Pre-Workout Side Effects (Do You Really Need it)

By Ire | Supplement Review

Apr 04

Ever walked into GNC and been offered a shiny-tub by a semi-do-you-even-lift underage guy, claiming that it will change your life? While he is talking about how pumped, excited and killer workouts you will have, he forgets to mention all the possible headaches, cramp or liquid poops that it might cause.

In this article we will discuss whether pre-workout side effects out weight its benefits. We will go through common substances found in pre-workouts and see which ones are causing what.

What is a pre-workout

Pre workouts are powdered supplements that you can get in any supplement store today. Like the name suggest, they should ideally be taken before the workout in order to increase our workout performance. Better performance equals quicker gains. Therefore, it makes sense to invest in this mysterious sweet powder, right?

Muscular guy having enough energy and strength to perform heavy farmer walks

What are pre-workouts supposed to do?

Pre-workouts enhance performance in three different ways:


By containing substances that causes our Heart Rate to increase, and therefore making us more energetic and more willing to destroy our next lifting session.


By containing substances that brings more attention (water, blood…) to our muscle tissue, we have ability to contract our muscles more effectively. Therefore, we have the ability to lift more weights or even mountains.


By containing substances like slow digesting carbohydrates that will allow to sustain energy for longer. Therefore, you will feel like you can run, swim, cycle or whatever for a longer period if not forever.

Do I really need pre-workout supplements?

Yes, there is no doubt in that. Deny that precious gift from bum-fluffed salesman in GNC and you will not be send to heavenly anabolic window paradise of gains. Instead, you will fry in hardgainer’s hell!

In all seriousness, you absolutely do not need pre-workout supplements. As a personal trainer, I always tell my clients that there better ways to achieve all three benefits stated above. Therefore, make sure to get your:

  • Sleep
  • Water
  • Quality nutritious foods
  • That D-vitamin 😉

However, I must admit to you that I actually am I pre-workout supplement user. After all that shit talk, you probably didn’t expect that, did you?

I have done my research on pre-workout supplements and I found that Legion Pulse works great with my body, as long as I take it correctly.

I understand all the negative side effects and I made a conscious decision that I am willing to do it anyway. After you will be done with this article, you can make that decision for yourself.

Pre-Workout Side Effects. Muscular guy doing tire flips as a part of his workout


Short answer is: Who the hell knows?
It is kinda like a Kinder Chocolate egg you got when you were a kid (if not, I am sorry to say but your childhood was sad). Sometimes the toy was completely awesome and other times it was 4 fucking puzzle pieces.

Pre-workout supplements are really not well regulated. Since it is not a drug, there really aren’t too many rules controlling supplement companies.

“Federal law does not require dietary supplements to be proven safe to FDA’s satisfaction before they are marketed. “

However, there is a common thread of substances that are usually advertised to be within your pre-workouts. I will got through each of them and explain their side effects seperately.


Below I list all most common substances used in pre-workout supplements and their possible side effects. Pre-workouts are supposed to give your workout more energy, strength and endurance.

Supplement companies try to promote recovery as well, however it seems kind of controversial to add anabolic ingredients into catabolic product? Some of the supplements even contain substances which help with focus.

In order to make products sweet and shiny, most of supplements have also added sugars (artificials or sugar alcohol) and coloring.


1. Caffeine

I think we all know that one. It is the most popular ingredient used to keep Westenized world running. It stimulated our CNS (Central nervous system) which prevents you from getting tired.

  • Common side effects: anxiety, insomnia, digestive issue, high blood pressure

2. Yohimbe

It is a substances that has also been used to reverse sedation in dogs. Substance which is made out of bark of an African tree, is known to dilate our blood vessels (even the ones in your pants) and irritate CNS. The research on Yohimbe has quite poor.

  • Common side effects: Gastrointestinal distress, increased heart rate, anxiety, high blood pressure, heart attack, seizure


DMAA or Methylhexanamine is an actual drug which was used by original Pre-workout supplement Jack3D and many other energy drink companies. After proven causes of 5 deaths, the substances was banned by many sport authorities. However, there are still companies out there (2019), which sell supplements that contain DMAA. BEWARE WHERE YOU GET YOUR PRE-WORKOUTS FROM!

