HOME › FORMULAS › INGREDIENTS › CAFFEINE
Caffeine
A stimulant, and one of the best-studied ingredients we work with. It sits in three BOOST formulas, all served early in the day, with one claim on our register that only holds from 75 mg a serving. Coffee, tea, mate and guarana bring it too, so the engine counts your caffeine as one total, not formula by formula.
WHAT WE ARE ALLOWED TO SAY
One claim, and it starts at 75 mg.
This is the wording on our claims register for caffeine, recorded as authorised on the condition of 75 mg of caffeine per serving. We quote it exactly, and only where the dose clears that line: all three of our formulas do on a full pour, at 100, 75 and 150 mg. One of our own research notes could not find the claim on the EU register, so its status is being checked, and we would rather tell you that than keep quiet about it.This is the wording on our claims register for caffeine, recorded as authorised from 75 mg per serving. One of our own research notes could not find it on the EU register, so its status is being checked.
Caffeine has no claim on our register for energy, for endurance or for sport. Our ingredient file mentions two endurance wordings, at 3 mg per kilo of body weight an hour before exercise, but they are not on our claims register, so we do not use them. In Acute energy, the claim about tiredness and fatigue comes from the vitamin C next to it; in Pre-workout, the performance claim comes from the creatine.
WHY ANHYDROUS
The molecule is the same. The count is not.
Caffeine from a lab, a coffee bean, tea, mate or guarana is the same molecule, so the form is not a claim argument and we do not use it as one. The form on file is anhydrous caffeine, 99% pure or more: it dissolves in water, stays stable in liquid and is almost completely absorbed, which is what a formula served in 0.2 ml pulses needs. It also lets us declare exact milligrams, where for plant sources our files can only give the caffeine as a range.
Caffeine at 99% purity or more, the preferred form in our file. It is taken up almost completely by mouth, with a peak in the blood 30–45 minutes later.
Guaranine and mateine are listed in our file as synonyms of caffeine. Our notes accept caffeine from green tea or guarana only where a formula has to be described as natural, and it counts towards the same total either way.
It dissolves in water, 21.7 g per litre at 25 °C, and stays stable in liquid. As a raw material it is sensitive to moisture, and it tastes bitter.
Our files do not agree on purity: the form record says 99% or more, an internal note says a 90% minimum, and our formula records do not yet name the form that goes into each batch. Nothing in our files says one source of caffeine works better than another, and we are not going to imply it. What they do agree on is timing: it starts to act within 15–45 minutes, and its half-life is 3–5 hours in healthy adults, 1.5 to 3.5 times longer in pregnancy, on oral contraceptives or with liver disease.Our files do not agree on purity, 99% or 90%, and our formula records do not yet name the form in each batch. They agree on timing: it acts within 15–45 minutes and has a half-life of 3–5 hours.
WHERE IT APPEARS
Three of the twenty-nine carry caffeine.
All three are BOOST formulas, and all three are served before the afternoon runs out: never after 2 pm for Cognitive & focus and Acute energy, never after 16:00 for Pre-workout. Our ingredient file is stricter and says no caffeine after 2 pm at all, because with a half-life of around 5 hours it can still cost you sleep 6 hours later. The two sources disagree on Pre-workout, and that is written down for a clinical decision rather than smoothed over.
THE CEILING
400 mg a day, from everything you take.
EFSA puts the safe total for a healthy adult at 400 mg a day, with no more than 200 mg in a single dose, and at 200 mg a day in pregnancy and breastfeeding. The limit covers all your caffeine, coffee and tea included, not our formulas on their own. Our three formulas add up to 325 mg, which is why the engine treats caffeine as one budget: from 200 mg a day it warns you, and from 400 mg it blocks the plan.EFSA puts the safe total at 400 mg a day for a healthy adult, 200 mg in a single dose, across everything you take. From 200 mg a day the engine warns you; from 400 mg it blocks the plan.
Engine rule R1 adds up the caffeine from anhydrous caffeine, green coffee, green tea, mate and guarana. From 200 mg a day it warns you; from 400 mg it blocks the plan. If you drink mate every day, our file asks for it to come off your budget.
Trouble sleeping, anxiety, a fast heartbeat or palpitations, tremor, nervousness, reflux and passing more urine. Our file puts acute toxicity above 1 g, and records the severe overdoses as coming from concentrated anhydrous powder.
