Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Caffeine is a stimulant that blocks adenosine receptors in the brain, which keeps the 'tiredness' signal from building up. Besides its everyday use in coffee, tea and soft drinks, it is a medicine: it treats breathing pauses in premature babies (as caffeine citrate) and is added to some headache tablets.
About 95 percent of caffeine is broken down by the liver enzyme CYP1A2. Variants such as rs762551 (CYP1A2*1F) are linked to faster breakdown, especially in smokers, whose CYP1A2 is sped up. Variants in ADORA2A, the gene for one adenosine receptor, have been linked to how anxious or sleepless caffeine makes people. Caffeine is also used as a test substance to measure CYP1A2 activity. There is no CPIC or DPWG guideline.
Every published finding on gene variants and Caffeine. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
CYP1A2 rs762551: Level 3. Metabolism/PK. 4.
ADORA2A rs5751876: Level 3. Toxicity: Anxiety Disorders. 4.
CYP1A2 rs2069514: Level 3. Metabolism/PK. 3.
ADORA2A rs2298383: Level 3. Toxicity. 2.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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