she is experiencing swelling; Tenderness in the left armpit and breast area; normal site pain; booster; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 42 year-old female patient received bnt162b2 (BNT162B2), intramuscular, administered in arm left, administration date 29Nov2021 (Lot number: FH8028) at the age of 42 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "Arthritis" (unspecified if ongoing), notes: she got arthritis early. In her mid thirties; "Torn rotator cuff" (unspecified if ongoing), notes: she has a torn rotator cuff. Concomitant medication(s) included: DULOXETINE (ongoing). Vaccination history included: Bnt162b2 (Dose: 1, Lot number: ER8734.), administration date: 02Apr2021, when the patient was 42 years old, for COVID-19 immunization; Bnt162b2 (Dose: 2, Lot number: EN5318), administration date: 23Apr2021, when the patient was 42 years old, for COVID-19 immunization. The following information was reported: IMMUNISATION (non-serious) with onset 29Nov2021, outcome "unknown", described as "booster"; SWELLING (non-serious) with onset 01Dec2021, outcome "unknown", described as "she is experiencing swelling"; BREAST TENDERNESS (non-serious) with onset 01Dec2021, outcome "unknown", described as "Tenderness in the left armpit and breast area"; VACCINATION SITE PAIN (non-serious) with onset 29Nov2021, outcome "unknown", described as "normal site pain". Therapeutic measures were taken as a result of swelling, breast tenderness, vaccination site pain.  Additional information: She is calling about Pfizer BioNTech vaccine. She just got her six month booster. She got Pfizer BioNTech for the first two in the series six months ago. Has Pfizer heard this from anyone else. Her left arm where the breast tissue extends up into the armpit is swollen and tender there. There is a lot of lymphatic drainage in that area. That is what she is experiencing. She is wondering if anyone else has reported that. The site pain began several hours after vaccination. Caller clarified that she is having swelling and tenderness in the armpit and breast area on left side. If it was the other side she wouldn't be calling. Outcome of Event: She just noticed as she was getting in the shower. She looked in the mirror and it is definitely swollen. The first times it was given at Withheld and she had the same nurse both times. Caller thought it was done, but she was not 100 percent positive. She knew they notate it in their system. This time online it asked her preference. She picked the left arm to hurt this time. The first was six months ago, so she was not 100 percent sure which arm it was given in. The nurse this time put it in caller's arm much more gently. The pain in her arm was way less than the first time. This nurse didn't jam it in there and didn't cause trauma. The difference between the first two times is caller didn't ice the arm. This time she iced the arm. She iced it twice the same night as the vaccine. The next day she put a Salonpas patch on it so she wouldn't feel it and so it would go numb. That is the difference for what she did to relieve the discomfort. She has used Salonpas patches multiple times on her neck and shoulder before because. Caller states she doesn't have any allergic issue with Salonpas, so she doesn't think it was that thing. Caller stated she was going to get an appointment incase this was a breast issue. No Emergency Room or Physician Office visit. Caller believed it was an "H". They didn't put the line all the way down for the H and it looks like a plus sign. Expiry: Unknown. two days later, she has tenderness. Her left arm where the breast tissue extends up into the armpit is swollen and tender there. This time she iced the arm. She iced it twice the same night as the vaccine. The next day she put a Salonpas patch on it so she wouldn't feel it and so it would go numb.  No follow-up attempts are possible. No further information is expected.