Why do I shiver when I vape?

Shaking hands while smoking e-cigarettes is mostly a normal reaction of the body to substances like nicotine, but sometimes it can also be a warning from the body indicating an "excessive" intake.
The main reason is that the nicotine in e-cigarettes can trigger your body to enter the "fight or flight" mode, causing a series of changes such as accelerated heartbeat and constricted blood vessels, resulting in feelings of alternating cold and heat, and even shivering. Specifically, there are the following aspects:
?? The dual effects of nicotine: As a core stimulant, it triggers the body to release adrenaline within seconds, causing an accelerated heartbeat, elevated blood pressure, and increased respiratory rate. At the same time, nicotine causes intense constriction of blood vessels, especially reducing blood circulation at the extremities, making your hands and feet feel cold, and causing the body to lose heat and experience a sense of coldness and shivering. If consumed in excessive amounts, it will result in obvious physical tremors and a cold sensation.
??️ Minor changes in core body temperature: A study on mice has clearly shown that injecting nicotine causes a dose-dependent decrease in core body temperature, while e-cigarettes cause an increase in oral temperature, and the extremities become colder due to vasoconstriction. This drastic temperature difference of "hot inside but cold hands and feet" can lead to shivering.
?? Other component effects: The propylene glycol (PG) in e-cigarette liquid may cause dryness and a cool sensation in the throat; the cooling agent directly activates the cold receptors in the mouth and throat, resulting in a strong cool feeling; some people may be allergic to PG, which may also cause reactions such as shivering.
?? Health condition and psychological factors: If the e-cigarette contains cannabinoids, certain components may also cause a decrease in body temperature; after a long period of not smoking and then re-introducing nicotine, withdrawal reactions such as shivering and sweating may occur; nicotine may also affect insulin release, leading to hypoglycemia, one of the symptoms of which is hand tremors; psychological factors such as anxiety may also superimpose with the effect of nicotine, intensifying the feeling of tremors.
Additionally, if the e-liquid contains prohibited ingredients (such as etomidate), it can also cause severe tremors, but this is an illegal act; if tremors are accompanied by fever and breathing difficulties, it might indicate that the body has had a severe reaction to the e-cigarette.
?? Summary
Shaking hands while vaping is usually just a temporary physiological reaction. It is recommended that you try reducing the nicotine concentration, switching to high VG (Vegetable Glycerin) e-liquid, and avoiding cool flavoring agents to reduce the irritation. However, if the shaking is very severe, or accompanied by other discomfort such as nausea, headache, or rapid heartbeat, please stop immediately and consult a doctor.