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If you need a boost of energy before your workout, another cup of coffee sloshing around your gut isn’t the only option—pre-workout supplements combine ingredients for energy, focus and improved blood flow in powder form. All you need to do is add a little water, toss it back and go. C4 by Cellucor is a fan-favorite pre-workout supplement, so we’re pumped to take a closer look at how it shakes up to the other options on the market.

As the name indicates, pre-workout supplements are meant to be taken before a workout. They’re designed to enhance your athletic performance by giving you extra energy and focus. Most are also packed with nutrients that can help with muscle development; for example, Folic Acid helps with muscle development by improving blood flow to muscles. 

C4 is the original pre-workout supplement created by Cellucor—a 15-year competitor in the pre-workout game. The company says they designed C4 to increase your energy, muscle endurance and mental focus. Introduced to the market back in 2011, C4 is one of the most well-known and popular pre-workout supplements available. Although it may have smaller quantities of ingredients like caffeine than other C4 products, it’s a tried-and-true place to start for beginners and experts alike.

C4 Original Pre-Workout sells for $29.99 for 30 servings or $49.99 for 60 servings. Cellucor also offers a subscription for those who want C4 automatically shipped to them every 30, 60, 90 or 120 days. By becoming a subscriber, you get 30% off your first order and 20% off of every recurring order. You also receive free shipping, no subscription fees and the ability to change or cancel your order at any time.

About 20 to 30 minutes before your workout, take one level scoop of C4 powder mixed with six ounces of water. It’s that simple. However, it’s important to be mindful of what time of day you’re taking a pre-workout supplement. Caffeine is a key ingredient in the original C4 pre-workout formula. As many of us have learned (lying awake in bed at night), caffeine has a long half-life and can take five hours before its effect wears off. It may be best to take C4 and work out in the morning or mid-day. According to Kristen Williamson, RD, LDN, CPT, a registered dietitian and certified personal trainer, “Taking a pre-workout in the evening or late afternoon can impact sleep, which can impact recovery and undo all of your hard work.” And as we all know, sleep is crucial for recovery. 

If you’re the type of person who works out first thing in the morning, it’s a good idea to eat a snack with your pre-workout. On an empty stomach, Williamson warns that, “you are going into the workout completely fasted…So if you are taking a pre-workout, [with caffeine], it may give you some GI distress or make you feel jittery.” Williamson recommends mixing the pre-workout in a smoothie with some healthy carbs. “The downside to that is that it may take longer to feel those effects [from the pre-workout]. You may need to wait an hour, but [by having carbs before your workout] you’re also getting a jumpstart on that recovery piece as well.”

You can also take too much pre-workout. Excessive caffeine intake can lead to heart palpitations, increased blood pressure and impact long-term heart health. Be sure to monitor your coffee and other stimulant intake when you take a pre-workout. 

The original C4 Pre-Workout powder has amassed over 2,500 customer reviews on Amazon alone, with an average rating of 4.5/5 stars. Reviewers have mostly commented on taste, effectiveness and side effects. Here’s what they have to say:

Most people were happy with the sweet taste of the C4 powder. Reviewers especially enjoyed the Fruit Punch and Icy Blue Razz flavors. Some people felt that the mix was too sweet, so they added more water to dilute the sweetness.

Overall, reviewers felt that C4 boosted their energy, endurance and ability to do more reps. Some thought they built up a tolerance to the product, so it didn’t seem as effective with long-term use. To fix this, they switched to another C4 product with higher concentrations of the ingredients they liked, like caffeine.

Many reviewers noted that they felt a tingling or itching sensation after taking C4. Most reviewers said the sensation only lasted a few minutes or went away once their heart rate increased during their workout. According to Cellucor, this is a common experience that’s caused by beta-alanine. Other side effects included concerns over heart rate and jitteriness due to the amount of caffeine. Reviewers found that decreasing the dose resolved this issue. 

If your goal is weight loss, check out their C4 Ripped pre-workout line. The inclusion of Capsimax® (capsaicinoids from Cayenne) increases your metabolism and supports fat burning, according to Cellucor.

The C4 Extreme line helped launch the brand’s Project Clear Evolution (PCE) initiative. PCE products from C4 have “fully transparent” labels and no artificial dyes or flavors. C4 Extreme also has more caffeine than the original (200 milligrams versus 150 milligrams).

C4 says their Ultimate line is “the most powerful, all-inclusive C4 EVER.” It backs up that claim with 300 milligrams of caffeine per serving and the addition of endurance-boosting ingredients like CarnoSyn Beta-Alanine. And if 300 milligrams of caffeine isn't enough, the C4 Dynasty MMXX Pre-Workout powder is "proudly overbuilt" with 350 milligrams of caffeine, according to Cellucor.

Finally, if you’re a professional athlete, you may want to check out the C4 Sports line. The National Sanitation Foundation (NSF) tests and certifies this line of products for sports. NSF is an independent third-party organization that tests, inspects and certifies supplements. The Certified for Sports program verifies that the C4 Sports pre-workout products don’t contain any substances that major athletic organizations ban.

Along with their pre-workout supplements, Cellucor also offers protein powders, fat burners, amino acids, testosterone boosters and branded gear. 

Disclaimer: You should consult with your health care professional before starting a pre-workout supplement, especially if you are pregnant or nursing, taking other supplements or prescription medications, have heart, kidney or liver disease, or are diabetic. This product should not be taken by anyone under the age of 18, and you should discontinue use if you experience any adverse reactions.

In theory, anyone who works out could benefit from taking a pre-workout supplement. Who couldn’t use a boost in mental focus, endurance or recovery? But according to Williamson, “the number one thing to think about is the type of exercise you are doing before you use a pre-workout.” Will you be doing more aerobic exercises (e.g. jogging, cycling or walking) or anaerobic exercises (like sprints or heavy weightlifting)? Williamson says, “A lot of pre-workout supplements are geared more towards anaerobic workouts, or short bouts of intense exercise. It’s not that a pre-workout can’t be used for aerobic exercise, you just may not see the same benefit as you would for anaerobic exercise.”

This may sound crazy, but the science makes sense. During aerobic exercise, the body moves in a relatively consistent and continuous way. During these types of workouts, the muscles in our body can rely on the air we breathe to supply them with the necessary energy to move.

During anaerobic exercise, our muscles need more than just air to supply them with the necessary energy to power through the short and intense nature of these workouts. Instead of air, muscles break down sugar—like carbs—to fuel your workout. This breakdown of sugar results in a buildup of lactate and hydrogen ions. It’s the buildup of hydrogen ions, not lactate, that’s responsible for the acid that makes our muscles burn. Pre-workout supplements are specifically designed to reduce acid buildup during workouts. This is why people who do more anaerobic exercise typically see more benefits from using a pre-workout. 

Before taking any supplement, the first question you should always ask yourself is, what’s my goal? What benefit am I looking for? Cellucor offers a lot of pre-workout options, and the biggest differences among them are the active ingredients. Each ingredient has a primary function, so knowing what benefit you want, like increased focus, can help you choose the right product.

If you’re a weightlifter or sprinter and want to level up at the gym, a pre-workout may be just what you need to hit your performance goals. Cellucor’s C4 Pre-Workout powder has been a consumer favorite since it was launched over a decade ago, and it’s worth a try. Just remember to track the amount of caffeine you’re consuming each day and don’t blow past the recommended daily usage. 

Dr. Nicole Loew PhD, RN and Co-Founder of Woman Centered Health, is a nurse researcher, podcaster and writer who works to put research in the hands of people who need it most. This author is writing sponsored content paid for by Pillar4 and not affiliated with Sports Illustrated.