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How much citrulline should be in a pre-workout?

By Jose Pollman · Published · Numbers from the 105 pre-workout labels on the site, recounted every time the site is updated

The short answer

  • Studies gave 6–8 g of citrulline malate 40–60 minutes before training. Counted as L-citrulline, that's 4–5.33 g.
  • 83 of 105 pre-workouts on the site list citrulline. 65 give an amount we can count; the middle one has 4 g of L-citrulline a serving.
  • 47 of 65 reach 4 g in one serving.
  • The form matters. 6 g of citrulline malate 2:1 holds 4 g of citrulline; 6 g of plain L-citrulline holds all 6 g. 6 labels print "citrulline malate" with no ratio, so the citrulline in them can't be worked out.
  • 12 list citrulline without an amount, mostly inside a proprietary blend. In 10 of those, the blend is too small to hold 4 g of it.
Studies: 4–5.33 g0 g2 g4 g6 g8 g10 gEach dot: one product, per serving
L-citrulline in one serving, one dot per label: the 65 pre-workouts on the site that give an amount we can count. Green dots reach 4 g (47 labels); orange dots are below it. The shaded band is the range studies used, counted as citrulline.

Where 4 g comes from

The studies on citrulline and training mostly gave citrulline malate, not plain citrulline, as one dose before a session. A meta-analysis of eight double-blind studies (137 people) summed it up as "6–8 g of CitMal 40–60 min before exercise", which gave about three more repetitions to failure than a placebo, a small effect; for upper-body exercises alone, the difference wasn't significant (Vårvik et al., 2021). A critical review found that a single 8 g dose was "the most common approach", that the results were "equivocal", and that until better studies are done, whether it improves performance "remains ambiguous" (Gough et al., 2021).

That's why we grade the evidence for citrulline as weak, and why a citrulline verdict on this site is about the dose only. We count L-citrulline: the two thirds of 2:1 citrulline malate that is citrulline. So 6–8 g of citrulline malate becomes 4–5.33 g of L-citrulline, and a label below 4 g is marked Below research dose.

Citrulline or citrulline malate: the same grams aren't the same dose

Citrulline malate is citrulline bound with malic acid. "2:1" means two parts citrulline to one part malic acid, so a third of the weight isn't citrulline. Labels print it in three ways, and the same 6 g on the panel means three different things:

L-citrulline Malic acid Share not known 4 g, the low end of the studies

  • L-Citrulline 6 g6 g of citrulline
  • Citrulline Malate 2:1 6 g4 g of citrulline
  • Citrulline Malate 6 gnot known: no ratio
The same 6 g printed three ways. The red line is 4 g of citrulline, the low end of what studies gave. With no ratio printed, we don't guess one.

Of the 83 pre-workouts that list citrulline, 52 print plain L-citrulline and 18 print citrulline malate 2:1, which we count as two thirds citrulline. 2 print citrulline nitrate, which we count as the 73.5% of its weight that is citrulline (Cellucor C4 Extreme, RYSE Godzilla). The other 11 print citrulline malate with no ratio, or more than one form.

This is where the form catches people out. 2 labels print 4 g or more of citrulline malate 2:1 but hold less than 4 g of citrulline: Alpha Lion SuperHuman Pump (4 g printed, 2.67 g of citrulline) and Swolverine PRE (5 g printed, 3.33 g of citrulline).

6 labels print "citrulline malate" with no ratio at all: Animal Fury, Gnarly Pre-Workout, Just Ingredients PreWorkout, JYM Pre JYM, Legion Pulse Stim-Free and Old School Labs Vintage Blast. Without a ratio, the label doesn't say how much of the weight is citrulline, so we don't assume 2:1. These are marked Not graded for citrulline until the label says. The same review also mentions "quality control issues" with some manufacturers' stated citrulline:malate ratios (Gough et al., 2021). A label's ratio is the maker's claim; we count it as printed, and only a lab test could check it.

It counts by the workout

Unlike beta-alanine or creatine, which build up with daily use, citrulline was studied as one dose before training. So the amount in the serving you take before a session is the number to compare. If a label's serving is two scoops, one scoop holds half. 5 labels here print their citrulline for a two-scoop serving, and none of them reaches 4 g in one scoop: Apollon Nutrition Bare Knuckle (4 g in two scoops), Legion Pulse (5.33 g in two scoops), PEScience High Volume (4 g in two scoops), PEScience Prolific (6 g in two scoops) and Thorne Advanced Pre-Workout (5 g in two scoops).

These are the pre-workouts people most often search for by name, with the L-citrulline in one serving as their labels give it:

Studies: 4–5.33 g of citrulline Amount not known

L-citrulline in one serving. Green reaches 4 g, orange is below it, and striped bars are amounts the label doesn't let us work out. The shaded band is the 4–5.33 g studies used, counted as citrulline.

One brand can sit on both sides of the line: Cellucor's C4 Original and C4 Ultimate are different labels with different amounts. Check the exact product, not the brand. The highest amount on the site is 10 g, in Kaged Pre-Kaged Elite.

When citrulline is inside a blend

A proprietary blend prints one weight for several ingredients together. US rules make the label list a blend's ingredients from heaviest to lightest, so even without an amount there is a ceiling: the second ingredient can't be more than half of the blend, the third no more than a third, and so on. That gives the most citrulline each of these blends can hold. The product page marks it Hidden in a blend and shows the range.

The most citrulline the blend can hold 4 g, the low end of the studies

The most citrulline each blend can hold in one serving, from the blend's weight and where citrulline sits in its list. The red line is 4 g. Lighter bars can't reach it.

In 10 of these 11, even the ceiling is below 4 g. The other could reach it, but the label doesn't say whether it does. One more label, GAT Sport Nitraflex, lists citrulline with no amount and no blend weight we can use.

Is there a "too much"?

The studies we use go up to 8 g of citrulline malate, 5.33 g of citrulline. We haven't set an upper limit for citrulline, so no product on the site is marked "too much" for it, and we don't guess one. 16 of the 65 labels with an amount give more than 5.33 g of citrulline in a serving, above the top of the studies we use; that's more than was tested, not a verdict.

Reading your own tub

  1. Find citrulline on the facts panel, and read the exact name: L-citrulline, citrulline malate with a ratio, or citrulline malate with none.
  2. For 2:1 citrulline malate, take two thirds of the amount: that's the citrulline. With no ratio, the label doesn't tell you.
  3. Check the amount is for the serving you take, and how many scoops make that serving.
  4. If it's inside a blend with no amount, look at the blend's weight and its place in the list: that's the most it can hold.
  5. Compare the citrulline with the 4–5.33 g studies used (6–8 g of citrulline malate).

Or search for your product on the pre-workouts page, or paste its label, and we'll do the counting, with every step shown. The L-citrulline guide has the full research dose and sources.

Sources

  • Vårvik FT, Bjørnsen T, Gonzalez AM. Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis. Int J Sport Nutr Exerc Metab. 2021;31(4):350-358. doi:10.1123/ijsnem.2020-0295
  • Gough LA, Sparks SA, McNaughton LR, et al. A critical review of citrulline malate supplementation and exercise performance. Eur J Appl Physiol. 2021;121(12):3283-3295. doi:10.1007/s00421-021-04774-6
  • Label amounts: each product's label as imported, with its source and date on the product page. Blend ceilings follow 21 CFR 101.36, which lists blend ingredients by weight.
  • How we count citrulline malate and citrulline nitrate, and every other ingredient: our methodology.