Form Comparison

Caffeine Anhydrous vs Caffeine Citrate

How caffeine anhydrous and caffeine citrate differ in potency, absorption, tolerance, and cost.

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Quick verdict. Once dissolved, they are the same caffeine; the difference is labeling. Caffeine citrate is half caffeine by weight, so 200 mg of citrate is 100 mg of caffeine, and its real use is prescription treatment of apnea in premature infants. For alertness or exercise, choose anhydrous, dosed in milligrams of caffeine and never scooped as bulk powder.

Side by Side

Caffeine Anhydrous Caffeine Citrate
Active content 100% caffeine 50% caffeine
Absorption High High
How it is absorbed Essentially complete oral absorption, peak plasma levels in 30-120 minutes. Cleared mainly by hepatic CYP1A2 with a half-life of about 5 hours that varies widely. Dissociates in solution to caffeine and citric acid; pharmacokinetics are those of caffeine.
Typical dose 100-200 mg per dose; ergogenic dosing 3-6 mg/kg Prescription neonatal dosing; 2 mg caffeine citrate equals 1 mg caffeine
Common uses alertness, exercise performance, pre-workout formulas apnea of prematurity (prescription)
Side effects Jitteriness, tachycardia, insomnia, GI upset. As for caffeine.
Cost Low Moderate
Also called anhydrous caffeine, pure caffeine citrated caffeine
Labels in index 82 0

When to Choose Caffeine Anhydrous

Choose caffeine anhydrous when you want a precise, inexpensive dose. Dehydrated caffeine, the same molecule as in coffee. Bulk pure powder is dangerous: FDA notes a single teaspoon can contain about 3,200 mg.

Caffeine Anhydrous

Plain caffeine in a tablet. Precise dosing is its only advantage over coffee, and before competition that advantage is real.

What to look for: 100-200 mg tablets. Dose by body weight; 3 mg/kg is a reasonable starting point for exercise.

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When to Choose Caffeine Citrate

Choose caffeine citrate when a neonatal or prescription protocol calls for it. Labels may state compound weight, which is double the caffeine content.

Caffeine Citrate

Choose caffeine citrate when a neonatal or prescription protocol calls for it.

What to look for: Caffeine Citrate named on the Supplement Facts panel, with the amount per serving stated.

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Products on Titrate

In Titrate's index of NIH label data, 82 labels named as caffeine products list caffeine anhydrous and 0 list caffeine citrate.

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Caffeine does not have its own search category yet. Each product above links to its full label in the NIH database.

Related

References

US Food and Drug Administration. Spilling the Beans: How Much Caffeine is Too Much?.

Juliano LM, Griffiths RR. A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology (Berl). 2004;176(1):1-29.

Cornelis MC, et al. Coffee, CYP1A2 genotype, and risk of myocardial infarction. JAMA. 2006;295(10):1135-1141.

Drake C, et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013;9(11):1195-1200.

Nehlig A. Interindividual Differences in Caffeine Metabolism and Factors Driving Caffeine Consumption. Pharmacol Rev. 2018;70(2):384-411.

Guest N, et al. Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes. Med Sci Sports Exerc. 2018;50(8):1570-1578.

Guest NS, et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18(1):1.