Man holding dumbbells and sitting on a throne of pre-workout

Is Pre-Workout Dangerous? What to Know Before Taking

Is pre-workout for bros who don't care about their health, or anybody trying to hit a PR?
By Will Price
May 18, 2024

Pre-workout powder, or “pre” as the gym bro natives call it, is a water-soluble mix of workout-enhancing ingredients you can buy at any supplement store, and even in some grocery stores. Yet, despite its general usefulness and widespread availability, pre-workout carries with it a fairly intense stigma as an unsafe—or at least somewhat jarring—workout supplement. Is pre-workout dangerous? Here’s what you should know.

Is Pre-Workout Dangerous?

The short answer is no, but with caveats—some obvious, some not so much. There is good science supporting pre-workout as a workout booster (1, 2, 3, 4), but it may not be fit for everyone due to a few potential side effects of taking it. There are three primary negative reactions to the product, which vary in intensity and prevalence based on the exact pre-workout a person is taking (they’re not all the same).  


In this case, jitters are a catch-all for overstimulation. There is often more than one stimulant in any given pre-workout, but the most common (and usually the biggest serving) is good old caffeine. You’ll find different levels of caffeine across the pre-workout market, but most caffeinated options hover between 300 and 500mg of the stuff per serving of pre-workout. That is roughly 3 to 5 times the potency of a cup of coffee. 

For those who are more sensitive to caffeine, this can easily lead to increased heart rate, high blood pressure, nausea, and stomach discomfort (most often manifested as diarrhea). But, it should be said, even people who don’t have a problem drinking a couple cups of coffee in the morning should take care of consuming this much caffeine in one go. 

There are non-stimulant versions of pre-workout as well, which increase energy and workout capacity via ingredients like BCAAs, beta alanine, various ATP sources, and so on. 

Water retention

Another very common ingredient in pre-workout is creatine. Creatine does cause minor weight gain in most people, which is often associated with increased water retention. The science linking weight gain, water retention, and creatine isn’t as firm as it could be, but it’s mostly accepted that the substance will add 2 to 4.5 pounds of weight on a person, depending on their size and the dosage (5).

This isn’t really a problem, as we know creatine as one of the very few truly ergogenic supplements (6) we can invest in, but it may be an unwanted consequence that isn’t immediately clear when taking pre-workout. But, just as you can find non-stimulant pre-workout, there are plenty of pre-workout blends that do not include creatine.

Mild reactions

You might have been told a gnarly story about some kind of extreme reaction to pre-workout, but, if you follow recommended serving sizes and don’t consume the stuff too often, the craziest reaction will likely be more mild. Some users may experience a tingling sensation run through their fingers, hands, and feet, which is totally harmless and the result of the body processing beta alanine, which is meant to boost your ability to perform during high-intensity exercises. Again, this feeling doesn’t last and isn’t a genuine concern, though it can be uncomfortable initially. 

The second is a quick rush of blood to the skin, or skin flushing, which is the result of large amounts of niacin often found in pre-workouts. Most people that eat a reasonable diet don’t need more niacin, as we usually get all we need from the meat and whole grains we eat most days. But the amount in pre-workout is quite high, and can cause some red splotches to appear on the skin. Again, this is not a serious health concern, but it can be disconcerting. 

The Bottom Line

Is pre-workout dangerous? If taken within the set serving guidelines, no, pre-workout is perfectly safe. You may experience some passing discomfort in the form of tingling sensations in your hands and feet, or see red splotches appear on your skin, but these are—despite what they sound and look like—not serious health concerns. The majority of the horror stories associated with pre-workout are the result of taking well beyond the set servings. Don’t do that.