No clinical evidence links creatine supplementation to anger, aggression, or irritability. No peer-reviewed human trial has found that taking creatine causes mood disturbances of any kind. In fact, the available research points in the opposite direction: creatine appears to support brain energy balance and may even improve mood in some people.
Why People Associate Creatine With Anger
The belief that creatine causes anger almost certainly comes from confusion with anabolic steroids. “Roid rage,” a well-documented side effect of synthetic testosterone use, gets loosely applied to anything associated with the gym and muscle building. But creatine and steroids have completely different chemical structures, work through entirely different mechanisms, and are regulated differently under federal law.
Anabolic steroids are synthetic versions of testosterone. They enter muscle cells, bind to hormone receptors, and directly alter gene expression related to muscle growth. They also affect the brain’s hormonal environment, which is why aggression and mood swings are recognized side effects. Creatine does none of this. It’s a naturally occurring compound your body already makes from amino acids, and it works by helping cells regenerate their primary energy molecule, ATP. Steroids are Schedule III controlled substances requiring a prescription. Creatine is a dietary supplement sold alongside protein powder, with no legal restrictions on its purchase or use.
What Creatine Actually Does in Your Body
Creatine’s job is straightforward: it helps your cells recycle energy faster. When a cell burns through ATP (its fuel), creatine donates a phosphate group to rebuild that ATP so the cell can keep working. This matters most during short bursts of high-intensity effort, which is why creatine improves strength and power output in the gym.
This same process happens in the brain. Although brain creatine makes up less than 5% of the body’s total supply, it’s critical for maintaining energy balance in neurons during periods of high demand. The brain uses rapid ATP turnover constantly, for everything from processing neurotransmitters to managing calcium and sodium transport between cells. Creatine acts as what researchers describe as a “bioenergetic thermostat,” quickly replenishing ATP to keep brain cells functioning smoothly when energy demands spike.
Creatine and Hormones
One theory behind “creatine rage” involves hormones, specifically the idea that creatine raises dihydrotestosterone (DHT) or testosterone to levels that could trigger aggression. A single 2009 study on rugby players suggested creatine might increase DHT, and this finding took on a life of its own online. But it was never replicated.
A 2025 randomized controlled trial put this question to rest more directly. Over 12 weeks, researchers measured total testosterone, free testosterone, and DHT in participants taking creatine versus a placebo. There were no significant differences between the two groups for any hormone. Both groups saw testosterone rise slightly over the study period, but this happened regardless of whether they were taking creatine or not. Creatine simply doesn’t function as a hormonal agent.
Creatine’s Effect on Mood and Sleep
Rather than harming mood, creatine may actually support it. Researchers have been studying creatine as a potential add-on treatment for depression, based on the observation that people with depression often show disrupted brain energy metabolism, reduced ATP production, and mitochondrial dysfunction. Creatine’s ability to restore energy balance in brain cells, increase cellular resilience, and influence neurotransmitter systems makes it a plausible candidate for mood support. Oral creatine supplementation has been shown to increase levels of phosphocreatine in the brain, directly boosting the brain’s energy reserves.
Sleep disruption is another route that could theoretically lead to irritability. If creatine kept people awake, that alone could explain anger the next day. But a randomized, double-blind, placebo-controlled crossover trial found the opposite: a seven-day creatine loading protocol actually improved subjective sleep quality compared to placebo, with a moderately large effect size. Creatine had no effect on sleep latency (how long it takes to fall asleep), total sleep time, or sleep efficiency. It also didn’t change stress levels or emotional state scores compared to placebo.
What Might Actually Be Causing Irritability
If you started taking creatine and noticed you feel more irritable, creatine itself is unlikely the cause. But several things that often change alongside creatine use could explain it.
- Intense training: People often start creatine when they ramp up their workout intensity. Hard training elevates cortisol, disrupts recovery if overdone, and can leave you feeling short-tempered, especially if you’re not sleeping or eating enough to match the increased demands.
- Stimulant-heavy pre-workouts: Many people start creatine at the same time they begin taking pre-workout supplements loaded with caffeine and other stimulants. High caffeine intake causes anxiety, jitteriness, and irritability in a dose-dependent way.
- Caloric restriction: Creatine is popular during both bulking and cutting phases. If you’re in a calorie deficit, low blood sugar and reduced energy availability can make anyone more prone to frustration and mood swings.
- Expectation effects: If you believe creatine is “like steroids” and expect it to make you more aggressive, that belief can shape how you interpret normal fluctuations in mood.
Safety Profile at Standard Doses
The International Society of Sports Nutrition has reviewed the safety and efficacy of creatine supplementation extensively, covering its effects on performance, recovery, injury prevention, neuroprotection, aging, and clinical populations. No psychological or behavioral side effects, including anger or aggression, appear in the documented safety profile. Creatine monohydrate at standard doses (3 to 5 grams per day for maintenance, or 20 grams per day during a short loading phase) is one of the most thoroughly studied supplements in sports nutrition, with decades of research and no established link to mood disturbance.
The bottom line is simple: creatine is not a hormone, does not alter your hormonal profile, does not disrupt sleep, and does not act on any neurological pathway associated with aggression. If anything, its role in brain energy metabolism and emerging research in mood disorders suggest it leans in the opposite direction.