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Core Extreme Nutrition RX'd Review

The long-anticipated sequel to Core Extreme Nutrition’s BOOST Pre-workout is here and we FINALLY had an opportunity to review it. Enter CEN’s RX’D Pre-Workout, the power amplifying, endurance enhancing pre-workout with clinically dosed ingredients and a fully disclosed label. That’s right, RX’D complete 10-ingredient formula is listed on the label with the exact amounts you are getting per serving. We were more than excited for the opportunity to review RX’D, especially after BOOST had such a huge impact with us. Not only does CEN’s new formula look amazing, but everything that is included in RX’D has multiple scientific studies backing the ingredients' effectiveness and benefits. Oh, and did we mention, their Bombsickle flavor is actually pretty bomb as well! All jokes aside, we loved CEN’s new reformulated pre-workout RX’D for many reasons. Let’s take a look at why this sequel may be even better than the original.

cen rx'd review


We weren’t 100% sure what to think at first when we saw the bombsickle flavor but it did not let us down. The initial flavor you get when you mix 1 scoop (17.28g) in 16oz of water is pretty sour; not like warheads candy sour, but definitely a blue raspberry sour. Once the initial sourness subsides, you are left with a pretty similar taste to a bomb pop popsicle. If you could imagine melting one of those popsicles so that all of the flavors melt into one sweet and slightly sour drink, that’s what you are getting with this flavor. CEN definitely created a flavor we have not tasted before and most importantly, they nailed it. We can’t really come up with another comparison to any other products we have tried because this one is very unique in all the rights ways. We have got to say, CEN has done a phenomenal job in their labs creating pre-workout products that have enjoyable and unique flavors. Even though the product does use natural and artificial flavors, the product itself does not have any chemically flavors or aftertaste to it. Another amazing job by CEN’s flavor department with RX’D.


Initial mixability on this product is great. We noticed no clumping or chunks visible after a few shakes in about 16oz of water. The product mixes great and is right up there with some of the other fast dissolving pre-workouts that we have reviewed. One thing we did note was after letting the product sit for a while during the workout, there was a little bit of residue on the bottom of our shaker bottles. After some experimenting with the water content when mixing, we found that mixing the full scoop in about 22-26oz of water is ideal for a smooth, grit free pre-workout cocktail. To ensure this, we shook up 1 scoop in about 24oz of water and let the shaker sit for a bit to find that there was no remaining powder left at the bottom of the cup. If you’re the type of individual who likes to throw a scoop of any pre-workout in 8oz of water and slam it down, then you have nothing to worry about. But for those who like to enjoy the flavor and taste of your pre-workout while sipping it on the way to the gym, we suggest 24oz of water.


cen rx'd review label

Citrulline Malate 2:1

CEN upped the citrulline content from their past pre-workout and included 6g at a 2:1 ratio in RX’D. We were happy to see that CEN decided to go with a 2:1 ratio rather than 1:1 because of the additional citrulline which DOES provide a performance benefit. For those who do not know, citrulline studies have shown performance enhancement in a couple of ways. The first being that it aids in performance by reducing muscular fatigue throughout your workout. This is done via the movement of ammonia and lactate out of the muscles. Not only does citrulline help with longer workouts or even two-a-day workouts, but it can also benefit you in by speeding up recovery time between sets and helping you to add a couple extra reps on higher-rep sets. This can also benefit you after your workouts by reducing muscle soreness 24-48 hours after your session. This will in turn allow you to train harder and recover better between workouts. Secondly, citrulline has been said to increase blood levels of l-arginine in the body which would theoretically increase blood flow throughout your body. This can lead to better pumps during your workout and better recovery post-workout.

Peak O2

Peak O2 is a newer compound that is becoming more and more popular in pre-workouts as of late. Peak O2 is made up of 6 different mushroom strains that are farmed and grown organically here in the US! These mushrooms are considered powerful adaptogens which aids athletes in their ability to adapt to stressors, both physical and emotionally. These strains contain high levels of beta-glucans and antioxidants which help to rid the body of oxidative stress and free radicals. So, what does this mean for you? Well in a 2g dose of Peak O2, studies have shown that it can improve:

  • Workout duration

  • Time to exhaustion

  • Maximum power output

  • Peak Strength

  • Anaerobic peak power

  • Oxygen utilization during exercise

  • Exercise capacity

All of these aspects make Peak O2 the perfect addition to RX’D.

Beta Alanine

We all have a love/hate relationship with beta alanine: we love the performance benefits but hate that it makes our faces tingle. Well, in RX’D, you don’t have to worry about the paresthesia (tingles), but you will have to worry about your workouts going longer than expected! At 2g of beta alanine per serving, we didn’t experience any sort of tingly feeling, but most users can avoid that by eating a small meal or having a granola bar or the like when taking it. Multiple studies have shown that, like citrulline, beta alanine can help to improve your workouts by reducing the muscular fatigue, especially in exercises lasting longer than 1-2 minutes. This is extremely beneficial if taken before cardio, during longer workouts, or in used in conjunction with workouts containing supersets or cluster sets.


1g of Taurine was added into RX’D and while not necessary, it does have a positive impact on your performance. Studies have shown that Taurine can increase blood flow while not increasing blood pressure, and can also increase your exercise capacity. While not a majorly noticeable effect, the increased blood flow can also aid with recovery in the long term, and of course can help with the pump during your workout. Studies have also shown that taurine can help with fat oxidation and reduction of muscle soreness, but unfortunately this occurs at a higher dosage than is used in RX'd. We like this addition into RX’D for its blood flow benefits to really help deliver a pump during your workout.

