Reasons Behind Breast Pain After the COVID-19 Vaccine

Women have reported breast pain as a side effect of the vaccine

Vaccines can cause side effects such as headaches, fever, or joint pain. The most common side effect of the COVID-19 vaccine is injection site soreness. 

There are also reports of axillary (armpit) pain near the breast on the side of the COVID-19 vaccination. Mammograms (breast cancer screening) have also detected swollen lymph nodes after the injection. While this may sound alarming, these are known side effects of the COVID-19 vaccine, and they resolve on their own.

This article covers breast pain as a side effect of the COVID-19 vaccine, its impact on mammogram results, non-vaccine causes for breast pain, and how to find relief.

Cropped woman wearing a mask and holding her chest, as if in pain.

Panuwat Dangsungnoen / Getty Images

Breast Pain: A Side Effect After COVID-19 Vaccine

Breast pain is a possible side effect of several vaccines, including influenza (flu) or the human papillomavirus (HPV). But it appears more frequently as a side effect of the COVID-19 vaccine. 

Moderna and Pfizer Clinical Trial Reports

Moderna and Pfizer reported lymph node swelling and underarm tenderness as side effects during their clinical trials for the novel COVID-19 mRNA vaccination. 

Around 11% of people who received the Moderna vaccine had lymph node swelling and tenderness after the first shot and 16% after the second. Pfizer trials showed 0.3% of their trial participants reported these side effects. 

Vaccines trigger a normal response in the immune system, which can cause side effects such as swelling, joint pain, or a mild fever. This response is usually the cause of breast pain after the COVID-19 vaccine.  

Underarm tenderness and swollen lymph nodes in the armpit area may occur with breast pain. Similar to injection site soreness, these side effects are usually on the same side where the shot was given. They can appear as early as one day after the vaccine.

What Are Lymph Nodes?

Lymph nodes are part of the lymphatic system within the immune system. They are small, bean-sized organs that trap pathogens (things that make you sick such as bacteria and viruses). This prevents the pathogens from circulating throughout the body. Swollen lymph nodes are often a part of the immune response. 

How Long It Lasts 

Breast pain typically resolves within two days of getting the Moderna vaccine and 10 days of getting the Pfizer vaccine. These are average times, and there are reports of these side effects lasting more than six weeks.  

Other Possible Breast Changes 

When breast pain is a side effect of the COVID-19 vaccine, there is no cause for alarm. It does not indicate any health problems and will resolve on its own. If it doesn’t resolve within a few days of the vaccine, notify your healthcare provider. 

Breast pain can also be a breast cancer symptom, making this side effect alarming for many people. However, breast pain as a symptom of breast cancer is rare. Studies report a 1% to 7% chance of cancer being the cause of breast pain. 

Breast Changes That May Occur With Breast Cancer

Often, breast cancer is a silent disease, meaning there are no symptoms. When there are symptoms, they may include the following breast changes:

  • A new lump in the breast or underarm
  • Thickening or swelling in the breast
  • Breast skin irritation or dimpling
  • Nipple pain or pulling
  • Redness or flakiness in the nipple area or breast
  • Nipple discharge (other than expected breast milk), this includes blood
  • Changes in breast size or shape
  • Breast pain

Effects on Mammogram Results

Lymph node swelling in the armpit is a normal reaction to the COVID-19 vaccine. However, it causes suspicion when it’s a mammogram finding, as it can be mistaken for a sign of breast cancer. 

When COVID-19 vaccine side effects cause these mammogram findings, it can lead to unnecessary worry and testing. Ideally, it’s best to get a mammogram before the vaccine. But, if you do have a mammogram shortly after the COVID-19 vaccine, notify the mammogram technician.  

If you have suspected breast cancer or are getting breast cancer treatment, it’s best to receive the vaccine on the arm opposite of the possible or confirmed breast cancer.

While breast pain typically resolves within the average times mentioned above, lymph node swelling could still appear on a mammogram for up to 43 weeks. One study showed that: 

  • On average, 44% of those who receive the COVID-19 vaccine have ​​lymph node swelling.
  • 46% of those who receive the Moderna vaccine have ​​lymph node swelling.
  • 38% of those who receive the Pfizer vaccine have ​​lymph node swelling.
  • 39% of those who receive the Johnson & Johnson vaccine have ​​lymph node swelling.

