<s>[INST] I received a flu shot this morning and i have low blood pressure, 83/63. Could this flu shot account for the low blood pressue. I have a heart problem, also, and i generally have high blood pressure, never do i get low blood pressue,should i call my doctor ? [/INST] Hello! Thank you for asking on Chat Doctor! Your symptoms could be related to heart failure as well as to an allergic reaction from the flu shot. Do you have any other symptoms like tachycardia, itching, shortness of breath, etc.? I recommend going to the ER for a careful physical exam and some tests: - a resting ECG and cardiac ultrasound-some blood lab tests (complete blood count, blood electrolytes)You may need urgent treatment if this situation is caused by an allergic reaction. Hope you will find this answer helpful! Kind regards,  </s>