Why does coffee cause heart palpitations?

Coffee can cause heart palpitations mainly because of caffeine, a stimulant that has several effects on your body.

Caffeine stimulates the nervous system. Caffeine blocks the action of adenosine, a substance that helps your body relax. This activates the sympathetic nervous system, the fight-or-flight system. Your heart beats faster and more forcefully.

Caffeine can increase the release of adrenaline and noradrenaline. These hormones speed up your heart rate and can cause an irregular feeling. Caffeine also temporarily constricts blood vessels and raises blood pressure. This can contribute to the feeling of palpitations, especially in people who are sensitive to caffeine.

Not everyone reacts the same way. You may be more likely to experience palpitations if you are not used to drinking much caffeine, if you are stressed, anxious, or sleep deprived, if you drink coffee on an empty stomach, if you metabolize caffeine faster due to genetic factors, or if you drink too much or highly concentrated coffee (espresso, energy drinks).

In some people with underlying arrhythmias (such as atrial fibrillation or SVT), caffeine can trigger symptoms — although this is not the case for everyone.

Source: https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2782015

Author: Prof. Dr. Dirk Devroey - Latest update: 2025-12-02 - Copyright: Clinifacts 2026