Mechanism of Vasovagal Syncope During Injection?

Today I encountered a case of needle fainting, so I quickly withdrew the needle and took a rest. Reflecting on my own reactions and those of others when fainting from needles, the main symptoms are nausea, dizziness, sudden sweating, and a feeling of incontinence. Moreover, whether it is traditional Chinese acupuncture or Western medical infusion, the symptoms can occur and are quite similar.

May I ask what the mechanism behind needle fainting is?

  • Personally, I have guessed that it is caused by excessive tension leading to overexcitation of the sympathetic nerves, but I would like to know how traditional Chinese medicine explains it.
  • A friend suggested that qi is diverted elsewhere, causing dysfunction in the overall maintenance of physiological activities, but how would this explain fainting from infusions as well?