These studies note much higher percentages than the clinical trials. This is likely because the trial participants self-reported lymph node swelling during clinical trials, but the study used mammogram findings instead. This indicates that swollen lymph nodes could appear on a mammogram for quite some time after the symptoms you feel resolve.

Should I Postpone a Mammogram After a COVID-19 Vaccine?

Initially, there was a recommendation to wait six to eight weeks after the vaccine to get a mammogram. But professional organizations, such as the Radiological Society of North America, no longer recommend delaying mammogram screenings after the COVID-19 vaccination. 

Where the CDC Stands  

The Centers for Disease Control and Prevention (CDC) states that the COVID-19 vaccine side effects are generally mild and go away within a few days. They list the most common side effects as follows:

  • Fever
  • Headache
  • Fatigue
  • Pain at the injection (shot) site

Breast pain and lymph node swelling are not listed as common side effects, but the CDC notes that they occur. 

Ongoing COVID-19 Research Efforts

Because COVID-19 is still a new disease, research efforts are constant and continual. The National Library of Medicine offers a list of completed and ongoing World Health Organization (WHO) COVID-19 studies. This information stays current, as they update it weekly.

Non-COVID Causes of Breast Pain 

Non-vaccine-related breast pain is a common complaint and affects up to 70% to 80% of women. 

Cyclic breast pain typically affects both breasts and may cause underarm soreness. Hormones are the culprit for this type of breast pain. It’s a tender or heavy feeling that comes and goes based on your menstrual cycle (period). 

Noncyclic breast pain is not related to your menstrual cycle. It does not come and go and may cause sharp or burning pain. This pain occurs on one side and typically stays in the same place.

Noncyclic breast pain can be caused by the following:

  • Large breasts
  • Poor-fitting bra
  • Mastitis (breast inflammation that is sometimes infected)
  • Pregnancy
  • Breastfeeding
  • Injury
  • Radiating pain
  • Fibrosis
  • Gynecomastia (breast growth in people assigned male at birth)

Relief for Post-Vaccine Breast Pain

Relief for post-vaccine breast pain is similar to relieving injection site swelling and tenderness. You can try the following techniques:

  • Cool pack: Place a cool, wet washcloth on the breast or underarm.
  • Arnica: This natural remedy helps with swelling and inflammation. It comes in pellets you place under the tongue and cream you can rub on the skin.
  • Topical pain medications: Topical pain medications are patches and creams you place on the skin to help relieve soreness in one area.
  • Tylenol (acetaminophen) or Advil or Motrin (ibuprofen): If the above remedies don’t work, you can try these over-the-counter (OTC) pain medications. 

OTC Medications and the COVID-19 Vaccine

According to the CDC, little is known about the effects of taking OTC pain medicines such as Tylenol or Advil before the vaccine. They don’t yet know if they affect how the vaccine works. 

The CDC recommends continuing your OTC medications if you currently take them. If you don’t regularly take OTC pain relievers, it’s best to wait until you get your vaccine rather than take them for prevention.

Summary 

Vaccines can cause side effects such as a mild fever or headache. The most common symptom of the COVID-19 vaccination is soreness at the injection (shot) site.

While breast pain is not the most common vaccine side effect, it can occur with some vaccines. It seems to be more common in the COVID-19 vaccine than in others.

The COVID-19 vaccine can also cause lymph node swelling under the arm. This can create a false positive on a mammogram (breast cancer screening), which can cause stress and unnecessary testing. 

Breast pain is a common complaint among those assigned female at birth. It can result from hormones, poorly fitting bras, large breasts, and more. 

A Word From Verywell 

If a mammogram and COVID-19 vaccine are in your near future, it may be best to wait to get the vaccine until a day or two after the mammogram. If you’ve already had the shot, let the mammogram technician know before the procedure. 

Regardless, don’t delay your mammogram. Breast cancer screenings are life-saving. They lead to early detection, diagnosis, and treatment which typically means a better outcome.

Frequently Asked Questions

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Brandi Jones, MSN-ED RN-BC
Brandi is a nurse and the owner of Brandi Jones LLC. She specializes in health and wellness writing including blogs, articles, and education.