What It Is, What It Does, and Its Side Effects

IF YOU’VE ever set foot in a supplement store (or poke around online supplement clearing houses), you’ve probably had an employee (or pop-up ad) try to up-sell you on creatine.

And that sell is strong: Creatine has been scientifically proven to enhance your strength, which can lead to muscle growth. All you have to do is pop some pills or stir some powder into your usual protein shake and it’s ready, set, swole.

But that’s just what’s advertised. Those promises of big strength and muscle gains can’t actually be true, right? And didn’t your high school buddy once tell you that taking creatine would cause your kidneys to fall out? There have got to be side effects, right?

Your skepticism is warranted. Nobody should put anything into their body without weighing the benefits and risks (and, yes, creatine does carry a few side effects that you should be aware of). It’s good to have questions about creatine.

To help you out, we turned to some of the smartest minds in nutrition to answer all of your questions about creatine supplementation.

The good news is that creatine supplementation is well-studied in scientific circles (perhaps more so than any other supplement, short of protein power). And, if you’re taking creatine supplements correctly, that science largely considers creatine safe and effective. In short, creatine, when taken as recommended, delivers on its promises of strength and muscle gain.

But them there’s the not-so-great news: You can incorrectly take creatine (read: “user error”), which can result in side effects. Take creatine the wrong way and you won’t experience the same benefits as someone who follows direction. In other words, you’re wasting your money. (And, if you’re buying the good stuff, creatine supplements aren’t cheap.)

So before you go all-in on taking creatine, here’s what the supplement actually is, what it does, and how to avoid any of its side effects.

What is creatine?

Creatine is an endogenous amino acid derivative produced by vertebrate animals and occurring primarily in muscle cells, according to the National Institutes of Health.

Basically it’s an acid that your body can produce, by way of your kidneys and liver, after you eat protein. Animal proteins, particularly red meat and fish, contain creatine naturally, but you’d need to eat almost inhuman amounts of each to hit the level available in most creatine supplements.

So how does this fit into strength and muscle growth?

Your muscles then convert creatine into creatine phosphate, which is then generated into adenosine triphosphate (ATC), which your body uses for explosive exercise.

But you’d have to eat pounds upon pounds of protein in order to get the amount of creatine you need to produce a benefit. Supplement manufacturers have made creatine intake more efficient. Instead of packing in a tower of T-bones, all you have to do is take the nutrient in powdered, liquid, or pill form.

Also important: Creatine supplementation should be considered complementary to consuming protein, not a replacement for. That’s because creatine and protein work in different ways. In short, creatine leads to more strength during your workout while protein leads to more muscle repair after your workout.

What are the effects of taking creatine?

You get stronger—but not immediately.

Creatine increases the body’s ability to produce energy rapidly. Creatine exists naturally in your body and helps fuel your muscles, which is why some people take it as a supplement to boost their performance in the gym.

The mechanism is straightforward: If you’re able to lift more weight in the gym, you’re able to create more of the muscle fiber tears that your body can then repair and rebuild bigger and stronger after your workout.

According to the U.S. National Library of Medicine’s MedlinePlus, creatine is rated as “possibly effective” when it comes to improving muscle strength.

“There is a lot of mixed research on creatine’s ability to improve muscle strength,” the government website says. “However, analyses of this research show that creatine seems to modestly improve upper body strength and lower body strength in both younger and older adults.” Creatine has also been shown to improve athletes’ performance in rowing, soccer, and jumping height.

Don’t worry, though: “You should feel good about your creatine supplementation,” Men’s Health nutrition advisor Michael Roussell, Ph.D., says. “Take 5 grams of creatine monohydrate with your workout shake to help you get bigger and stronger.”

Although some research has pointed to creatine’s efficacy for high-intensity, explosive exercises like sprinting, the overall results have been mixed.

What are the short-term effects of creatine?

One thing is almost certain: If you take creatine, you’ll gain weight.

“Creatine is a quick way to add muscle, but not without some water weight, too,” Carolyn Brown, R.D., a nutrition counselor at Foodtrainers. “Most people gain between two and four pounds of water retention in the first week.”

But that water weight is good, Roussell points out: “Creatine’s going to pull more water into your muscles, making your muscles bigger and fuller.”

And if you’re not gaining weight on creatine in the short-term, you may not be drinking enough water. Make sure you’re well-hydrated when you’re taking creatine supplements.

What are the long-term effects of creatine?

After that initial retention period, subsequent gains are due to the increase in the workload you can handle, according to Paul Greenhaff, Ph.D., professor of muscle metabolism at the University of Nottingham in England.

Basically, if you continue pushing harder and harder in the gym, creatine will keep fueling you to greater gains.

Some people think that if they take creatine and don’t work out, they’ll put on fat—but Roussell says it isn’t true.