Avoid it with symptomatic arrhythmias, and take particular care with any heart condition. Avoid it or cut it down with anxiety or panic disorder, and avoid it with reflux or a peptic ulcer. In pregnancy and breastfeeding, total caffeine should stay at 200 mg a day or less, and none of our three caffeine formulas is served then. Our label warnings say to avoid it under 18; our file rules out supplementation under 12 and, for adolescents, sets no more than 3 mg per kilo of body weight a day. Take care with liver or kidney disease, with glaucoma, where it can raise the pressure in the eye, if you take anticoagulants, and if you take psychiatric medication, where our file names lithium and clozapine. With histamine intolerance, note that caffeine is documented to inhibit DAO, the enzyme that breaks histamine down. It can cause nervousness, trouble sleeping and palpitations, and the recommended total for healthy adults is 400 mg a day at most. The label warning our file requires for added caffeine: high caffeine content, not recommended for children or in pregnancy or breastfeeding. Our file lists no specific contraindication for cancer, and it contains none of the fourteen allergens that must be declared in the EU.
WHAT IT REACTS WITH
Documented pairs, not hunches.
Caffeine is one of the 140 ingredients in our library, so it has 139 possible partners. We have documented 22 of them, out of the 443 pairs on file: eight are classed as incompatible, seven need a watch on the dose, three need spacing and four are classed as combinable. Separately, engine rule R2 keeps any stimulant, caffeine included, at least 8 hours away from sedatives such as melatonin, GABA, passionflower or valerian.
Both push heart rate and blood pressure up alongside caffeine. Our file records cardiovascular events with bitter orange and caffeine, and the risk of a hypertensive crisis with yohimbine. Neither is ever formulated with it, and neither is in any of our formulas.
Guarana, green tea, mate and green coffee all contain caffeine, so pairing them with anhydrous caffeine hides a second dose. Their caffeine goes into the same budget, and guarana and green coffee are never formulated with it without recalculating the exact dose. Taurine is kept apart at high doses: above 100 mg of caffeine with more than 1,000 mg of taurine they do not share a cartridge, and if they are combined, caffeine is capped at 75 mg.
Our pair table keeps caffeine at least an hour away from any dose of iron; the file for our iron formula asks for 2 hours from coffee and tea, and that is the rule we follow there. Caffeine never shares a dose with 5-HTP: caffeine goes to the morning, 5-HTP to the night. Activated charcoal binds it and is kept at least 2 hours apart; konjac glucomannan and psyllium husk reduce how much you absorb and are kept at least 1 hour apart.
With ginseng at a full dose, our file suggests lowering caffeine by 25–30%; in Acute energy they sit together at 200 mg of ginseng and 75 mg of caffeine, and the formula keeps the 75 mg for now. With more than 200 mg of rhodiola, caffeine is capped at 75 mg. Echinacea blocks the liver enzyme that clears caffeine and raises its levels by about 30%, so the two are not formulated together at high caffeine doses. With huperzine A, epilepsy gets a hard flag and sleep is monitored. With cordyceps, blood pressure is watched if yours runs high, and above 300 mg of caffeine a day, calcium loss is monitored after the menopause or with osteoporosis.
Our library classes these four as working alongside caffeine. L-theanine sits next to it at 2:1 in Cognitive & focus, the ratio our file recommends, and vitamin B6 sits next to it in Acute energy. None of this is an authorised claim for the pair.
Our drug table documents two. With MAOIs such as phenelzine or tranylcypromine, caffeine can precipitate a hypertensive crisis and is kept under 200 mg a day. Theophylline is a related drug whose levels caffeine raises, so the two are not combined at high doses. Our ingredient file also lists warfarin, SSRIs and SNRIs, lithium, clozapine, anticonvulsants such as phenytoin and carbamazepine, beta-agonists and decongestants such as pseudoephedrine, and oral contraceptives. Quinolone antibiotics such as ciprofloxacin, and fluvoxamine, raise caffeine levels, fluvoxamine up to fivefold.
Only two of caffeine's medication interactions are in our drug table; the rest of that list comes from its own file, not from checked pairs. Creatine sits next to caffeine in Pre-workout, and our file describes the studies on the pair as mixed, but it is not yet a documented pair; neither is ephedrine. Across the library, 443 of the 9,730 possible pairs are documented, which is 4.55%. The rest are not "safe", they are simply unchecked, and we would rather write that down than let the number look like a badge.Only two of caffeine's medication interactions are in our drug table. Across the library, 443 of the 9,730 possible pairs are documented, which is 4.55%. The rest are not safe, they are simply unchecked.
SOURCES
Everything on this page, with its reference.
Reviewed by VION nutrition team · last reviewed 16 September 2026Read the introduction to Caffeine →
140 INGREDIENTS · 64 IN USE TODAY
Every one of them has a page like this.
What it is, what we are allowed to say about it, which formulas carry it, what it reacts with and where each of those statements comes from. No proprietary blends, no hidden amounts.