C4 ENERGY COSMIC RAINBOW

Posted on August 21, 2025 | Last updated November 7, 2025

Released in February 2025, this is a review of "C4 ENERGY COSMIC RAINBOW".

Many people might find this design familiar. That’s right—"C4 ENERGY COSMIC RAINBOW" was introduced as a successor to the collaboration product C4 ENERGY SKITTLES, which had been available since 2022.

While the package design looks very similar, the contents have actually changed significantly. Let’s take a closer look at "C4 ENERGY COSMIC RAINBOW".

C4 ENERGY COSMIC RAINBOW

Manufacturer	Nutrabolt
Country of Origin	USA
Price	3.39 USD
Flavor	Popsicle, Lime, Lemon
Total rating	★★★☆☆

Author information Author: Energy Drink-kun

In 2001, while living in the United States, I encountered energy drinks through the dance scene and was deeply impressed. After returning to Japan, I found that energy drinks were considered novelty beverages, so I established a comprehensive website in 2013 to share the true appeal of energy drinks. As an energy drink enthusiast, I began drinking them seriously again, collecting over 8,000 varieties of energy drinks from various countries. I am also active as a critic and expert, receiving media interviews.

Flavor of C4 ENERGY COSMIC RAINBOW

When opened, a lemon-lime aroma spreads through the air. If you drink it expecting a renewal of C4 ENERGY SKITTLES, you’ll immediately notice the change in scent. Let’s give it a try.
Flavor of C4 ENERGY COSMIC RAINBOW
The first impression is a tangy lemon-lime candy flavor. It tastes just like gummies, hard candies, or popsicles, and it feels as though "C4 ENERGY COSMIC RAINBOW" reproduces the authentic SKITTLES flavor even better than its predecessor, "C4 ENERGY SKITTLES."

Although the sourness itself isn’t particularly strong, the “sour gummy-like flavor” comes from the way sweetness is kept to a minimum. By leaving only a trace of sweetness, similar to gummies or candies, the acidity stands out beautifully, creating a perfectly balanced tartness.

I initially thought "COSMIC RAINBOW" was released as a successor to SKITTLES with the same flavor, but upon tasting it, I found that not only the appearance but also the formula inside had changed.

Just like with other C4 ENERGY products that transitioned from collaboration editions to regular lineup items, "COSMIC RAINBOW" also features a modified flavor profile compared to its previous version.

Some people might not notice these flavor differences brought by the renewal, while devoted C4 ENERGY fans tend to pick up on them quickly. In any case, with its SKITTLES-inspired design and flavor that’s now even closer to the original candy, I believe many first-time drinkers of "C4 ENERGY COSMIC RAINBOW" will give it high marks.

Energy Ingredients of C4 ENERGY COSMIC RAINBOW

Energy Ingredients of C4 ENERGY COSMIC RAINBOW
Contains 200mg of caffeine, CarnoSyn Beta-Alanine, and BetaPower Betaine. Unlike other C4 series products, it does not contain citrulline or tyrosine.

Design of C4 ENERGY COSMIC RAINBOW

Design of C4 ENERGY COSMIC RAINBOW
The "C4 ENERGY COSMIC RAINBOW" design is based on the original C4 ENERGY layout, which combines the brand’s signature yellow color with the simple C4 logo. The upper part of the can features rainbow stripes that express the flavor’s theme.

Design of C4 ENERGY COSMIC RAINBOW
The four-line motif on the side of the can, a symbol of the C4 series, is depicted with a glossy, candy-like finish.

Let’s compare it with the previous "C4 ENERGY SKITTLES."
Design of C4 ENERGY COSMIC RAINBOW
Since the base design is very similar to that of "C4 ENERGY SKITTLES," most people familiar with the earlier version will immediately recognize it as its successor.

Although C4 ENERGY has not made an official announcement, it’s likely that "C4 ENERGY COSMIC RAINBOW" was released as a successor following the expiration of the SKITTLES collaboration license.

Design of C4 ENERGY COSMIC RAINBOW
The can’s surface texture has also been updated—from the smooth matte finish of the previous model to a glossy surface, similar to typical C4 ENERGY cans.

C4 ENERGY COSMIC RAINBOW Originally Released in the U.K.

While "C4 ENERGY COSMIC RAINBOW" was released in the U.S. in 2025, the same product name had already appeared earlier in the U.K.

It’s unclear whether the American version was inspired by the British one or if it’s an entirely different formula—but if I get the chance, I’d love to do a direct comparison and report on the differences.