  • Common side effects: doesnt matter because of DEATH


It is an amino-acid group consisting of leucine, isoleucine, valine and proteinogenic amino acids. Together they acts an energy source when taken before workout. Many supplements just add leucine in their pre-workouts which does just as much work as nipples do on a male.

  • Common side effects: fatigue, loss of coordination, nausea, headache, increased insulin resistance


1. Creatine

Creatine is a fantastic substance for increasing strength. Due to the fact that is draws water toward muscle cells it allows your muscle to perform on a higher level. While that is not the best news for some other organs (liver: help, I am dehydrated), your workouts will be more effective. That is why it is suggested, to drink plenty of water when taking creatine.

  • Common side effects: Kidney damage, bloating, dehydration, muscle cramps, digestive problems

2. Beta Alenine

Amino acid which increases exercise and cognitive performance. It is also found in meat, fish and some poultry. Commonly, we experience paraesthesia with it. That is a tingling (itching sensation).

  • Common side effects: Tingling sensation


1. Citrulline Malate

Citrulline malate is an amino acid usually found in fruits. It raises nitric oxide and blood flow which increases muscle pump. It helps aerobic energy production. Therefore it will help you exercise more effectively for longer period.

  • Common side effects: High blood pressure, heart disease, mild moderate erectile dysfunction

2. Arginine

Another amine acid which is naturally produced by the body. It also raises nitric oxide, however there is no real evidence that arginine supplementation helps with performance.

  • Common side effects: Bloating, abdominal pain, diarrhea, low blood pressure, airway inflammation

3. Glutamine

Yet another amino acid that your body can produce naturally. However, due to common lack of production, supplementation in theory should help with increasing muscle mass and decreasing muscle degradation. However, current studies has shown that glutamine supplementation only assists extreme endurance athletes with recovery. Therefore, if you are not preparing for a marathon, adding glutamin in your pre-workout will be unneccesary.

  • Common side effects: Not enough evidence


1. Vitamin B6, B12

Vitamin found in fish, nuts, milk and meat. Helps with converting food into energy. It reduces inflammation and regulates sleep. Therefore, vitamin B6 and B12 should help you with recovery. However, putting it in a pre-workout is a little controversial.

  • Common side effects: High blood pressure, dizziness, headache, rash, skin discoloratin, cold symptoms


1. Taurine

Essential substance for cardiovascular function and skeletal muscle function. It is known to increase focus and is therefore often found in energy drinks.

  • Common side effects: Not recommended for people with kidney problems, increased heart rate

2. Tyrosine

Another amino acid which is used to improve alertness. It does that by helping with realeasing of dopamine, thyroid hormons and adrenaline.

  • Common side effects: No side effects unless mixed with medication


1.Red 40

  • Common side effects: Hyperactivity, could be carcinogen

2. Blue 1

  • Common side effects: Hyperactivity


1. Acesulfme potassium

  • Common side effects: carcinogen

2. Splenda (sucralose)

  • Common side effects: irritable bowel syndrome


1. Erthritol

  • Common side effects: Cramps, nausea, flatulence, diarrhea

2. Glycerin

  • Common side effects: Diarrhea, nausea, vomiting, headache

3. Inositol

  • Common side effects: Diarrhea, dizziness, flushing, nausea, vomiting, upset stomach, itching

4. Polydextrose

  • Common side effects: Bloating, excessive gas, cramping, abdominal pain

5. Xylitol

  • Common side effects: Gas, bloating, diarrhea
Muscular guy with a beard posing with a shirt that says: Work harder


Earlier we talked about how nobody really knows what is in your pre workout supplements, since supplements are not regulated by FDA (Food and Drug Administration).

Then we went into details on substances that are known to be included and even those show to have some horrible side effects. Hell, DMAA caused death??

So what do you do? How can investing in pre-workout be a smart idea? Well, it really isn’t.

