Is a higher dose always better?

No. Dose-fit rewards landing inside the range studied for the outcome — over-dosing (common with melatonin) or under-dosing both lower the score. The goal is the effective dose, not the biggest number.

What does the Value score mean?

The Value score compares a product's price per serving with clinically relevant products ranked for the same outcome. A score of 50 is the typical price; above 50 means better value than typical, while below 50 means the product costs more than typical. It is a 0–100 value signal, not a percentile.

Why is the cheapest product not #1?

Cost is only one input. The cheapest pick here is a citrate form with weaker absorption and a stock-risk flag, so it leads on Value-for-cost but trails on the composite that also weighs evidence, dose fit and availability.

Are these affiliate links?

Retailer links may be affiliate links and DoseRank may earn a commission. Rankings and placement are determined by the scoring model only — never by payment from a brand.

Is this medical advice?

No. DoseRank summarizes evidence to help you choose; it is not a substitute for a clinician, especially if you are pregnant, breastfeeding, on medication, or managing a health condition.

Improve reaction time

What this outcome means

Reaction time is how quickly you register a signal and respond, whether that's hitting the brakes or answering a prompt on screen. On DoseRank it maps to a defined health outcome built from human studies on simple and choice reaction-time tasks, response latency in milliseconds, and lapse frequency – data sourced from open sources and specialized resources. DoseRank is not medical advice.

Who it's for

Split-second sportsAthletes whose performance hinges on fast, reliable responses.

Behind the wheelDrivers and operators who need quick reactions to stay safe.

Slowing with ageOlder adults noticing a lag in how fast they respond.

Stack buildersAlready taking supplements such as Caffeine Anhydrous and want the dose right.

Evidence level

92Strong

Caffeine Anhydrous – has strong public evidence. DoseRank looks at both evidence quality and formula fit. A DoseFit Score of 71 means this product's ingredient forms and doses are close to what was used in the studies behind this ranking - DoseRank weights each product ingredient.

Best ingredients

Caffeine Anhydrous is the best supported ingredient signal for this outcome.

Dose partly matchedDoseFit 71

Scores reward products dosed inside or above the studied range, not just the right ingredient. Examples: In range: Caffeine Anhydrous 100 mg vs 50-300 mg.

Processed

968

Available

968

Ingredients

Brands

181

Coverage

100%

How to read the scores

What every metric means

Each score is 0–100. Higher is better for every metric below.

CompositeThe overall DoseRank score — a weighted blend of clinical strength, evidence, dose fit, trust and value.Higher is better

ClinicalHow strongly the formula's ingredients and doses match what clinical studies used for this outcome.Higher is better

EvidenceHow much published human research backs the formula's key ingredients for this outcome — both how many studies exist and how strong they are.Higher is better

ValueHow the price per serving compares with similar products for this outcome — 50 is the typical price, higher means better value for your money.Higher is better

TrustHow well customers rate this product, with extra weight given to ratings backed by a large number of reviews.Higher is better

PopularityHow strongly this product sells compared with the other ranked products for this outcome.Higher is better

This legend covers the scores on this page — for data sources, scoring weights, and limits, read the full methodology →

Not sure which is right for you?

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Take 60-sec quiz

Get a personal report

A saved, shareable breakdown: your matched products, dose math, interaction flags to discuss with a clinician, and a price-tracked stack you can revisit.

Questions

Frequently asked

Each product gets a composite score blending clinical strength, evidence, dose fit, trust and value. The #1 on the DoseRank tab has the highest composite; the other tabs re-rank the same products by Value, Trust, or Popularity. Placement is never paid.

Improve reaction time

What this outcome means

Who it's for

Split-second sportsAthletes whose performance hinges on fast, reliable responses.

Behind the wheelDrivers and operators who need quick reactions to stay safe.

Slowing with ageOlder adults noticing a lag in how fast they respond.

Stack buildersAlready taking supplements such as Caffeine Anhydrous and want the dose right.

Evidence level

92Strong

Best ingredients

Caffeine Anhydrous is the best supported ingredient signal for this outcome.

Dose partly matchedDoseFit 71

Scores reward products dosed inside or above the studied range, not just the right ingredient. Examples: In range: Caffeine Anhydrous 100 mg vs 50-300 mg.

Processed

968

Available

968

Ingredients

Brands

181

Coverage

100%

Relevant ingredients

Which ingredient types matter for reaction timeOpen to see which ingredient types matter for reaction time

229 products across 1 ingredient types — open to filter the ranking.

Use types to filter ranked products

Alkaloids & Stimulants

229 products

Plant-derived nitrogen compounds like caffeine that stimulate the nervous system. Effective but dose-sensitive, with real tolerance and dependence risk.

Typical:

Top decision cards

Best products for reaction time

Ranking by · Composite outcome score

Best overall — the composite outcome score.

Top pick · DoseRank

Why this ranks #1 for reaction time

Force Factor, ProbioSlim®, Weight Loss Essentials, 120 Vegetable Capsules

Force Factor$0.15 / serving4.5 · 10,331Available now

Also helps with

Alertness

Fatigue

Vitamin C status

Why this ranks here

Evidence fitCaffeine Anhydrous is the strongest evidence signal for this outcome.
Dose fitCaffeine Anhydrous at 100 mg lands inside the studied 50-300 mg window.
Price / serving$0.15 per serving — low price tier for this outcome.
AvailabilityIn stock across major retailers; 99% availability confidence.
TrustStrong trust signals — consistently high marks from verified buyer ratings.

The numbers

100 mgIn rangeinside the studied 50-300 mg window

100 mg

10 mcg

25 mg

10 mg

60 mg

2 mg

Compare top 3 Product data Open at retailer

The rest of the ranking · DoseRank

Top 10 ranked products

Nutricost, Caffeine with L-Theanine, 240 Capsules

NutricostClinical89Dose fit71Popularity89$0.05/ serving

California Gold Nutrition, TheanineUP®, L-Theanine & Caffeine Plus Cocoa and Matcha, 60 Veggie Capsules

California Gold NutritionClinical89Dose fit71Popularity91$0.19/ serving

Applied Nutrition, Green Tea Fat Burner®, 90 Fast-Acting Liquid Soft-Gels

Applied NutritionClinical89Dose fit77Popularity84$0.36/ serving

EcoTeas, Loose Yerba Mate, Green Energy, Unsmoked, 16 oz (454 g)

EcoTeasClinical89Dose fit68Popularity76$0.18/ serving

Nutricost, Guarana Powder, 3.5 oz (100 g)

NutricostClinical89Dose fit83Popularity68$0.14/ serving

Nutrex Research, LIPO-6 Black, Ultra Concentrate, 60 Liqui-Caps

Nutrex ResearchClinical89Dose fit67Popularity80$0.37/ serving

Sports Research, L-Theanine & Caffeine, 2-in-1 Formula, 60 Softgels

Sports ResearchClinical89Dose fit71Popularity84$0.34/ serving

MuscleTech, Hardcore® Elite, 110 Rapid-Release Thermo Caps

MuscleTechClinical89Dose fit85Popularity80$0.49/ serving

Hydroxycut, Weight Loss Original, 72 Rapid-Release Capsules

HydroxycutClinical89Dose fit81Popularity80$0.58/ serving