Got Covid vaccine; He is on blood thinner (Unspecified Medication); Bruise on his opposite arm, he got the shot in the left arm and he saw the bruising on the right elbow/Bruise is getting bigger and bigger/Bruise started to expand on his whole arm, more towards forearm and it started to look like all black and blue; This is a spontaneous report from a contactable other health care professional (Nurse practitioner reporting about her husband). A 75 years old male patient of an unspecified age received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, Formulation: Solution for injection, Lot Number: EL9263), via an unspecified route of administration, administered in Arm Left on 04Feb2021 as dose 2, single (age at vaccination 74 year old) for covid-19 immunisation. Medical history included hypertension, Peripheral arterial occlusive disease, atrial fibrillation, Prediabetic, chronic obstructive pulmonary disease, coronary artery disease. Concomitant medications included ATORVASTATIN, BUPROPION; acetylsalicylic acid (BABY ASPIRIN); CILOSTAZOL; tamsulosin hydrochloride (FLOMAX [TAMSULOSIN HYDROCHLORIDE]), METFORMIN, METOPROLOL; piroxicam (PAXIL [PIROXICAM]); rivaroxaban (XARELTO). Historical vaccine included bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, Formulation: Solution for injection, Lot Number: not reported), via an unspecified route of administration on 14Jan2021 as dose 1, single (age at vaccination 74 year old) for covid-19 immunisation. Reporter (Nurse practitioner) stated that, her husband got Covid vaccine, second dose on 04Feb2021, just three days ago and he was on blood thinner (Unspecified Medication). So, everybody, every time, he went to get the Covid vaccine, they ask if he is on blood thinner (Unspecified Medication). He did well with the first dose and second dose also. But yesterday on 07Feb2021, last evening, he saw a bruise on his opposite arm, he got the shot in the left arm and he saw the bruising on the right elbow. But he didn't pay much attention to it because he is on blood (sentence incomplete), sometimes he like you know get bruised of (further clarification unknown). This morning, in this afternoon, this was the first time happening to him, this afternoon, that bruise started to expand on his whole arm, more towards the forearm and it started to look like all black and blue. So, reporter called a doctor and had appointment to see the doctor tomorrow morning. He had no other symptoms. Reporter took the pen and draw a line around it to see if it expands further and it has again expanded a lot, since afternoon to this evening. So, his concern was, is it somehow related to this vaccine, it has never happened to him. The bruise was getting bigger and bigger. The clinical outcome for event Got Covid vaccine; He is on blood thinner (Unspecified Medication) was unknown while rest of events outcome was not recovered. Causality: Reporter stated, "I don't know that is why I am calling you because my concern is that, although he is on blood thinner (Unspecified Medication) but he haven't had episode like this. So, I will say may be." (hence, causality tab left unchecked as report was not sure)  Follow-up (11May2021): Follow-up attempts completed. No further information expected.