“Creatine contains no calories, and has no impact on your fat metabolism,” he says. “So taking creatine and not working out is just going to lead to nothing.”

That said, you can’t take creatine, not workout, and expect to gain muscle. It just doesn’t work that way.

What are the best forms of creatine?

Some forms of the supplement are indeed better than others.

“If you’re going to add a supplement in, make sure it’s creatine monohydrate,” Brown says. “A lot of other supplements out there will have a lot of junk that you don’t need, and they’ll be much more expensive.”

One category to watch out for: “pre-workout” supplements that advertise that they contain creatine. Surprise: Many of these supplements do not contain the minimum amount of the nutrient proven to be effective.

Powder is the way to go. Studies show that liquid creatine and creatine ethyl ester (CEE) are unstable and break down in your blood system. Don’t bother with them.

Chad Kerksick, Ph.D., assistant professor of exercise physiology at the University of Oklahoma, recommends 100 percent pure creatine powder. Some companies add electrolytes and other ingredients, but tests indicate those do little to improve performance.

“Save money and buy creatine powder and [mix it with] fruit juice,” Kerksick says.

Fruit juice? That’s right—the sugar in the juice raises insulin levels, which helps increase creatine uptake into the muscle. Sports beverages work just fine too.

You need about 70 grams of simple sugars for every five grams of creatine, Greenhaff says. He suggests looking for a drink or supplement with 60 grams of carbs per 100 grams of product.

You’ll know the powder is of poor quality if it’s hard to dissolve and there’s residue at the bottom of your glass after you drink it. You want the powder in your muscles, not in the glass. If this happens, try a different brand.

And pills? While they’re effective, you often have to take a ton, especially during the creatine loading phase, in order to hit an effective dosage. If you love taking pills, go for it. For everyone else, powders seem to be the best bet.

Here’s a buyer’s guide for what to look for in a high-quality, effective creatine supplement.

What foods are high in creatine?

Just as our bodies produce creatine, the chemical is also found naturally in various foods.

“Creatine isn’t just found in supplements,” Brown says. “It’s actually found in beef, pork, and salmon.”

Try these recipes for creatine-rich meals:

Will creatine cause side effects with my kidneys, blood sugar, or cause muscular dystrophy?

Don’t believe everything you read on Reddit.

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Researchers are constantly studying creatine for its effectiveness and safety. That’s why many trainers and health experts support the use of creatine: Studies indicate it’s safe.

“Creatine is one of the most-researched sports supplements out there,” Kerksick says. “And there’s no published literature to suggest it’s unsafe.”

There have been anecdotal reports of kidney damage, blood sugar concerns, heart problems, muscle cramps and pulls, dehydration, and diarrhea, in addition to other negative side effects. But the key word is anecdotal.

“I’m not saying people don’t experience cramps, but I don’t believe it can be very common,” Greenhaff says. “If there were any major adverse side effects, we would have seen them by now.”

Some of these conditions can be caused by consuming too much of certain vitamins, says Tod Cooperman, M.D., president of ConsumerLab.com. “Too much vitamin C can cause diarrhea, and too much iron may lead to stomach problems,” he says.

To be safe, he recommends using creatine only if you are healthy and have no kidney problems. That’s because your kidneys excrete creatinine, a breakdown product of creatine.

So are there side effects of taking creatine?

It depends.

If you can get big without it, there’s no reason to use creatine.

“I wouldn’t recommend doing anything that would show minimal improvement and possible risk,” says Jim King, M.D., president of the American Academy of Family Physicians. “Weigh the negatives and the benefits before you try it.”

Kids under age 18 should avoid creatine, King says. “Children are still in a growing phase, and we’re not sure what impact creatine may have on muscles and bones as they grow,” he says. “I feel very strongly that middle and even high schoolers shouldn’t use it.”

Will creatine increase my power, strength, and body mass?

Here’s one thing all the experts can agree on: It’s impossible to say.

Creatine has different effects on every individual. Some people just don’t respond to creatine—it’s a genetic thing.

If you’ve started taking creatine, you should know if it works for you in about a week. If your training volume increases, it’s working for you. If not, you’re probably a non-responder, and taking the powder isn’t going to help you.

Diet is important. Since certain meats and seafood have high levels of creatine, vegetarians—i.e., people who don’t eat those creatine-rich foods on the reg—usually see a greater response. Those whose diets are highly carnivorous may see less change.

Of course, a healthy diet is key to anyone’s muscle-building plan. “If your diet is junk, there’s no point in adding creatine,” Kerksick says. “It’s better to eat good sources of carbohydrates and lean protein.”

In the end, creatine alone will not make you a bigger man.

“Only when combined with exercise does it improve the quality of training,” Greenhaff says. “You still have to do the work.”

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