Doctor issues warning to anyone taking pre-workout supplements

From a daily creatine to post-gym protein shake, plenty of you gym rats will have a pretty dedicated routine when it comes to working out.

And that’s just in the supplements, let alone the actual gym routine.

For many, the session doesn’t even start until you’ve had your pre-workout, typically being some kind of concocted drink that’s high in caffeine.

Just like creatine has, pre-workout has surged in popularity from elite sport to the mainstream over recent years. But as there is with most things, there can be a number of side effects to using these supplements.

And a doctor recently took to YouTube Shorts to issue a bit of warning about using caffeine – particularly in ‘powdered forms’.

While his videos do not serve as a substitute for professional medical advice, Dr Sermed Mezher is a published academic author who shares ‘high quality scientific content’.

Pre-workouts can have a number of side effects. (Getty Stock Image)

The doc’s warning

“It’s very hard to get too much caffeine from coffee, but powdered forms are a whole other animal,” he said in one video.

Dr Mezher claimed many pre-workouts are now ‘containing these powdered forms of caffeine’ and that there’s a misconception that: “The more you have, the better you’ll perform.”

However, he says this absolutely isn’t ‘always the case’.

Instead, he claims there is the ‘potential’ that they can cause: “Fast heart rate, tremors, hallucinations, and even seizures.”

Dr Mehzer added: “To get that much caffeine from coffee, even if you were taking double espressos, you’re looking at about eight cups to reach over a gram.

“But if you’re looking at powdered forms, it’s simply just a few scoops.”

So, while he says ‘take your pre-workouts’, it’s important to ‘do so responsibly’.

You'd need a lot of coffee to get the same effect. (Getty Stock Image)

Benefits of pre-workout

There’s no denying that a pre-workout can help get you through a particularly strenuous session at the gym – especially if you’re someone who hits it first thing in the morning or after a long, tiring day.

And registered sports nutritionist Rob Hobson told Men’s Health: “For me, the main performance benefits come from ingredients like caffeine, which is well-researched for improving alertness and endurance, and carbohydrates, which provide the fuel your muscles actually need.”

Generally, pre-workout has the ability to optimise your strength, improve your endurance and focus and help to build up more energy during training.

FSA warning

In 2024, the Food Standards Agency (FSA) issued guidance on food supplements containing caffeine.

“As caffeine is rapidly absorbed into the bloodstream, stimulatory effects may begin 15 to 30 minutes after ingestion and may last for a number of hours exerting physiological effects or leading to side effects (for example headaches and nausea),” it explained.

The agency said that caffeine intakes of up to 400mg per day are unlikely to cause adverse effects for most individuals.

It warned: “High levels of caffeine can cause anxiety, sleeplessness, agitation, palpitations, diarrhoea and restlessness, and individuals with a mental health condition can experience worsened psychosis. These effects may be more severe in individuals who are caffeine sensitive and/or have underlying health issues such as heart disease or high blood pressure, and effects may occur at lower doses.”

The FSA added that excessive consumption is associated with various serious adverse effects: “Such rapid heart rate, abnormal heart rhythms and seizures, which have been observed at intakes of approximately 1.2 grams (1,200 mg) of caffeine. Caffeine intakes of above 10-14 grams (10,000-10,400 mg) have been reported to be fatal, although smaller doses can also be life-threatening to sensitive populations. These cases have occurred where pure caffeine has been measured incorrectly.”

So, make sure to read the label properly and calculate in your other sources of caffeine such as tea, coffee and energy drinks.