200 mg per tablet, across the major brands
The standard over-the-counter caffeine tablet carries 200 mg. That is the strength on the generic label cited here, and NoDoz Maximum Strength and Vivarin carry 200 mg per caplet or tablet too, according to their drug labels. One tablet is about two 8 oz cups of drip coffee at USDA’s reference strength (95 mg each), or two and a half standard cans of Red Bull.
The labels agree on the directions: adults and children 12 and over take one tablet no more often than every 3 to 4 hours, and NoDoz’s label allows half a caplet. They also say not to use caffeine tablets in children under 12 or as a substitute for sleep, and to limit other caffeine-containing medicines, foods and drinks while taking them, because too much caffeine may cause nervousness, irritability, sleeplessness and occasionally a rapid heartbeat.
Why a tablet is different from a coffee
A cup of coffee paces itself: it takes time to drink, and the volume is a cue. A tablet delivers 200 mg in one swallow. Two tablets are 400 mg, the whole daily figure the FDA cites for healthy adults, and a third passes it. One tablet also sits exactly at the 200 mg that EFSA assessed as a safe single dose for healthy adults, so taking two together goes beyond it.
The FDA’s warning about concentrated caffeine shows why the format deserves care. It estimates that toxic effects, such as seizures, can be seen with rapid consumption of around 1,200 mg of caffeine: the amount in six of these tablets. Pure and highly concentrated caffeine powders are the extreme case, since 1,200 mg is less than half a teaspoon of pure caffeine.
If you take one
Count it with everything else. A tablet, a morning cup of drip coffee and an afternoon can of Celsius come to 495 mg. The labels advise asking a health professional before use if you are pregnant or breastfeeding, and to get medical help or contact a Poison Control Center right away in case of overdose.