It's important to note that antihistamines don't typically prevent you from undergoing surgery. These medications are usually well-tolerated and don't interfere with the anesthetic drugs used during surgical procedures. However, some antihistamines can cause dry mouth and drowsiness, which may affect your comfort level and recovery time after surgery. It's crucial to have a clear and open discussion with your surgeon and the anesthesiology team about all medications, including over-the-counter drugs and supplements, that you're taking prior to the surgery. They will give you specific instructions on which medications you should stop taking before surgery, as well as when to stop taking them. To give you a more personalized answer, we would need to know which specific antihistamine you're taking, the reason you're taking it, the dosage, and how frequently you're taking it. Remember, your safety is the top priority when considering any surgical procedure. Please don't hesitate to ask your healthcare team any questions you might have regarding this matter. Sincerely, Dr. Katzen