  • If you want to play a safest game, prioritize all natural ways to increase energy and never even consider taking magic powdered scoop.
  • Second option is to pick one substance that fits and buy a supplement with only that substance in it. For example, Nutricost Caffeine Pills only contain caffeine. That will not only eliminate risk of having side-effects of other products but also a risk of having side effects by mixing different substances.
  • Invest in a well researched and proven Pre-workout supplements. If you are going to be as stupid as I am and ignore the two steps before, at least make sure that your supplement is well rated by third-party companies. I use Legion Pulse Pre-workout because it has received best possible ratings on Labdoor (a two third-party company evaluating how clean and legit the product is).

It wouldn’t be fair to not acknowledge that even proved healthy supplements like vitamin-C causes side effect. In fact, pretty much everything you can think about will cause some kind of negative side effects. No matter, if that is healthy or unhealthy ingredient. Vitamin-C which is commonly recommended by dietitians and doctors can cause: Redness, headache, upset stomach, nausea , fainting… So keep that in mind.

How much caffeine is too much caffeine?

So, lets just limit it down to caffeine instead of the whole mix of substances. How much caffeine should you really be taking?

-Average cup of coffee: 95mg
-Starbucks Grande (16 fl oz): 165mg
-Dunking Donuts Medium (24 fl oz): 297mg
-Tim Hortons Large (20 fl oz): 205mg
-Red Bull (20 fl oz): 189mg
Nutricost Caffeine Pills: 100mg per capsule

For athletics performance, they recommend for caffeine to not exceed 3mg per kg (lbs/2.2) of bodyweight. Meaning if you weigh 220 lbs (100kg) you should maximally be consuming 300mg of caffeine. Anything more than that will increase the likely-hood of side effects.

Guy doing sit ups in the track and field stadium. Pre workout helps him destroy his workout. But, will he suffer from side effects after?


Can you get addicted to pre-workout? ABSOLUTELY. In fact, you can get addicted to just about anything. People are addicted to licking their cats, so being addicted to a pre-workout really isn’t that weird.

What happens is that we become less sensitive to stimulants and we therefore require more and more every training in order to get the same kick out of it. That can lead to excessive consumption and horrible side effects. That is why I recommend to stay away from pre workouts or at least cycle it when taking it. I talk more about pre-workout cycling below.

How to take pre-workout supplements?

1. Dosage

NEVER, EVER exceed recommended labeled dose. Do not fall into a trap of just increasing your intake until your heart explodes during a set of Deadlifts (maybe little exaggerated)

2. Timing

It will usually take from 20-30 minutes in order to kick in and another 30 minutes to peak. Select the timing in order to peak for your compound exercises.

3. Cycling

Some people will say this is complete bullshit, and honestly they might be right. If pre-workout has worked for them for more than 6 months with still getting same kick without needing to increase the dosage, they have a point.

Human bodies are different and we react differently to things. My recommendation is to observe how your body responds. If you feel like your energy levels are declining, cycling is a good option for you.

Taking off Legion Pulse for 2 weeks every 6 weeks works great for me.


Lots has been discussed in this article. Hopefully you are one of the smart ones and will never even think about taking a scoop of excitement.

Remember that supplements are not FDA regulated and many companies use that. Nobody really knows what is in those tubs. They are supposed to offer energy, strength and endurance, however that comes along with sugars and coloring. In combination, pre workout side effects are not the most pleasant. Hell, DMAA caused 5 deaths!?

I gave you list of substances that are commonly used in pre-workouts, their function and side effects. Be smart and do your research on what you are buying. Do not just trust overly-excited younker in GNC.

After all this, if you are still planning to invest in a preworkout, make sure that has been researched by third party companies. Labdoor gave Legion Pulse best rating possible.

Even though pre-workout is not a drug, it could still be dangerous to your health. Therefore, make sure to take it responsibly!

If you are a skinny guy looking to add muscle with realistic expectations, check out more on this website. I do not give you empty promises like GAIN 30-LBS OF LEAN MUSCLE IN 3 MONTHS. All I can offer is years of knowledge based on my own experience with clients and myself on how muscle building really works.

Remember to NOT to take pre workout supplements and LIFT, EAT, SLEEP, REPEAT!

About the Author

Hey, my name is Ire.I am a Personal Trainer/ Strength Coach based in Stockholm, Sweden.When you don't find me in the gym, I will most likely be on a Track and Field stadium throwing around a discus.