Why does drinking black coffee cause palpitations and hand tremors?

Generally, palpitations and hand tremors after drinking black coffee may be caused by physiological factors or pathological conditions such as hypoglycemia or sinus tachycardia. Treatment should be based on the underlying cause. The specific analysis is as follows:

I. Physiological Factors

Black coffee contains a large amount of caffeine, which can promote the central nervous system to secrete catecholamines. Catecholamines can affect β-receptors, leading to increased heart rate and enhanced myocardial contractility, resulting in palpitations.

II. Pathological Factors

1. Hypoglycemia

Substances in black coffee such as caffeine can trigger strong bodily reactions, increasing myocardial contractility and accelerating gastrointestinal motility. This increases the body's demand for glucose. Under these circumstances, the body may become weak due to hunger, easily causing temporary hypoglycemia, which in turn leads to feelings of panic and trembling hands and feet.

2. Sinus Tachycardia

Coffee can stimulate the sympathetic nervous system. Therefore, individuals who drink black coffee on an empty stomach are highly susceptible to developing sinus tachycardia, subsequently experiencing symptoms such as palpitations and hand tremors.

In addition, these symptoms could also be caused by other conditions such as premature beats or paroxysmal atrial fibrillation. If discomfort such as palpitations or hand tremors occurs after drinking black coffee, it is recommended to reduce caffeine intake or switch to low-caffeine or caffeine-free beverages. If symptoms persist or worsen, medical attention should be sought promptly.