While creatine is considered a safe and well-researched supplement, it does come with potential side effects. When taking more than the recommended 3 to 5 grams a day—such as during the loading phase—you may experience stomach upset, water retention, and slight weight gain. With prolonged use at high levels, you could also experience muscle cramps, electrolyte imbalances, kidney issues, and elevated liver enzymes.
Taking higher doses of creatine may cause digestive upset. Researchers have found that taking about 10 grams per day may trigger gastrointestinal (GI) symptoms like stomach upset, diarrhea, bloating, and nausea.
This side effect is less likely to occur with standard doses. If you are taking higher doses of creatine and have digestive issues, try reducing the amount you take.
Taking higher doses of creatine during a loading phase, or about 20 grams a day for five to seven days, may cause you to retain water. Typically, this water weight is temporary and will go away after you begin the maintenance phase of 3 to 5 grams daily.
If you want to avoid water retention, stick to the recommended dose of 3 to 5 grams per day and skip a loading phase. You will still experience positive results—just not as quickly.
It is not uncommon to gain a little weight when taking creatine. Some of this weight gain is temporary and related to water retention. Your weight may increase by two to six pounds during a loading phase. This weight gain is usually temporary and will go away once you switch to a maintenance dose.
You may also gain a small amount of weight due to an increase in muscle mass. This muscle weight gain improves your body composition and helps with fat loss, and should not be a cause for concern.
Because creatine is filtered through your kidneys, there is a risk of kidney issues, especially if you have existing kidney conditions. If you do have pre-existing kidney disease, do not supplement with creatine without talking with a healthcare provider.
If you have normal kidney function, you can likely use creatine without any issues. The rise in creatinine levels is usually only temporary, but it can still be helpful to talk with a healthcare provider.
Some research has found that supplementing with creatine can reduce the risk of muscle injuries. However, other studies have found that creatine supplementation may lead to increased muscle cramping or muscle strains.
The key to reducing these risks is to stay hydrated, pay attention to your body, and make adjustments. Some muscle cramping may be caused by overuse or a lack of water.
Creatine causes water retention and pulls water away from the rest of your body. If you do not stay well hydrated while supplementing with creatine, this may cause an electrolyte imbalance. Monitor your water intake, especially if you live in a hot climate or you frequently do high-intensity exercises.
Although rare, there have been some reports of elevated liver enzymes from taking creatine. If you are taking another medication or supplement metabolized by your liver, or if you have an existing liver condition, talk to a healthcare provider before supplementing with creatine.
