This COVID-19 vaccine side effect could be confused for breast cancer, doctor warns

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A reported side effect of the coronavirus vaccine in some women has prompted a warning from doctors, as it could be confused for a common sign of breast cancer. 

Dr. Holly Marshall, a breast radiologist with University Hospitals in Cleveland, told local news station Fox 8 that some of her patients who have received the COVID-19 vaccine have experienced axillary adenopathy, also known as swollen lymph nodes. 

"It’s actually a normal response that the body has to the vaccine," Marshall told the outlet when warning this particular side effect could be mistaken for signs of breast cancer. "It means that the body is making antibodies to fight the COVID-19 infection." 

Many patients who have reported this have found swollen lymph nodes under the arm that they received the jab, she said.

"We also see swollen lymph nodes in patients with breast cancer, so that’s the concern there.  So we are asking everybody who is having a mammogram if they had the COVID-19 vaccine, what dose, when, and what side?" she added. 

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Some trial participants for the Pfizer-BioNTech coronavirus vaccine, for instance, reported side effects including swollen lymph nodes, as well as fever, chills, muscle pain and joint pain, according to the study results, with noted that these side effects were more commonly experienced in those between the ages of 18 and 55. 

Marshall said that many patients are noticing swollen lymph nodes two to four days after receiving the vaccine, with the lymph nodes returning to their normal size two to four weeks later. 

She warned that anyone experiencing swollen lymph nodes for longer than that period of time may require further evaluation by a doctor. 

"This really shows the importance of women getting an annual mammogram screening starting when they are 40-years-old.  Do not delay," the doctor said.