Creatine does not have a direct, established link to anger or aggression. No clinical study has identified irritability or mood disturbances as a side effect of creatine monohydrate, and the International Society of Sports Nutrition lists weight gain as the only clinically significant side effect in the research literature. That said, a few indirect pathways could explain why some people feel more irritable after starting creatine, and they’re worth understanding.
What the Research Says About Creatine and Mood
Creatine’s primary job is buffering energy in tissues with high, fluctuating demands, especially muscles and the brain. Once it crosses into the brain, it helps shuttle energy to neurons and plays a role in learning, memory, attention, and possibly emotion. This brain-energy connection has actually led researchers to study creatine as a potential treatment for mood and anxiety disorders, not as a cause of them. Early findings suggest it may function as an adjunct to medication for conditions linked to impaired brain energy metabolism, including depression.
In other words, the biochemistry of creatine points more toward mood support than mood disruption. But biochemistry isn’t the whole picture, and a few other factors deserve attention.
The DHT Question
One commonly cited concern involves hormones. A study of college-aged rugby players found that after seven days of creatine loading, levels of DHT (a potent form of testosterone) increased by 56%, then remained about 40% above baseline during a two-week maintenance phase. The ratio of DHT to testosterone also rose by 36% during loading and stayed 22% elevated afterward. Creatine appeared to increase the rate at which testosterone converts into DHT.
DHT is more biologically active than testosterone, and high androgen levels are loosely associated with aggression in popular culture. But this connection is far weaker than most people assume. The rugby study measured hormone levels in blood, not behavioral outcomes like irritability or anger. And crucially, the study has never been replicated. Total testosterone levels didn’t change at all. One unreplicated hormonal finding doesn’t establish a mechanism for anger, but it’s the closest thing the research offers to a biological explanation, and it’s why the idea persists online.
What’s More Likely Causing the Irritability
If you started feeling more irritable around the same time you started creatine, the more probable culprit is something else in your routine. A few common scenarios:
Pre-workout supplements. Many people begin taking creatine alongside a pre-workout powder, and most pre-workouts contain high doses of caffeine, often 200 to 400 mg per serving. Caffeine sensitivity directly affects the central nervous system and can cause anxiety, jitters, insomnia, and irritability. If you’re stacking creatine with a stimulant-heavy pre-workout, the caffeine is a far more likely explanation for mood changes than the creatine itself.
Sleep disruption. Intense training programs, late-evening workouts, or stimulant use can all cut into sleep quality. Even mild sleep deprivation makes people shorter-tempered. Interestingly, one study found that creatine supplementation actually increased total sleep duration on resistance training days in women, which would work against irritability rather than toward it.
Training intensity. People typically start creatine when they’re pushing harder in the gym. Heavier training loads, caloric deficits, and physical fatigue all affect mood independently. It’s easy to attribute a mood shift to the new supplement when the new training stimulus is the real variable.
Not drinking enough water. Creatine pulls water into muscle cells. If you don’t increase your fluid intake to match, even mild dehydration can leave you feeling foggy, fatigued, and irritable. This is one of the most common and most easily fixed issues with creatine use.
People With Pre-Existing Mood Conditions
Because creatine plays a genuine role in brain energy metabolism, people with psychiatric conditions involving disrupted energy pathways, such as bipolar disorder or schizophrenia, occupy a more complicated space. Creatine’s influence on brain energy could theoretically interact with these conditions in unpredictable ways. The research exploring creatine’s relationship to psychiatric disorders is still early, and our understanding of how it affects emotional processing at the neurological level remains limited. If you have a diagnosed mood disorder and notice emotional changes after starting creatine, that’s worth discussing with whoever manages your care.
The Safety Profile Overall
Creatine monohydrate is one of the most studied supplements in sports nutrition. The ISSN’s position is that it is safe, effective, and ethical when taken within recommended guidelines, and that no scientific evidence shows detrimental effects in healthy individuals from short- or long-term use. Anecdotal claims about side effects like cramping and dehydration persist in popular media, but controlled studies have not validated them. Anger and aggression don’t appear anywhere in the clinical side-effect literature.
If you’re experiencing noticeable irritability, the most productive approach is to isolate variables. Try dropping any stimulant-based pre-workout for a week while keeping creatine. Make sure you’re drinking enough water. Track your sleep. In most cases, the anger has a simpler explanation than the creatine itself.