Why it's called 蕁麻疹?

Question

I tried to find out why hives in Mandarin is called 蕁麻疹 to no avail. 蕁麻 in English is urtica, a genus of flowering plants in the family Urticaceae. Please help! Thank you ~

Answer 1

Texts below are excerpted from the linked article:

蕁麻疹（hives、urticaria）是一種很常見的皮膚病，俗稱風團或風疹塊[4]，有的地區叫鬼風疙瘩，中醫稱癮疹[5]，客語稱冷瘼，是一種皮膚過敏。症狀是局部皮膚忽然成塊地紅腫，發癢或刺癢[1]。.....

..... 蕁麻疹在兩千多年前的中醫典籍—「內經」一書中即有相關的記載[7]，因症狀來的快去得快疾如風故又俗稱風疹塊，後世用發作的感覺類比""接觸蕁麻""而得名[8]...蕁麻疹的英文「urticaria」源自拉丁文，urtica原意為「蕁麻」[9]。

8. 《本草綱目．卷十七下》「蕁麻生汗寧府山野中…觸人如蜂蠆螫。

Note: I think the word 蕁麻 was not derived from translation, nor a borrowed word, but a name of the plant named by the Chinese. For example, if the symptom is similar to the reaction from getting in touch with another plant, say 蘭花(Orchid), then the name of the disease would have been called "蘭花疹":)

Answer 2

Hives are a type of rash caused by an immune system response. 疹 means a skin rash.

蕁麻 is a type of plant with stinging hairs on its leaves. These hairs cause hives when you touch the plant. In English these plants are called "stinging nettles". In Spanish, "ortiga".

So literally "hives" are "nettle rash". This makes sense because a common cause of hives is a sting from a nettle plant.