An Athlete resting on a gym bench thinking about the side effects of pre-workout

The 7 Potential Side Effects of Pre-Workout Supplements

If you’re someone who’s regularly using sports nutrition supplements before training, then you have probably wondered about pre-workout supplements side effects and what you can do to avoid them and be safe!

So is pre-workout good for you and is it safe?

Since these types of training enhancers are sold under the dietary supplements label – they don’t come under FDA rules. It means that their marketing claims are not regulated or scientifically approved!

This is exactly the reason why we take great care in choosing only the healthiest and safest possible supplements in our Best Pre-Workout and Best Pre-Workout for Women top ten lists! Products that are scientifically proven to be safe and provide you with consistent and real results, backed by actual clinical trials!

We know that there are hundreds of different knock-off products on the market that use sub-par and sometimes even downright dangerous or illegal ingredients while claiming miraculous and unverified results, just so that they can get your money.

We completely and utterly disagree with such practices and distance ourselves from these garbage products!

That said, even though legitimate pre-workouts are proven to be safe for healthy adults, they may still present some potential side-effects. We’re here to educate you about them!

Also, to find out everything else about this type of pre-training enhancer, check out our Complete Pre-Workout Guide: Facts, Benefits, Side Effects.

Safety Fact: Always Respect the Proper Serving Dosage

An attractive young and fit woman holding pre-workout

It goes without saying, but you should always respect what the manufacturer specifies on its label because most side effects happen due to people using a higher dosage than they should.

Too much pre-workout is a bad thing!

Most trusted and reputable manufacturers have put in a lot of work and conducted multiple clinical studies to find out which ingredients should be taken at which doses and they have this information specified on their labels for a very good reason!

That reason is maximum safety and efficiency!

The Danger of Proprietary Blends

Before we get on with the list of potential pre-workout drink side effects, I want to bring your attention to one of the biggest offenders of all when it comes to product safety.

Namely – proprietary blends!

They aren’t that big of a deal with a certain few products that contain ingredients that are proven to be side effect free, but when it comes to a pre-workout supplement that can contain upwards of 30 different ingredients – a proprietary blend can even be a very dangerous thing!

For example, imagine if a pre-workout contained a proprietary blend of stimulants! Let’s say it contained Caffeine, Synephrine, Green Tea Extract and Yohimbe, or even, god forbid, the dangerous Ephedra!

If you don’t know how much of each of those stimulants is contained in the product – you would be crazy to buy it!

Imagine if the product contained 500mg of caffeine and you wouldn’t know about it because it was hidden behind a proprietary blend. If you had a weak heart – it could even potentially stop from such an overdose!

So when it comes to pre-training additives – do yourself a favor – steer far away from proprietary blends unless they come from exceptionally reputable and trusted manufacturers. And even then, it’s not such a great idea!

The Potential Side Effects of Pre-Workout Supplements

An athletic guy pouring some water from a water bottle into his mouth

1. Dehydration

This is by far one of the most common problems, yet one of the easiest to avoid.

Since the majority of pre-exercise boosters contain quite a few diuretic ingredients, various stimulants and especially Creatine, which is proven to have a slight dehydrating effect, – it’s no wonder that a lot of people experience dehydration if they don’t drink plenty of water.

So, one of the best things you can do when taking such a supplement is making sure that you always stay well hydrated by drinking plenty of water!

2. Insomnia

Yet another common problem, especially in supplements that contain many stimulants.

If you are a person who likes to exercise during the evening, taking a pre-workout powder just before training can severely hamper your ability to sleep afterward.

In that case, you should opt for a stimulant-free before-exercise alternative instead!

3. High Blood-Pressure

Since high-intensity exercise that lasts a short duration, such as heavy weight lifting, already raise your blood pressure above normal levels, consuming large amounts of caffeine just before lifting those weights can potentially cause an even higher spike in your blood pressure, which can be problematic.

4. Diarrhea

This one usually happens due to the products having a huge number of different ingredients with them, and it all depends on each person’s ability to digest them properly. Some people’s stomachs just can’t handle it and go berserk.

5. Anxiety

The feeling of anxiety gets exacerbated by the copious amounts of various stimulants that are present in many pre-training supplements.

People who experience this should opt for stim-free options instead.

6. Jitters

Yet another downside of many stimulants, especially caffeine.

This one if the most frequently reported pre-workout powder side effects that people experience and almost everyone has felt jitters at one time or another while using pre-workouts. A stim-free option is the only choice here.

7. Kidney-Failure

It sounds like an extremely severe side effect, but it only happens if someone has kidney problems or abuses these products and takes much more than the recommended dosage.

For example, many of these sports nutrition supplements contain Creatine.

It’s a well-known fact that regularly taking much more of it than is necessary forces your body to stop its own production of this chemical and lead to an increase in production of renal by-products such as creatinine – which is safe in small doses, but in high ones can wreak havoc on your kidneys.

So again, never exceed the recommended dosage!

These are the most relevant side effects, but there are a few more. Here’s a short list:

• headaches, weight gain, nausea and dizziness, stomach problems, cramps, uncontrolled muscle spasms or movements and nervousness.

So is taking a pre-workout such a bad thing? Well, not for healthy adults! And now that we’ve talked about the dangers, you can check the following article out for the benefits of pre-exercise products: What Does a Pre-Workout Do: The 5 Main Benefits of Taking It.


Keep in mind that one of the biggest potential risks associated with various pre-workout supplements is the inclusion of dangerous substances. So we repeat this once again – never buy shady products from unknown or untrusted manufacturers and brands!

One of our biggest goals is to ensure the safety and good health of our readers – that’s why we can’t in good conscience recommend any products that have questionable ingredients or manufacturing processes.

So hopefully we haven’t completely scared you off such supplements. If not, then check out why you should consider getting one at What is a Pre-Workout Supplement and 4 Reasons to Take It.

So, what do you think about the potentially harmful effects of these types of supplements? Have you had the misfortune of experiencing one of them or had the fortune to avoid all of them altogether? Please tell us your experiences down in the comments below!

Stay healthy and safe!