Caffeine
Other ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
Caffeine is a well-studied stimulant and ergogenic aid that improves alertness, vigilance, endurance, power, and perceived exertion in many settings. Benefits are dose-dependent but so are anxiety, insomnia, palpitations, and blood pressure effects. Adults generally should keep total caffeine near or below 400 mg/day, and pregnancy guidance is typically lower.
Exploratory record, not a reviewed medical publication.
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This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.
What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
Caffeine is an other most often used for improves alertness and vigilance, improves endurance performance, can improve power and repeated effort. NutriStack rates the overall evidence as strong. A typical adult dose is 1-3 mg/kg for focus or lower-side-effect use; 3-6 mg/kg 30-60 minutes pre-exercise for performance; keep total daily adult intake near or below 400 mg unless clinician-directed, commonly taken as measured caffeine capsule, coffee, or low-sugar beverage with known caffeine content. This profile indexes 3 sources.
- Insomnia
- Anxiety or jitteriness
- Palpitations
- Uncontrolled arrhythmia or significant palpitations without clinician guidance
- Severe anxiety or panic disorder exacerbated by stimulants
The bottom line
Evidence rating strong. Most-documented uses: improves alertness and vigilance, improves endurance performance, can improve power and repeated effort. 3 sources indexed (2001–2021), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Caffeine antagonizes adenosine A1 and A2A receptors, reducing perceived fatigue and increasing arousal. It also increases catecholamine signaling, calcium handling in muscle, and central drive, which can improve endurance and power output. Genetic variation, habitual intake, sleep debt, anxiety sensitivity, and dosing time strongly influence response and adverse effects.1,2
Dosing & protocol.
Absorbs rapidly with peak effects often 30-60 minutes after ingestion. Food may slow onset but can improve tolerability.
What it actually costs.
Real-world pricing across three quality tiers. Assumes Anhydrous caffeine capsule.
Plain caffeine is inexpensive; beverages and gum cost more per effective dose. Updated 2026-06-04.
Full safety detail.
Side effects
- Insomnia
- Anxiety or jitteriness
- Palpitations
- Increased blood pressure
- Reflux or stomach upset
- Headache or withdrawal symptoms
Contraindications
- Uncontrolled arrhythmia or significant palpitations without clinician guidance
- Severe anxiety or panic disorder exacerbated by stimulants
- Uncontrolled hypertension
- Pregnancy should follow obstetric caffeine limits
- Avoid late-day use in insomnia
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Reviews & position papers
3- 1International society of sports nutrition position stand: caffeine and exercise performanceGuest NS et al. · Journal of the International Society of Sports Nutrition · 2021
Caffeine improves endurance, muscular endurance, movement velocity, strength, sprinting, jumping, and sport-specific actions in many settings.
- 2International society of sports nutrition position stand: caffeine and performanceGoldstein ER et al. · Journal of the International Society of Sports Nutrition · 2010
Evidence supports caffeine for endurance and high-intensity exercise with individualized dosing.
- 3Caffeine for the sustainment of mental task performance: formulations for military operationsInstitute of Medicine Committee on Military Nutrition Research · National Academies Press · 2001
Caffeine can maintain vigilance and attention during sleep loss or sustained operations.
Common questions.
Quick answers about Caffeine, drawn from the data on this page.
What is Caffeine?
Caffeine is a well-studied stimulant and ergogenic aid that improves alertness, vigilance, endurance, power, and perceived exertion in many settings. Benefits are dose-dependent but so are anxiety, insomnia, palpitations, and blood pressure effects. Adults generally should keep total caffeine near or below 400 mg/day, and pregnancy guidance is typically lower.
What is Caffeine used for?
Commonly cited benefits of Caffeine include: Improves alertness and vigilance; Improves endurance performance; Can improve power and repeated effort; Reduces perceived exertion; May improve focus during sleep restriction. NutriStack rates the overall evidence as strong.
What is a typical dose of Caffeine?
A typical adult dose of Caffeine is 1-3 mg/kg for focus or lower-side-effect use; 3-6 mg/kg 30-60 minutes pre-exercise for performance; keep total daily adult intake near or below 400 mg unless clinician-directed. The commonly recommended form is Measured caffeine capsule, coffee, or low-sugar beverage with known caffeine content. These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of Caffeine?
Reported side effects include insomnia, anxiety or jitteriness, palpitations, increased blood pressure, reflux or stomach upset, headache or withdrawal symptoms. This is educational information; check with a healthcare professional before use.
How strong is the evidence for Caffeine?
NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
Caffeine in NutriStack.
Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.