Why does my heart race after coffee?

Coffee does this because caffeine is a stimulant, and your heart is one of its targets. Caffeine blocks the chemical signals that keep your heart rate settled and nudges adrenaline up - MedlinePlus lists fast heart rate among the effects of too much caffeine, and both the NHS and MedlinePlus name caffeine as a classic cause of palpitations: the pounding, fluttering, or skipped-and-extra-beat feelings in your chest. The NHS is clear that palpitations are common and not usually a sign of anything serious. Sensitivity is personal: some people metabolise caffeine slowly, and an empty stomach, poor sleep, stress, or decongestant medicines amplify the effect. If coffee reliably sets your heart off, the dose is the answer - smaller cups, fewer cups, none after lunch, or switching some to decaf usually settles it within days. MedlinePlus's home advice is exactly that: lower your intake of caffeine, nicotine, or other stimulants, which will often reduce palpitations. Learn the pattern that is never just coffee, because it is short: the NHS says call 911 or go to the ER if palpitations do not go away or come with chest pain, shortness of breath, or feeling faint or fainting. And if cutting caffeine makes no difference, or your heart races with no trigger at all, see a GP - thyroid problems, low potassium, and rhythm conditions can hide behind the coffee story. Pymander is a free AI doctor, 24/7 by text, that can help you weigh it.