Doxylamine Succinate Antihistamines To Avoid Allergic Reactions People today have allergic reactions to various things today. Things that they encounter on a daily basis, while they are walking outdoors, eating their meal or what they come in contact with, can all be triggers for an allergic reaction. These allergic reactions can manifest in different ways, trigger different responses. They can range from mild responses to dangerous, lethal ones depending on the severity of the reaction and nature of the person and allergen.