Most airline terms of service say they are not responsible for any loss due to an anaphylaxis on board their aircraft. Further, some airlines require that passengers do not hold the airline responsible for any costs due to an allergic reaction. The conditions of flying with the airline are often agreed to at the time an airline ticket is purchased, regardless of whether the airline later asks that passengers sign an indemnity/waiver. If a passenger’s allergic reaction increases costs to the airline (for example, where the airline has to divert the aircraft), the passenger may have to pay these costs.