How long does a reaction to Carbocaine last? My son has had 2 reactions at the dental office, where he thought his heart was going to stop. He lost vision and hearing for 1-2 minutes. He had tremors in his arms. The first time the dentist sent him to another dentist where he had a couple of procedures without reacting. So we went back to the other dentist and he reacted again. The dentist told me that he thought my son was faking it or was just anxious. My son became very anxious when he regained his senses and was upset with the dentist for leaving him alone. He is 19 and has had many dental procedures and never had anxiety before. I believe he had a real reaction.