Side Effects of Pre-Workout Supplements

Pre-workout supplements are multi-ingredient products used for exercise-enhancing purposes. They’re available in powder form, which you can mix with water and drink before exercise.

These supplements contain amino acids, B vitamins, caffeine, creatine, and a mixture of several ingredients, each with a specific role in performance improvement.

The amounts of these nutrients vary depending on the brand. However, some people develop negative side effects after using pre-workout supplements.

This article explains pre-workout supplements’ side effects, plus how to avoid them.


Beta-alanine is a non-essential amino acid, meaning your body can produce it. It is the key ingredient in many pre-workout supplements.

Beta-alanine helps produce another chemical in the body known as carnosine. Carnosine aids in muscular endurance during high-intensity exercise, which can help you keep your workout going for longer.

The recommended dosage for beta-alanine is 4-6 grams per day. However, taking 6 grams of beta-alanine pre-workout supplement may cause side effects, a condition called paresthesia, which is a sort of tingling sensation in your hands and feet.

While it is a harmless nervous system reaction, it may disturb some people. The most effective way to reduce beta-alanine-related tingling is to divide the 6-gram daily dose into 2 separate 3-gram doses (1, 2, 3, 4).


Niacin (vitamin B3), one of the eight B vitamins, is another ingredient in many pre-workout supplements that can produce minor side effects. Taking 500 mg or more of niacin per day can trigger rashes on the surface of your skin, resulting in red patches.

Niacin plays an important role in energy production and metabolism. However, if you consume a well-balanced diet, niacin supplements do not provide additional benefits.

If you think niacin is affecting you, buy a pre-workout supplement that is niacin-free (5, 6, 7).


Caffeine is a psychoactive stimulant and is the primary ingredient in many pre-workout supplements. According to some studies, caffeine can increase energy output while reducing fatigue during exercise.

However, pre-workout supplements that contain caffeine can have downsides if you consume too much. These include insomnia, nausea, an increased heart rate, drowsiness, headaches, and anxiety.

Most pre-workout supplements can provide up to 500 mg of caffeine per 10 to 30 gram serving size. When compared to pre-workout supplements, 1 cup of 240 ml of coffee contains only 95 mg of caffeine.

Caffeine can affect each person differently, as some people tolerate it better than others do (8, 9, 10, 11).


Citrulline is an amino acid that is found in some foods, like watermelons. The primary benefit of citrulline is that it works by increasing your blood’s nitric oxide levels.

The recommended dose for citrulline malate is 6–8 grams, although many pre-workout supplements offer smaller amounts and may not provide potential benefits.

Pre-workout supplements that provide a high dose of citrulline may cause an increase in blood flow, which affects both your brain and muscles, leading to side effects such as headaches and migraines during exercise.

Decreasing your dosage is the most effective way to reduce your citrulline side effects. If you find you are still struggling with headaches, find a pre-workout supplement that does not contain citrulline (12, 13).


Another popular ingredient in many pre-workout supplements is creatine. Creatine supplements increases power and muscle mass.

It is most often part of a pre-workout supplement and does not cause side effects. However, some mild side effects such as water retention, bloating, weight gain, and digestive problems have been noticed.

By ensuring proper dosage, you can reduce any adverse symptoms. While taking creatine, it may be hard to avoid a moderate weight gain of 4 to 6 pounds because of the increased water retention in your muscles (14, 15, 16).

Other Ingredients

Several pre-workout supplement formulas may cause adverse effects, such as stomach upset. These include sodium bicarbonate, magnesium, creatine, and caffeine.

Magnesium, as magnesium citrate, may have laxative effects. Taking too much can, therefore, lead to diarrhea.

Mixing your pre-workout supplements with less water may also upset your stomach.

A liquid that is too concentrated may lead to diarrhea. You can minimize side effects by mixing your pre-workout supplement with at least 8–12 ounces of water (17, 18, 19).


If you are taking pre-workout supplements, you may experience side effects including headaches, skin conditions, tingling, and an upset stomach.

By decreasing your dosage or avoiding supplements with specific ingredients, you can minimize many of these side effects.

Always start taking pre-workout supplements if you have trained for at least six months.

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