My husband had a routine single needle injection to withdraw blood for routine blood sample last Saturday late morning. He experienced some swelling at the point of injection in crook of right elbow.  I had the same with no side effects. 5 days later he has extensive bruising and some discomfort. We live in Hong Kong and have previously had no problem with getting routine blood tests. What could have caused this reaction?
Dear Friend. Welcome to Chat Doctor. Hi, I am Chat Doctor, I have read your query in detail, I understand your concern. This is probably thrombophlebitis. If you could send me the photograph, I could give you a better idea. Thrombophlebitis improves itself. Usually no treatment is required. However, if severe, Tomophobe ointment for local application can be used. This is my personal opinion based on details available here.  If you still have any other query, you may please ask me. Stay Healthy. Chat Doctor, MD