Three years ago, a 23-year-old college athlete collapsed during training. The autopsy later pointed to a pre-workout supplement containing DMAA — a synthetic stimulant compound the FDA had been issuing warnings about since 2012. The product had a label. It had a Supplement Facts panel. It just didn’t tell the full story.
That case isn’t unique. And the ingredient problem at the center of it — opacity around what’s actually inside pre-workout products — still hasn’t been fully resolved.
Pre-workout supplements are one of the fastest-growing categories in sports nutrition, a market now valued at more than $13 billion globally. Walk into any gym or scroll through Amazon, and you’ll find dozens of brightly labeled tubs promising more energy, better pumps, and faster recovery. What you won’t always find is a clear, honest accounting of exactly what you’re putting in your body.
What “Proprietary Blend” Actually Means on a Label
Under 21 CFR Part 101.36 — the federal regulation governing dietary supplement labeling — manufacturers are required to list all dietary ingredients in their product. But when those ingredients are grouped together under a “proprietary blend,” the manufacturer only has to disclose the total combined weight of the blend. Not the amount of each individual ingredient.
So that label showing “Performance Matrix — 7,500 mg” followed by eight ingredients? Those eight could be distributed in any proportion the company chooses. The first ingredient might account for 7,000mg of that total. The last might be 50mg. You simply cannot tell.
This isn’t a gray area or a loophole someone found by accident. It’s explicitly permitted under current law — and it traces directly back to the Dietary Supplement Health and Education Act of 1994 (DSHEA). That law fundamentally shifted how supplements are regulated in the US: rather than requiring manufacturers to demonstrate a product is safe before it reaches shelves, it placed the burden on the FDA to prove a product is dangerous before it can be removed from the market.
The practical result is a market where companies can — and do — “fairy dust” their formulas. That’s the industry term for including a trendy ingredient at a clinically meaningless dose, just to get the name on the label. A peer-reviewed study might establish that 8g of citrulline malate meaningfully improves blood flow and reduces post-exercise muscle soreness. A proprietary blend might contain 200mg of it, buried inside a 6g matrix. The label looks identical to the customer.
The Stimulant Problem Goes Well Beyond Caffeine
Most consumers know pre-workouts contain caffeine. Fewer know how much. Servings range widely across brands, but it’s common to find products delivering 200–400mg of caffeine per serving. The FDA’s guidance for healthy adults places 400mg per day as a reasonable upper limit. That means a single scoop of a high-stimulant product can hit your entire daily ceiling — before your morning coffee, before anything else.
Caffeine at moderate doses isn’t inherently dangerous for most healthy people. But the stimulant picture in pre-workouts is more complicated than caffeine alone.
DMAA — 1,3-dimethylamylamine — is a synthetic compound that the FDA has formally stated is not lawfully marketed as a dietary ingredient. The agency began issuing warning letters about DMAA-containing products in 2012 after adverse event reports began accumulating: heart attacks, hemorrhagic stroke, and in some cases death. More than a decade of enforcement actions later, products containing DMAA or its analogues continue to surface. The compound gets reformulated under different names — 1,3-DMAA, methylhexaneamine, geranamine — and new products appear before regulators can catch up.
DMHA (2-aminoisoheptane) followed a nearly identical pattern. Synephrine, an alkaloid from bitter orange, is another one to know — it can raise blood pressure and interact dangerously with other stimulants. And because proprietary blends don’t require individual amounts, a consumer buying a $60 tub labeled “Advanced Energy Complex” can’t determine whether they’re getting a cautious dose or a concerning one.
The commercial logic behind this isn’t complicated. Stimulant-based pre-workouts sell on the intensity of the user experience — the skin tingling from beta-alanine, the sharp focus from caffeine. When a product delivers that sensation, customers repurchase. When a manufacturer cuts the cost by reducing expensive ingredients and quietly substituting something cheaper and more stimulating, the customer often can’t see it on paper. They just feel it. Sometimes in ways they don’t expect.
What Third-Party Testing Keeps Revealing
To be clear: the supplement certification ecosystem genuinely works when it’s used. NSF Certified for Sport — one of the most rigorous third-party programs in the industry — tests products for over 270 substances prohibited by WADA and other major sports organizations, and independently verifies that what’s listed on the label matches what’s actually in the bottle at the declared dose. Informed Sport offers similar batch-level testing. Products carrying either seal have cleared a meaningful bar.
The problem is that most pre-workouts on the market carry neither.
Third-party labs and consumer testing organizations that audit sports nutrition products — including ConsumerLab.com and university-based nutrition research teams — consistently find two categories of issues in pre-workouts:
Label inaccuracy. Caffeine content frequently differs from the declared amount by 20–30% or more in either direction. Ingredients that appear prominently on the front-of-pack are sometimes present at doses far below what any clinical study would consider effective.
Undeclared ingredients. The FDA’s own Tainted Products Marketed as Dietary Supplements database — which is publicly searchable on FDA.gov — lists hundreds of products found to contain undeclared pharmaceuticals or controlled substances. Muscle-building and energy supplements are two of the three most heavily represented categories in that database. Pre-workouts span both.
None of this means every pre-workout is unsafe. The majority are probably fine in healthy adults using them as directed. But “probably fine” is a lower bar than most consumers expect from a product they’re spending $50–$80 on and consuming before every training session.
How to Actually Evaluate What You’re Buying
If you’re going to use a pre-workout, here’s what separates products worth trusting from those worth skipping.
Look for a fully disclosed label. A growing number of brands voluntarily list each ingredient at its individual dose — no combined totals, no proprietary blends. This is sometimes marketed as a “transparent formula” or “fully dosed label,” and it’s one of the more meaningful claims a supplement company can make. When you can see that a product contains 8,000mg of citrulline malate, 3,200mg of beta-alanine, and 200mg of caffeine, you can actually cross-reference those against the research literature.
Check for third-party certification. NSF Certified for Sport or Informed Sport seals mean an independent organization has verified purity and label accuracy. If you’re an athlete subject to anti-doping rules, these certifications aren’t a preference — they’re a necessity. If you’re a recreational gym-goer, they still tell you something useful: someone other than the manufacturer has checked the work.
Research each stimulant by name. A quick search for “DMAA FDA warning” or “DMHA adverse events” takes about 90 seconds and will tell you whether an ingredient in your product has a regulatory history worth knowing about. If it does, that’s information you should have before you open the tub.
Add up your total daily caffeine. Coffee, tea, pre-workout, energy drinks — it all counts. If you’re consistently consuming close to 400mg before noon, adding a full serving of a high-stimulant pre-workout is likely more than your cardiovascular system needs.
Start with half a serving, regardless of what the label says. Individual sensitivity to stimulants varies significantly. What’s a standard dose for one person can trigger heart palpitations, anxiety, or worse in another. A half-serving test tells you more about your personal response than any label claim can.
The due diligence you’re doing right now — reading this, asking questions, looking closer — is exactly the kind of work the current regulatory framework places on you as a consumer. Under DSHEA, the FDA can’t require a pre-workout to be proven safe before it hits shelves. That means the research phase is yours to own.
The label on your pre-workout is a legal document, not a complete safety guarantee. Treat it that way.
Written by Nour Abochama, Host & Quality Control Expert, Nourify & Beautify. Learn more about our team
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- How ISO 17025 Labs Verify Supplement Label Claims — The analytical methods behind third-party supplement certifications, explained by the scientists who run them.
- Raw Material Supplier Qualification: Why Supplement Safety Starts Before Manufacturing — How ingredient sourcing and supplier audits determine what actually ends up in your finished product.
