Compare stim-free pre-workouts on what is actually in the scoop: the amount of each ingredient per full-strength serving, whether the label discloses every amount, and the cost per serving. They contain no caffeine, so they're one option if you train late, are sensitive to caffeine or already drink plenty of coffee, but no caffeine doesn't mean every formula is the same.
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What is a stim-free pre-workout?
A stim-free (non-stim) pre-workout is one made without caffeine or other stimulants. Instead, these products are usually built around ingredients such as citrulline, arginine, beta-alanine, taurine, glycerol or beetroot, and this collection includes all of those types as well as single-ingredient powders and capsules.
"Stim-free" is a description, not a regulated term, so read the full ingredient list. Products with added caffeine must state it on the label: a food supplement with added caffeine must carry the warning "Contains caffeine. Not recommended for children or pregnant women". If you see that line, it isn't stim-free.
Does stim-free pre-workout work?
It depends on the ingredients and the amounts, and the evidence is mixed. A review of multi-ingredient pre-workouts in the Journal of the International Society of Sports Nutrition found that citrulline doses in these products are generally far lower than those that have shown effects in studies, and that most evidence suggests arginine has limited effect on blood flow or exercise performance.
The same review found dietary nitrate (the compound in beetroot) appears to help endurance and high-intensity exercise at doses of 300mg or more. No authorised health claims exist for citrulline, arginine, nitrate, beetroot or taurine in the GB register of permitted claims, so we don't say these products improve your performance. "Where evidence is limited or inconclusive, we should say so openly," says Andy Arshad, who runs SupplementHQ.
Is caffeine-free pre-workout good for evening training?
It's one way to avoid caffeine late in the day. EFSA (the European Food Safety Authority) says single doses of 100mg of caffeine may affect sleep in some adults, particularly close to bedtime, and many caffeinated pre-workouts contain more than that in one serving.
"I believe stimulant-free pre-workouts deserve more attention, particularly for evening gym users, people sensitive to caffeine or those already consuming caffeine throughout the day," says Andy.
Stim-free vs regular pre-workout: what's the difference?
The main difference is caffeine. A regular pre-workout contains caffeine, sometimes a lot of it; a stim-free one contains none, and the other ingredients are often similar.
| What to check | Stim-free | Caffeinated |
|---|---|---|
| Caffeine per serving | None | Varies widely: check the label |
| Counts towards your daily caffeine | No | Yes, along with tea, coffee and energy drinks |
| Caffeine warning on the label | No | Yes, with the amount per daily portion |
| Common other ingredients | Citrulline, beta-alanine, arginine, glycerol, beetroot | Often the same, plus caffeine |
The ISSN says caffeine itself has a well-studied effect on exercise at moderate doses, and that people respond to it very differently. If you want caffeine, compare caffeine levels in our moderate-stim range and the wider pre-workout collection.
Why does my stim-free pre-workout make me tingle?
That's most likely beta-alanine, which is in many stim-free formulas. The ISSN says the only reported side effect of beta-alanine is paraesthesia (tingling), and that it can be reduced by using smaller divided doses or a sustained-release form.
The same position stand describes 4 to 6g a day, taken for at least 2 to 4 weeks, as the amount used in research. Check how much beta-alanine one serving provides, or compare single-ingredient beta-alanine products.
How do you compare stim-free pre-workouts?
Compare the amount of each ingredient per full-strength serving, then the cost per serving. Labels that list every amount make this possible; proprietary blends, which give one total for several ingredients, don't.
"Some brands also use proprietary blends, making it difficult to establish exactly how much of each active ingredient you're getting. Others clearly disclose their ingredient quantities, making comparisons much easier," says Andy.
How to compare value (example figures, not real products): a £28 tub with 20 full servings costs £1.40 a serving and lists 6g of citrulline per serving, so 6g of citrulline costs £1.40. A £20 tub with 40 servings costs 50p a serving but lists 1.5g, so getting 6g would take four servings at £2. The cheaper tub is the more expensive way to get the same amount of citrulline.
Is stim-free pre-workout safe?
A review of multi-ingredient pre-workouts found they appear relatively safe in studies, but most of those studies lasted less than eight weeks. The authors also warned that some formulations may contain banned substances, either as ingredients or as contaminants.
Follow the directions on the label and don't take more than one pre-workout product at a time. If you have a medical condition, take medication, or are pregnant or breastfeeding, speak to your GP or pharmacist before using any pre-workout.
We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.
Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.