Creatine Supplements: What You Need to Know & When to Tell Your Doctor
By Dr Timothy Eden, MBBS, RD from Eden Health and Nutrition
Read time approx. 4mins
Why Is Everyone Talking About Creatine?
Creatine supplements have rapidly grown in popularity in recent years, frequently promoted by personal trainers, fitness enthusiasts and nutrition influencers across social media. Once a product mainly found in the gym bags of bodybuilders and athletes it’s now commonly used by everyday gym goers and those looking to maintain muscle mass with age. This shift reflects a broader cultural move towards health and fitness among younger and more diverse groups. While creatine is often marketed as a “pre-workout” supplement, its benefits extend beyond this with increasing evidence supporting its role in enhancing exercise performance and supporting muscle maintenance particularly when paired with adequate protein intake and resistance training.
But is it safe? Who should be cautious? And why might it be important to mention to your doctor? Let’s take a closer look.
What Is Creatine and How Does It Work?
Creatine is a naturally occurring compound found in muscle cells. It helps your muscles produce energy during high-intensity, short-duration activities such as weightlifting or sprinting. Most of our creatine is stored in muscles but we also obtain small amounts from foods like red meat and fish.
Supplementation typically uses creatine monohydrate, which has been widely researched and shown to:
Improve strength and muscle mass during resistance training
Enhance recovery between workouts
Increase training volume and output
A systematic review published in Journal of the International Society of Sports Nutrition (2017) confirmed that creatine monohydrate is one of the most effective and safest supplements for increasing lean body mass and high-intensity exercise performance.
How Much Should You Take and When?
The most common dosing strategies are:
Loading phase: 20g/day split into 4 doses for 5–7 days (mainly used by athletes or individuals in performance fitness/sport)
Maintenance phase: 3–5g/day thereafter
However, you can skip the loading phase and simply start with 3–5g/day which is effective but takes a little longer to achieve the same muscle saturation but more sustainable for your common gym goer which will still help achieve results!
Should You Take Creatine Before or After a Workout?
While creatine works best when taken consistently over time, there is some evidence suggesting that post-workout may be the optimal time to take it especially when consumed with a source of protein and carbohydrates. A well-cited study by Antonio & Ciccone (2013) found that participants who took creatine after resistance training saw greater improvements in muscle strength and lean body mass compared to those who took it beforehand. The proposed mechanism is that after exercise your muscles are more insulin-sensitive, which may improve creatine uptake when paired with a meal or shake. However, consistency is more important than precise timing and creatine will be effective as long as you’re taking it daily and allowing your muscles to become saturated over time.
It’s worth noting that creatine draws water into the muscle cells. This is not directly harmful but can cause a temporary increase in weight due to fluid retention; something to bear in mind if you're tracking weight changes.
How Can You Take It?
Creatine is typically available as:
Powdered form (often tasteless and easy to mix with water or a protein shake)
Capsules or tablets for convenience
Because the supplement industry is not tightly regulated, it’s essential to choose products from reputable brands that are third-party tested (look for Informed-Sport or NSF certification). This helps ensure you're getting a pure product without contaminants. For the more elite sporting types this is particularly relevant as products that are informed sport certified have been screened for substances banned in sports by the World Anti-Doping Agency (WADA).
Who Should Be Cautious with Creatine?
While creatine is generally considered safe for healthy adults, some groups should approach with more caution:
Teenagers under 18: There is limited trial data on long-term use in this group. Unless advised by a health professional, it's generally not recommended.
Older adults: While some evidence supports creatine use in older populations for preventing sarcopenia (muscle loss), individual health status must be considered especially renal function.
People with pre-existing kidney disease: Since creatine is broken down into creatinine, a waste product cleared by the kidneys there is concern it could worsen kidney function in those already compromised; though evidence is still mixed.
Should You Tell Your Doctor You’re Taking It?
Yes; especially if you're having a blood test that includes kidney function.
Creatine supplementation increases your body's creatinine levels. Creatinine is one of the main blood markers used to assess kidney health (eGFR), so if you've recently taken creatine, it can falsely elevate this reading, potentially leading to:
Misinterpretation of renal function
Unnecessary repeat testing or referrals
I have seen many patients in clinic who have seen a dramatic decline in their kidney function and on closer inspection this is due to their recent dietary intake of supplements. So please follow below to ensure the more accurate results for your healthcare professional!
Top tip: So if you’re having a blood test (especially for NHS health checks or chronic disease monitoring), consider a short washout period of 7–10 days beforehand. Also, let your GP or the nurse requesting your blood test know about your supplement use so they can document it.
Final Thoughts
Creatine it would appear has earned its place in the supplement world with a strong body of evidence supporting its benefits for performance and muscle maintenance. It’s safe for most healthy adults when taken as directed but not completely without caveats.
If you’re considering using creatine:
Stick to recommended doses from reputable sources
Use caution if you have underlying kidney issues or are under 18
Let your doctor know before any blood tests involving renal function
Ultimately like any supplement, creatine should complement NOT replace a well-rounded diet and exercise plan. Always take an informed approach and seek professional advice if unsure.
References:
Kreider RB et al. Journal of the International Society of Sports Nutrition, 2017. “International Society of Sports Nutrition Position Stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine.”
Rawson ES, Venezia AC. Aging and Disease, 2011. “Use of creatine in the elderly and evidence for effects on cognitive function in young and old.”
British Dietetic Association (BDA). https://www.bda.uk.com