Caffeine

Caffeine anhydrous

Snapshot

Indications	Contraindications
Exercise performance¹ Attention and vigilance² Performance after sleep loss^{1, 3, 4} Apnea of prematurity⁵	Panic disorder⁶ Caffeine hypersensitivity⁷

Caffeine is a trimethylxanthine found in coffee and other beverages that stimulates alertness mainly by blocking adenosine receptors. That effect drives its use for attention and vigilance, including in pilots, where a single 300 mg dose lessened the decline in night-time performance after extended wakefulness⁸. In preterm infants, caffeine citrate is used for apnea of prematurity.

A sports nutrition position stand reports benefits for endurance and attention, and a meta-analysis found gains in attention, accuracy, and speed during exercise. In preterm infants, a meta-analysis found less apnea with caffeine, while a 2025 randomized trial of extended therapy in moderately preterm infants found no shorter hospitalization. In 2025, an observational and Mendelian randomization study in a large biobank cohort linked higher coffee intake to lower atrial fibrillation risk, and no randomized trial has confirmed it. Roughly 14,000 products list caffeine, mostly capsules, powders, and tablets, often paired with L-theanine; see Form comparison.

Patients with panic disorder are far more prone to caffeine-induced panic attacks than healthy adults⁶. Health Canada labels ask for a practitioner's advice before use with lithium⁷, and LiverTox notes that advanced cirrhosis slows caffeine clearance⁹.

Last updated October 15, 2026. Read how we make monographs.

In the full monograph

74 sources, 63 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources