What Should You Avoid in Pre-Workout? A Guide to Unsafe Ingredients

December 28, 2025 •

4 min read

According to a 2019 study, over half of regular pre-workout users report experiencing negative side effects, yet many continue to use them. Navigating the supplement aisle can be challenging, which is why it's crucial to understand what you should avoid in pre-workout to ensure your health and optimize your fitness goals.

Quick Summary

This guide details the problematic ingredients often found in pre-workout supplements, such as excessive caffeine, artificial additives, and non-transparent proprietary blends. By identifying these components, consumers can make safer, more informed choices to enhance their workouts without compromising their well-being.

Key Points

Excessive Caffeine: Avoid pre-workouts with high doses (over 400 mg) per serving to prevent jitters, anxiety, and sleep disruption.
Proprietary Blends: Steer clear of formulas with proprietary blends, as they hide individual ingredient amounts and dosages, making it impossible to verify effectiveness or safety.
Artificial Sweeteners and Colors: Avoid synthetic additives like aspartame, sucralose, and artificial dyes, which can cause digestive issues and offer no performance benefit.
Unnecessary Fillers: Be cautious of products that use cheap fillers to bulk up the formula without adding functional value, diluting the potency of active ingredients.
Lack of Third-Party Testing: Look for supplements certified by organizations like Informed Sport or NSF to ensure they are free of contaminants and banned substances.
Individual Tolerance: Recognize that everyone reacts differently to ingredients. Start with small doses to assess your tolerance and choose stim-free options if sensitive to caffeine.

The Dangers of Excessive and Unregulated Ingredients

While many pre-workout supplements can be beneficial, the industry's loose regulation means some products contain ingredients that can be ineffective at best and harmful at worst. Excessive stimulants and undisclosed formulas are particularly common culprits that can lead to unpleasant or dangerous health issues.

Excessive Caffeine and Other Stimulants

Caffeine is a potent and popular pre-workout ingredient for its ability to boost energy and focus. However, too much of a good thing can quickly become problematic. The FDA advises that up to 400 mg of caffeine daily is safe for most adults, but many pre-workout formulas can contain anywhere from 100 mg to over 400 mg in a single scoop.

Jitters and Anxiety: High doses of caffeine can overstimulate the central nervous system, leading to anxiety, jitteriness, and restlessness, which can impair concentration and performance.
Cardiovascular Strain: Excessive caffeine raises heart rate and blood pressure, posing a risk, especially for individuals with pre-existing heart conditions. In rare cases, high stimulant intake has been linked to severe cardiovascular events.
Sleep Disruption: Taking a high-stimulant pre-workout in the afternoon or evening can significantly disrupt sleep patterns, negatively impacting recovery. Caffeine has a long half-life, with traces remaining in the body for hours after consumption.
Adrenal Fatigue and Tolerance: Consistent, high-dose stimulant use can lead to tolerance, requiring even higher doses for the same effect, which can result in adrenal fatigue and a cycle of dependency.

Proprietary Blends

Proprietary blends are a major red flag in the supplement industry. These blends list a group of ingredients with a total combined dosage, but hide the specific amount of each individual component.

Undisclosed Dosages: Without transparency, it's impossible to know if you're receiving a clinically effective dose of the beneficial ingredients. Companies can include cheap fillers and only a trace amount of expensive, high-quality ingredients to cut costs.
Risk of Banned Substances: Lax regulation allows some manufacturers to include banned or untested stimulants in proprietary blends, which can lead to failed drug tests for competitive athletes and pose serious health risks for all users.
Inconsistent Potency: The actual caffeine content in proprietary blends can vary wildly, even within the same batch, increasing the risk of an accidental overdose.

Artificial Additives and Ineffective Fillers

Many pre-workouts are filled with synthetic ingredients that serve no performance-enhancing purpose but can cause significant health problems.

Artificial Sweeteners: Ingredients like aspartame and sucralose are calorie-free but can cause digestive issues, such as bloating, gas, and stomach cramps. There is also ongoing debate about their long-term health effects on gut microbiome and metabolic health.
Artificial Colors and Preservatives: Synthetic dyes and preservatives offer no performance benefits and have been linked to allergic reactions and other negative health effects. For example, studies have connected some artificial colors to hyperactivity in children.
Ineffective Doses of Quality Ingredients: Some products include well-regarded ingredients like creatine or citrulline, but at such low doses that they provide no real benefit. The formula relies on the high caffeine content and flashy marketing to sell.

Comparison Table: Safe vs. Unsafe Pre-Workout Features


Feature	Safe Pre-Workout	Unsafe Pre-Workout
Label Transparency	Lists all ingredients with specific, clinically effective dosages.	Uses proprietary blends, hiding individual ingredient amounts.
Caffeine Content	Moderate, within safe limits (e.g., 100-200 mg), with stim-free options available.	Excessively high doses (300+ mg per scoop) or undisclosed quantities.
Additives	Uses natural flavors and colors, or is unflavored.	Contains artificial sweeteners (aspartame, sucralose) and synthetic colors (Red 40).
Safety Assurance	Third-party tested and certified (e.g., Informed Sport, NSF) for purity.	Lacks third-party certifications, raising risk of contaminants.
Active Ingredients	Contains research-backed ingredients at effective doses (e.g., CarnoSyn® Beta-Alanine).	Includes cheap, generic, or under-dosed ingredients to bulk up the product.

Natural Alternatives to Traditional Pre-Workout

For many, a balanced diet and proper hydration are all that's needed to fuel an effective workout. For those seeking an extra boost without the risks of synthetic products, natural options are available.

Coffee or Green Tea: Provides a controlled dose of caffeine from a natural source. You know exactly what you're consuming, and can adjust the strength to your personal tolerance.
Beetroot Juice: A natural source of nitrates, which are converted to nitric oxide in the body to increase blood flow and muscle oxygenation, leading to better endurance.
L-Citrulline: An amino acid that also increases nitric oxide production. It is available as a standalone supplement and is a great way to get a 'pump' without stimulants.
Healthy Snack: A small meal with simple carbohydrates and protein, such as a banana with a tablespoon of peanut butter or a rice cake with jam, can provide clean energy without a crash.

Conclusion

Making informed choices about supplementation is key to both performance and long-term health. Knowing what you should avoid in pre-workout supplements empowers you to skip the unnecessary risks associated with excessive stimulants, undisclosed proprietary blends, and artificial additives. By prioritizing transparent labels, proper dosages, and your body's individual needs, you can achieve your fitness goals safely and effectively. Whether you opt for a clean, third-party certified product or choose natural alternatives, you're taking control of your fitness journey and prioritizing your well-being. Consult with a healthcare provider before starting any new supplement, especially if you have pre-existing health conditions or are taking other medications.

Optional Outbound Link: Understanding Pre-Workout Ingredients for Beginners

Frequently Asked Questions

A high dose of caffeine in pre-workout is generally considered to be over 200-300 mg per serving, especially for individuals sensitive to stimulants. Some formulas contain even more, which can lead to negative side effects.

You should avoid proprietary blends because they do not disclose the exact amount of each ingredient, allowing manufacturers to include ineffective doses of expensive ingredients while padding the formula with cheap fillers. This lack of transparency also makes it difficult to assess potential risks.

Yes, artificial sweeteners like aspartame and sucralose are known to cause digestive issues in some individuals, including bloating, gas, and stomach cramps. High intake of sugar alcohols can also trigger diarrhea.

To avoid jitters, you can choose a low-caffeine or stimulant-free pre-workout, reduce your dosage, or split the dose. You can also build your tolerance slowly by starting with a small amount.

Yes, natural alternatives include drinking a cup of coffee or green tea, consuming beetroot juice for nitric oxide, or having a small, balanced snack like a banana with peanut butter for a clean energy boost.

Without third-party certification from organizations like Informed Sport or NSF, you risk consuming a product with inaccurate labeling, contaminants, or even illegal or banned substances. This is especially important for competitive athletes.

Yes, formulas with excessive stimulants and high caffeine content can increase heart rate and blood pressure, which can be dangerous for individuals with pre-existing heart conditions. Always consult a healthcare professional if you have concerns.