Few things beat the feeling of smashing a workout. You feel accomplished, invigorated, powerful, and strong. But there's sometimes a fine line between maximizing your training intensity and going overboard—especially if you're throwing supplements into the mix.

For anyone looking to crank their workout up a notch, pre-workout is generally the go-to supplement. They boost energy, maximize focus and concentration, and mitigate fatigue. But what happens if you knock back your pre-workout only to feel like you're about to yak?

Depending on the dosage and the ingredients, some pre-workout supplements can make you feel like throwing up—but it doesn't have to be that way. In this article, we're breaking down why pre-workout can make you feel sick and what you can do to prevent it.

What Is Pre-Workout And Why Should I Use It?

If you frequent the gym, you've probably heard about pre-workouts. They're a class of supplements intended to be taken before training that contains a blend of ingredients purported to enhance athletic performance and augment training adaptations when consumed long-term 1, 2.

A large body of evidence suggests that acute consumption of pre-workouts has positive effects on muscular endurance. Still, the evidence to support its impact on force and power production is mixed.

However, when combined with a periodized resistance training program, pre-workouts can elicit beneficial adaptations to improve body composition and greater lean mass.

Some of the most common pre-workout ingredients include 1:

  • Caffeine
  • Beta-alanine
  • Amino acids
  • Citrulline
  • Creatine
  • Vitamins and minerals

There's no end to the benefit of taking a pre-workout. Depending on your end goal and how you train, pre-workouts can improve endurance and stamina or target muscle growth and strength. Here are some benefits associated with pre-workouts:

  • Greater muscle growth
  • More strength
  • Stronger endurance
  • More energy
  • Better focus and mental clarity
  • Faster recovery

That said, what's in your pre-workout will dictate what effects it has.

Common Side Effects Of Pre-Workout Supplements

Although there are many benefits linked to pre-workout, some significant downfalls can result in performance decrements if you're not careful. Here are a few of the most common side effects experienced from ingesting pre-workouts.

1. Jitters

If you're feeling nervous and jittery after taking a pre-workout, you can blame caffeine. As a potent central nervous system stimulant, caffeine doesn't inherently give you more energy as much as it masks fatigue. Caffeine is an adenosine antagonist that binds to adenosine receptors in the brain and blocks the action of adenosine.

Caffeine causes neural excitation in the brain, which the pituitary gland sees as an emergency or stress, and therefore stimulates the adrenal glands to release adrenaline 3.

Increased circulating levels of adrenaline result in changes in blood pressure, blood flow, and ventilation, all of which can result in that nervous, anxious, jittery feeling 4, 5. In general, you're feeling heavily over-stimulated, which tanks your focus, concentration, and likely your ability to have a good workout.

2. Bloating (water retention)

Although bloating may not seem like the worst side effect to experience from a pre-workout, it can be uncomfortable. For the most part, bloating happens to some people after ingestion of creatine—a compound touted to boost muscle growth and increase exercise capacity 6.

Creatine is an osmotically active substance. The consumption of creatine alters intracellular osmotic pressure, causing water movement into cells and leading to increased water retention and weight gain 7.

But despite the unpleasant side effects of high-dose creatine, it's exceptionally safe. That said, bloating typically occurs during creatine loading protocols and subsides when doses drop to maintenance levels.

3. Headaches

Headaches are another common side effect of certain ingredients in pre-workout supplements. Ingredients that cause vasodilation in the brain—arginine, citrulline, beta-alanine, and other nitric oxide boosters—can cause headaches due to vascular changes.

Studies suggest that nitric oxide (NO) may be involved in migraines and different types of vascular headaches since glyceryl trinitrate (an NO donor) and histamine (activates endothelial NO production) both cause pulsating headaches that exhibit characteristics of migraines 8. And blocking nitric oxide synthases has been shown to alleviate migraine symptoms 9.

That said, nitric oxide also plays a critical role in athletic performance and promoting the 'pump' that lifters crave. Still, if you're not someone who frequently experiences migraines or headaches, you'll likely do fine with NO boosters.

4. Digestive Upset

Last but not least, we get to the digestive upset, which most commonly manifests as nausea. Several common ingredients in pre-workout supplements—sodium bicarbonate, magnesium, creatine, and caffeine—can all contribute to digestive side effects via different mechanisms.

However, caffeine has a strong diuretic effect that can increase the risk of nausea and diarrhea by pulling water out of the bloodstream and into the GI tract.

The acidity of coffee can also make some people feel sick. And especially if you're consuming a high caffeine pre-workout on an empty stomach, it absorbs faster and can lead to queasiness.

Can Pre-Workout Make You Sick?

The answer to this highly depends on what's in your pre-workout. If you're taking a supplement that's heavy on caffeine and taking it on an empty stomach, you could feel a bit nauseous. It's absorbing rapidly and spiking hormone levels, leading to some pretty nasty side effects.

If your pre-workout contains no caffeine or minimal amounts combined with other nutritionally sound ingredients, it's not likely to elicit any drastic gastrointestinal effects.

In any case, keep an eye on what's in your pre-workout, and if you notice it's making you feel sick on an empty stomach, try it after a meal. Swap it out for something else if it's still making you feel sick.

With that said, proprietary blends are something to watch for if you're feeling sick after taking a pre-workout.

Because blends are a "manufacturer's secret," they're not required to disclose the number of ingredients in the blend; only list them from greatest amounts to least. With any supplement, you want to know exactly what you're getting, not guess what's hidden under a proprietary blend.

3 Reasons To Pick A Quality Pre-Workout

1. You Know Precisely What You're Getting

With a reputable pre-workout, you should never have to guess how much of an ingredient you're getting. You want to know exactly how much of everything is in each serving.

If you're feeling sick with a single scoop, you can hone in on exactly what's causing you to feel that way and what ingredient you need a lower dose of to prevent sickness.

2. Science-Backed Ingredients

As with a supplement, you want to ensure that everything you're putting into your body is research-backed and effective, without any adverse effects.

With Pre Lab Pro, you're getting best-in-class ingredients that are clean, safe, and deliver the greatest fitness results. It's third-party tested to provide objective proof of nutritional purity, potency and cleanliness, guaranteeing that what's in the bottle matches what's on the label.

3. Fewer Side Effects

You're getting maximum results with minimal side effects, high-quality ingredients, and precision-tuned doses. Excessive doses of stimulants lead to performance decrements and gastrointestinal side effects, but they can also lead to long-term burnout.

With Pre Lab Pro, you get a moderate dose of caffeine for enhanced performance without going overboard. And with Pre Lab Pro's innovative stack of nutrients, you can unlock all the performance benefits of caffeine with no downsides.

It's the cleanest, smartest, and most effective pre-workout.


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  3. Van Soeren M, Mohr T, Kjaer M, Graham TE. Acute effects of caffeine ingestion at rest in humans with impaired epinephrine responses. J Appl Physiol (1985). 1996;80(3):999-1005.
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