If you've spent any time in the gym, chances are you've heard about creatine ― the holy grail of supplements among seasoned weightlifters. But even if you're aware that it's recommended by fitness professionals and enthusiasts alike, how much do you really know about what goes into your shaker bottle every day?

"Creatine is the most commonly used performance supplement," says Dr. Vijay Jotwani, a sports medicine doctor at Houston Methodist. "It's a reasonable one for a lot of our patients to take since it has studied benefits. It's also not banned among competitive athletes ― unlike some performance-enhancing supplements."

Still, you might have some questions about creatine supplementation. Dr. Jotwani answers the most common ones below.

What does creatine do?

Creatine isn't just a dietary supplement: your body naturally makes it every day ― primarily storing it in your muscles, where it can be used as a quick source of energy when needed.

"Creatine is particularly helpful during short bursts of intense activity, like weightlifting, sprinting or high-intensity interval training (HIIT)," explains Dr. Jotwani. "Available as an immediate energy source, it's used to quickly power muscle contractions."

It's easy to see why fitness-minded folks would be interested in muscles having access to plenty of creatine. The body makes about 1 gram per day, and small amounts can also be consumed through certain foods like seafood and red meat. But for those who wish to load their muscles with even more creatine than that, supplementation is all but required.

But do creatine supplements really work?

"Creatine isn't just one of the most widely recommended supplements in the fitness industry, it's one of the more researched ones, too," says Dr. Jotwani. "Several studies demonstrate the beneficial role of supplementation in people who exercise."

Creatine benefits include:

• Enhanced exercise performance – helps boost muscle strength and power during short bursts of intense exercise
• Improved muscle recovery and growth – helps increase water content in muscle cells, aiding protein synthesis

That said, it's only helpful if you plan to exercise.

"Creatine's benefits come from what it helps you accomplish in the gym, whether that's lifting heavier weights, completing more reps or finding explosive speed," explains Dr. Jotwani. "Your body then responds to this by building more muscle. Creatine may also make the repair process work more efficiently as muscle rebuilds."

In other words, taking creatine has nothing to offer if you decide to skip your workout and sit on the couch instead. It's also unclear if creatine helps with other forms of exercise, such as long-distance running.

"As of now, we can't say with certainty that creatine benefits endurance exercise," adds Dr. Jotwani. "There are studies showing it may, but also ones showing it may not — so the jury is still out."

Is creatine safe?

Could creatine be bad for you? Are there side effects to be aware of? For a supplement that's often taken daily, its safety profile is likely of high importance to you.

For starters, know that ― unlike medications ― supplements aren't regulated by the Food & Drug Administration (FDA). This means you'll need to do your own research to be sure you're taking a quality creatine product. Be sure to choose one that's undergone testing and is certified by an independent third-party laboratory, such as NSF. This helps ensure that what's on the label is what you're actually ingesting (and all you're ingesting).

As for creatine's side effects, they can include diarrhea and muscle cramping. The supplement can also sometimes increase a person's blood test numbers related to kidney function.

"I don't disagree with people taking creatine," says Dr. Jotwani. "It's a fairly straightforward supplement. But like all supplements, it's not completely without consequence or risk. If you experience side effects, a sports medicine doctor can guide you through it."

And it might not be safe for everyone, such as those with kidney or liver issues. Dr. Jotwani recommends consulting your doctor before taking a creatine supplement.

"Your doctor can help evaluate whether it's safe for you to take and, if it's not, help you find alternative ways to achieve your fitness goals," adds Dr. Jotwani.

Should you take creatine before or after a workout?

Creatine is effective. It's also generally safe for most people. But what about the actual logistics, like when to take creatine. More specifically, is it better to take it before you exercise? Or after?

There's no clear answer yet, but most experts agree it's reasonable to assume that it's best to take creatine close to the time of your workout, whether that's before or after.

The most important consideration to the timing of creatine supplementation is likely consistency of intake, since this can help ensure your muscles stay well saturated. That said, be sure to follow recommended dosage instructions. It's also important to maintain adequate hydration throughout the day. This can not only help minimize creatine's side effects but also ensure its effectiveness.