If your next mammogram is set to take place soon after your COVID-19 shot, there’s something you should know: According to the Society of Breast Imaging (SBI), there’s an increased chance of a false alarm on your mammogram.

Swollen lymph nodes can look like cancer

Mammograms are x-rays that help doctors find breast cancer early. That’s when treatment often works best. When checking a mammogram, doctors look for changes in tissue that could be signs of breast cancer. Swollen lymph nodes under an arm can be one such sign.

But swollen lymph nodes can also be a normal reaction to a vaccine, including the COVID-19 vaccines. It’s a natural part of the body’s immune response. The lymph nodes may return to normal size in a few days to a few weeks, according to the American Cancer Society.

But doctors need to be sure that what they’re seeing on a mammogram is not cancer. So women with swollen lymph nodes from a vaccine may get called back in for further tests.

It comes down to timing

If you have both a mammogram and a COVID-19 shot coming up, be sure to ask your doctor for advice. If possible, the SBI suggests that you try to schedule your mammogram before your first COVID-19 vaccine dose or at least four weeks after your second dose. This makes any swollen lymph nodes from the vaccine less likely to appear on your mammogram. But you should not delay care your doctor recommends getting urgently.

In any case, on the day of your appointment, tell the technologist whether you’ve had your COVID-19 shot. Be sure to mention:

• When you got it.
• Which arm you got it in.
• Whether it’s your first or second dose.

This will help your breast imaging team interpret the findings.

Don’t put it off too long

Breast cancer screenings save lives. So even if you choose to delay your mammogram, don’t put it off indefinitely. Visit our Women’s Imaging Center for more information about mammograms.

Reviewed 3/11/2021

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