Betaine Anhydrous RX’D contains 1.5 grams of betaine anhydrous per serving. We would love to see a little bit closer to 2.5g for maximum benefit but 1.5g will definitely show performance enhancement during your workouts. Studies suggest that betaine anhydrous, over time, can improve power output and strength gains. Although there is not a lot of concrete evidence discussing HOW betaine works, the studies have shown results over months of continuous use. Although “continuous use” is the important part when dosing betaine, you’ll get at least 30 servings worth out of RX’D.

Creatine HCL

Creatine: The king of supplements in the health and fitness world. While creatine monohydrate will probably always be the king of creatine, creatine HCL has made its way into the supplement industry and has left a big mark. Creatine HCL is creatine that is bound to a hydrochloride group which enhances its stability. This allows for better absorption at a lower dose which is why we see creatine HCL dosed lower (2g) than its monohydrate counterpart (5g). It has all the benefits that creatine monohydrate has (increased strength gains, increased size/weight gain, power output over short periods) without the negative effects such as bloating, stomach issues, diarrhea, and bad taste. We’re glad CEN got on the Creatine HCL train and strayed away from traditional monohydrate.

Alphasize (Alpha GPC)

Alpha-Glyceryl Phosphoryl Choline, is one of the greatest cognitive enhancers that the supplement industry has ever seen. Studies have shown it aids in power output, mind-to-muscle connection, memory enhancement, recall, and other cognitive functions. Alpha GPC has also been shown to increase ability to make quick and sudden movements, such as reaching for your shaker cup that you noticed you almost just knocked over! With Alphasize you wouldn’t have spilled it because your reflex speed and time is also increased. The mind-to-muscle connection is single handedly one of the most important aspects of anything fitness related and 300mg of Alphasize is going to give you all the benefits listed above, and then some. We applaud CEN for putting Alpha GPC into RX’D because it is truly a game changer.

Caffeine Anhydrous

What’s there to say that hasn’t already been said about caffeine. Caffeine amplifies all of the other ingredients’ effects, while bringing some of its own to the table of course. We love caffeine for its focus factor, increase in cognitive functioning, mood elevation, increase in physical and mental performance, and so much more. RX’D has 250mg of caffeine anhydrous in one serving.

Theacrine (Teacrine)

Teacrine is one of the hottest supplement ingredients on the market today. More and more companies are starting to include this beast int their products and consumers couldn’t be happier. This ingredient can be stacked with just about any other ingredient and it not only increases those ingredients effects, but it brings its own benefits to the table. Users have reported, increases in physical and mental energy, mood enhancement, improved cognitive functioning, feelings of motivation, physical performance, and memory enhancement; and that’s just to name a few benefits. The real benefit is that it amplifies any other ingredient that is taken with it, caffeine especially. And, unlike caffeine which users can develop tolerance to requiring larger and lager amounts for efficacy, Teacrine does not require increases in dosing to remain effective. At 125mg per serving, you’re looking at a huge increase in both physical and mental performance. Who wouldn’t want that?


Last but certainly not least, RX’D contains a 25mg serving of Astragin. While this ingredient doesn’t directly impact performance, what it does do is make sure all the other ingredients are being delivered into your system the best they can. Astragin is a top-quality absorption enhancer and bioavailability preserver when paired with other ingredients. What this means is that Astragin makes sure that the nutrients you want are being delivered into the blood stream safely, effectively, and at the amounts that should be getting delivered. Essentially, Astragin is the vehicle that provides all the goodies inside RX’D into your blood stream to make sure you’re getting exactly what the nutrition label says.


Right now, if you look to purchase RX’D off of Core Extreme Nutrition it is $49.99 for a 30 servings tub. However, when you use the code MAH15, you get 15% off of your whole order. Plus, with CEN’s latest deal anything over $49.98 ships for free as well!

While this seems to be towards the expensive side for a 30 serving tub of pre-workout, you truly have to look at everything that you are getting within the tub to understand the deal you’re getting! Not very often do you see a company provide you with a fully transparent label filled with tons of clinically backed ingredients.

cen rx'd review

What do we think about its performance?

CEN, you’ve done it again. First with Boost and now with RX’D. This is a juiced-up version of the original Boost with additional goodies that make it so worth the price tag. Let’s start at the top of our experiences with RX’D.

We stuck with one scoop before our workouts and although we are pretty stimulant tolerant, this stuff hits pretty hard. Energy from RX’D is clean, no jitters, and it doesn’t make you run to the bathroom 15 minutes into training. Energy lasts about an hour or so after your workout is done (for us, we had energy for about ~3 hours) with absolutely no crash. That’s the real measure of a pre-workout and something that separates the “good” from the “great”: RX’D is great. You truly do get a tunnel vision feeling as well as a heightened sense of focus, and even a little bit of an aggressive attitude when in the weight room. We felt that, because of all this, RX’D had an impact on our strength in the weight room as well our endurance levels and our ability to push past our old plateau points. Many of our workouts lasted longer than an hour and a half and although many people stick to an hour workout, the energy for more will be there. Plus, I’m sure many of you reading this have been too tired or sore to stretch, train abs, or do mobility work after your workout; RX’D ensures that you have enough left in the tank to take care of the smaller things that lead to bigger results.

Overall, we loved RX’D. If you haven’t stopped reading this to head over to CEN’s website and use MAH15 to get 15% off your order. RX’D was a hit with us and we can guarantee it will be a hit with you as well.



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