that the lymph nodes are not palpable within 6 weeks post-vaccination and the radiologist will likely determine the findings are due to the vaccine.
  4. If ipsilateral lymphadenopathy is detected on a screening mammogram more than 4 weeks post-vaccination, the radiologist will likely recall the patient for further assessment.
  5. For more information, please refer to Cancer Care Ontario’s full guidance document for primary care providers on adenopathy related to vaccination.

Here is some suggested messaging to patients for reassurance:

  • If you recently got the COVID-19 vaccine and/or a booster dose or any other vaccine, you may have swelling in the lymph nodes on the side you got the injection (around or in your armpit or neck). This swelling is your body’s normal reaction to the vaccine and is a sign that your body is producing an immune response to the vaccine.
  • If lymph node swelling is seen on your imaging test, the radiologist may ask you to come back for additional imaging to check that the swelling has gone away.
  • If you notice swelling in your lymph nodes after vaccination, and it lasts for more than 6 weeks after your vaccination, you should let your primary care provider know.

Please feel free to email me, Dr. Meghan Davis, your Regional Primary Care Lead ( if you have any questions or concerns.


Dr. Meghan Davis
Regional Primary Care Lead
HNHB Region