Creatine has become a popular supplement in the competitive sports and fitness communities. Some people believe that it can help build up muscle and boost athletic ability. But how does this supplement affect the body, and is it really safe?

For Starters: What Is Creatine?

Creatine is a chemical that’s naturally found in meat and fish. Your body also makes creatine from amino acids in the liver and kidneys, and stores it in your muscles. There, it works as a source of energy and helps growth.

Your body uses about 1.5 to 2 grams of creatine daily. This is then replaced by whatever creatine you get from food and what is made in your body.

Researchers believe that creatine has a major role in a chemical reaction that produces the energy that muscles need to perform short bursts of physical activity.

How Is It Used?

The creatine you can buy in supplement form is synthetic. It comes in powdered form and is taken by mouth. A typical, and adequate, dose of creatine is 2 to 5 grams per day — about half a teaspoon — says Dan DeFigio, certified sports nutrition counselor in Nashville, Tennessee. You can mix that into a beverage, or simply eat it off the spoon and wash it down with a swig of water.

Some athletes use a “loading period” where they take larger doses for two to five days in order to build up the substance in their system. This method is commonly used before a competition to help performance.

Why Do People Use It?

Athletes use creatine to boost their performance during activities that require power and strength, such as bodybuilding and sprinting.

Joey Gochnour, registered dietitian nutritionist, exercise physiologist, certified personal trainer in Austin, Texas, and owner of Nutrition and Fitness Professional, explains that “creatine is used to increase your muscle’s ability for endurance during short-term exercise.”

“This means it should help you last longer during sprints, which are limited by your muscle's ability to buffer lactic acid,” he says. “It should also help you last longer, supposedly, in weight lifting for low to moderate repetitions (eight to 12) by allowing you to do more repetitions.”

“Bodybuilders like creatine because it brings fullness to the muscle. It is not about strength or performance with bodybuilding,” says Gochnour. “It’s about looks.”

Does It Work?

According to Mayo Clinic, there is evidence to show that creatine can help increase muscle mass and strength, as well as the body’s overall work ability. However, more research is needed on specific sports and activities.

Gochnour says he doesn’t personally use creatine because he’s a “nonresponder,” meaning the supplement doesn’t have performance-enhancing effects for him.

“I would recommend creatine to a serious bodybuilder, football player, or other mass-based athlete,” he says. DeFigio also recommends creatine for strength and power athletes: “It is effective, safe, and inexpensive.”

“I would not recommend it to someone who is in athletics that has to move their body through space in time for agility,” advises Gochnour, namely gymnastics, swimming, and most team sports. “I would also not recommend it for wrestling — it could increase their mass, and not their strength.”

“Additionally, I would not recommend it to anyone who could possibly get drug tested and penalized for having a positive drug test, as supplements are not the most well-regulated industry,” adds Gochnour.

Is It Safe?

Like any dietary supplement or medication, creatine has potential risks. Most studies have looked at just the short-term effects, so not as much is known about the long-term effects of using the supplement.

Common side effects include:

  • upset stomach or abdominal pain
  • diarrhea
  • muscle cramps
  • weight gain

Stop taking creatine and seek medical attention if you experience any of these serious side effects:

  • allergic reaction, especially hives, swelling, or trouble breathing
  • fast heartbeat
  • feeling dehydrated
  • seizures or fainting
  • any signs of dizziness, drowsiness, weakness, or confusion

Creatine can cause kidney damage when taken in high doses. It can also react negatively with caffeine and certain medications. If you’re taking other supplements or medications, talk to your doctor or pharmacist before adding creatine to the mix.

In addition, dietary supplements are not regulated or evaluated by the Food and Drug Administration (FDA). Creatine, like any supplement, has the potential to be contaminated with other substances that may be dangerous. Make sure you’re buying from a reliable source. Gochnour recommends looking for third-party certifications from NSF, ConsumerLab, or U.S. Pharmacopeial Convention (USP). “Supplement companies must pay these certification bodies in order to verify that they have good manufacturing practice,” he says.

Are There Alternatives?

Gonchnour says creatine is a supplement with specific properties that’s taken for a specific purpose — to increase muscle mass and short-term exercise performance — so there aren’t really alternatives that do exactly that. “Beta alanine, an amino acid, may also do similar things, but is less researched and has a side effect of a tingling sensation,” he explains.