14 December, 2020 Allergies are becoming more common; this article, the fourth in a six-part series about the lymphatic system, explores the reasons for this and discusses what happens during allergic responses including anaphylaxis Abstract This article, the fourth in a six-part series on the lymphatic system, discusses the nature of allergy, exploring common allergens and the body’s response to them in atopic people, including anaphylaxis. It questions why allergies are becoming increasingly common, particularly in developed countries, exploring a number of theories. Citation: Knight J, Nigam Y (2021) The lymphatic system 4: allergies, anaphylaxis and anaphylactic shock. Nursing Times [online]; 117: 1, 54-58. Authors: John Knight is associate professor in biomedical science; Yamni Nigam is professor in biomedical science; both at the College of Human and Health Sciences, Swansea University.