Can You Take Pre-Workout Twice a Day? (Is It Safe or Risky?)

Benedict Ang, CPT, PN1-NC
Published by Benedict Ang, CPT, PN1-NC | Staff Writer & Senior Coach
Last updated: November 24, 2023
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A recent client hired me to prep him for some special forces drill, and I designed a program that included two workouts a day.

After a week of training, he asked me if he could take a pre-workout for both sessions on a daily basis to help keep his motivation high.

Even though I told him taking a pre-workout twice a day was a bad idea, to drive the point home, I spent a few days going through relevant studies with my dietitian and discussing the results.

These are our insights.

Quick Summary

  • You should not take pre-workout supplements twice a day to avoid side effects from caffeine overdose.
  • Consuming too much caffeine can cause nervous system issues, interfering with fat oxidation, insomnia, anxiety, or nausea.
  • Most pre-workout supplements contain caffeine close to the FDA recommended daily limit of 400 mg.
  • I've had clients obsessed with gains fall into the trap of upping their pre-workout dose, leading to tolerance and dependency.

Can you Take Pre-Workout Twice a Day?

Getting a scoop of pre-workout supplement

It’s not ok to take pre-workout twice a day unless you’re using stim-free varieties since excessive stimulant intake can cause certain health risks.

However, most pre-workout supplements contain caffeine as a primary stimulant in doses close to the limit stated by the FDA, which is 400 mg daily [1].

While these amounts may help you get most of your training session, research conducted by the National Academy of Sciences indicates that the caffeine half-life is approximately five hours (varies from 1.5 to 9.5 hours). [2].

Half-life is the time your system needs to clear half of the given substance from your bloodstream.

“The half-life of the drug typically is around four to five hours, but it can range dramatically from as quickly as an hour and a half to as much as nine hours, depending on genetic factors and coadministration with other medications, including oral contraceptives, and smoking.”

- Stephen Devries, MD & Preventive cardiologist 

That’s why consuming excessive pre-workout supplements, like twice a day, will probably make you exceed optimal caffeine intake and accumulate it in your system.

This accumulation can result in higher tolerance, as caffeine is technically still a drug.

In my experience, two scoops quickly become two and a half, and then all the way to not feeling the impact at all.

This way, you might be simultaneously impairing your mental performance and creating sleep issues.

This creates a vicious circle - the more you consume it, the more you need it to provoke the same effects, paving the way to unhealthy addiction.

It can get even worse if you regularly consume caffeine from other sources (like drinking coffee before a workout, coke, or energy drinks) on the same day, which many people do.

Let’s get into the potential negative effects of pre-workout in more detail.

Downsides of Taking Pre-Workout Twice a Day

Taking a pre workout drink

Downsides of taking pre-workout twice a day may include hormonal disbalance, nutrient absorption issues, caffeine-induced side effects, and faster development of supplement tolerance.

Caffeine-induced side effects like nausea, insomnia, jitters, anxiety, headaches, and fast heart rate are common if too much caffeine is consumed [3].

Too much caffeine, in the long run, can also interfere with your hormones and chronically keep your cortisol levels high.

It could mess up your fat cell metabolism (lowering the fat-burning potential) and trigger memory issues or depression, based on research published by Psychosomatic Medicine [4].

“It would be incorrect and simplistic to say coffee raises cortisol, but if you’ve got caffeine in your body, it’s harder to lower cortisol levels.”

- Alan Christianson, NMD

Furthermore, caffeine modulates GABA and dopamine neurotransmitters (feel-good substances) which could cause certain mood disorders like depression according to a study published in the Saudi Pharmaceutical Journal [5].

To make things worse, excessive caffeine intake may disrupt the absorption of minerals and vitamins necessary for the production of those neurotransmitters in the first place.

Caffeine overuse might also trigger more problematic side effects, especially in women, like unstable bladder per a study published in Food Additives & Contaminants [6]. A similar problem might arise with other main pre-workout ingredients like branched-chain amino acids or creatine (non-essential amino acid).

On the other hand, many pre-workout supplements contain high doses of vitamins like vitamin B3, which can cause liver damage if taken in excess according to research from The Gale Encyclopedia of Alternative Medicine [7].

There's long term effects to consider as well, as chronic use of high caffeine products have been linked to increased cardiovascular risks.

There's also a financial downside. My favorite pre-workouts are a bit pricey, so doubling up on scoops daily would burn through my stash and really hit the wallet hard.

Possible Workarounds

Different types of pre-workout supplements

You might be able to take a pre-workout supplement twice a day if you are using an underdosed or caffeine-free pre-workout option. This way, stimulants like caffeine won’t build up in your system.

Another approach I've tried is splitting the recommended dose of some standard pre-workout supplements into two smaller doses.

However, remember that caffeine-free options won’t significantly improve your exercise performance and, consequently, muscle gain.

They will have less noticeable pre-workout effects like a slight energy boost or improved cognitive function and blood flow.


Can You Take Too Much Pre-Workout?

Yes, you can take too much pre-workout, which could cause effects like cramps, jitters, vomiting, high blood pressure, and even cardiac arrest in some cases. That’s why it’s recommended not to take more than one serving per workout and generally within 24 hours.

Why Am I Not Feeling My Pre-Workout?

You are not feeling your pre-workout either because your timing is bad (you are taking it either too early or too late) or because the dosage of certain ingredients is not high enough.


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