Covid-19 Vaccine Side Effects Can Mimic Breast Cancer Symptoms in Women

  • Date: March 5, 2021

Covid-19 Vaccine Side Effects Can Mimic Breast Cancer Symptoms in Women

Experiencing side effects from the Covid-19 vaccine are signs that your body is building protection against the virus. Common side effects after receiving the Covid-19 are pain and swelling on the arm where the shot was administered. People can also experience fever, chills, tiredness, headaches, or lymph node swelling.

Post-vaccine axillary lymph node swelling (near the armpits) is common as this is a reaction to the injection site of the vaccine. Many women have reported they are concerned that these swollen axillary lymph nodes are breast lumps. This finding has brought women to seek out surgical consultations, mammograms, and ultrasounds. Since these swollen lymph nodes can show up in a mammogram, the Society of Breast Imaging has recommended that women postpone any mammograms scheduled within four weeks after receiving the final Covid-19 shot. If women are experiencing any of the following symptoms related to the breast including pain, skin changes, nipple discharge, or a palpable lump, imaging should not be delayed and they should contact their physician immediately.

Below are more important Covid-19 vaccine side effect trial findings regarding swollen lymph nodes.

  • Axillary lymph node swelling is a side effect found both in men and women in Covid-19 vaccine trials by Pfizer and Moderna.
  • Temporary axillary lymph node swelling occurred in approximately 6% of patients after the first dose, and about 8% after the second dose, according to the Moderna trial.
  • People under the age of 64 developed these axillary lymph nodes twice as often as those who were 65 and older.
  • Most swelling did not require any pain medication or medical assessments and resolved in about 3 days.
  • Axillary lymph node swelling has also been reported as a side effect after people have received the flu, hepatitis, polio, and tetanus vaccines.

Knowing the Signs of Breast Cancer

The fear of breast cancer can be unsettling especially since one in eight women will develop breast cancer in her lifetime. Rest assured, less than 0.5% of patients with breast cancer present with armpit lymph nodes, but when they are present in the setting of cancer, there is a 50% chance they are cancerous, leukemia, or lymphoma.

According to the U.S. Centers for Disease Control and Prevention, some warning signs of breast cancer include:

  • Thickening or swelling of part of the breast.
  • Irritation or dimpling of breast skin.
  • Redness or flaky skin in the nipple area or the breast.
  • Pulling in of the nipple or pain in the nipple area.
  • Nipple discharge other than breast milk, including blood.
  • Any change in size or shape of the breast.
  • Pain in any area of the breast.

If you have signs or symptoms that worry, you should always consult your physician immediately.

For more information regarding side effects of the Covid-19 vaccine, please visit




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