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.
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.
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.
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.
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.
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.
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.
A new lump in the breast or underarmThickening or swelling in the breastBreast skin irritation or dimplingNipple pain or pullingRedness or flakiness in the nipple area or breastNipple discharge (other than expected breast milk), this includes bloodChanges in breast size or shapeBreast pain
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.
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:
FeverHeadacheFatiguePain 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.
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.
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.
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.
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.
