C4 Ultimate is the high-powered version of C4: 300mg of caffeine, a high dose of beta-alanine, several pump ingredients and an electrolyte panel, all in one scoop. It's built for people who want energy, pumps and strength from a single tub.

We went through every ingredient and dose to work out what it will actually do for you, not just what the label promises.

C4 Ultimate Review: The Quick Verdict

Overall score: 7.6/10

Here's the deal with C4 Ultimate: it's a strong all-rounder. Energy, pumps and strength all score well, and the main ingredients (caffeine, beta-alanine, citrulline and nitrates) are dosed at or close to the amounts the research uses. Focus is the one area that lags, because it leans on the caffeine rather than a real focus stack.

The trade-off is intensity. With 300mg of caffeine and a lot of beta-alanine, this is not a gentle pre-workout.

Honest take: a well-dosed, high-stim pre-workout that delivers on energy, pumps and strength. Focus is the soft spot.

You'll probably like it if: you're used to caffeine, you want noticeable pumps and strength as well as energy, and you'd rather have one scoop do the job than stack extras.

Maybe skip it if: you're sensitive to caffeine or tingles, you want a calm, laser-focus feeling, or you train late in the evening.

C4 Ultimate at a Glance

What Is C4 Ultimate?

C4 Ultimate is Cellucor's top-tier pre-workout. Every ingredient is listed with its amount, so you can see exactly what's in each scoop.

Quick facts:

• You take: 1 Scoop (20g)
• Per tub: 20 servings
• Price: $39.99 a tub ($2.00 per serving)
• Caffeine: 300mg per scoop
• Stimulant level: High

C4 Ultimate Energy: Will It Actually Wake You Up?

Score: 8.2/10

Yes, and this is the headline. With 300mg of caffeine you're getting roughly three cups of coffee's worth of kick in one scoop, which is a strong, obvious lift.

• Caffeine (300mg): does almost all of the work here. It sits inside the 200-400 mg range that research uses, right in the middle of it.
• Methylliberine (50mg): a caffeine-like compound that's meant to make the energy feel smoother. It's a small dose, so it adds a little, not a lot.
• Theacrine (10mg): a small amount of another caffeine relative. Research uses far more, so think of it as a label touch rather than a real contributor.
• Tyrosine (1000mg): an amino acid that supports mental energy under stress. It's about half of the research dose.

What it'll feel like: a strong kick that shows up within about 15 to 45 minutes and carries you through a hard session. If you aren't used to this much caffeine, it can feel jittery.

Honest take: a big, dependable kick, and almost all of it is the caffeine.

C4 Ultimate Focus: Will You Feel Locked In?

Score: 6.3/10

Partly. Focus is C4 Ultimate's weakest area, and it's mostly the caffeine again.

• Tyrosine (1000mg): supports focus when you're tired or stressed, but this is about half of what research uses.
• Huperzine A (0.05mg): a plant compound used for focus. Research uses closer to 200mcg, so you're getting only a fraction of a real dose.
• Methylliberine (50mg): a small extra on the caffeine side of things.

There's no theanine or other calming focus ingredient to take the edge off the caffeine, so the focus you get is the alert, wired kind.

What it'll feel like: awake and alert, but not especially calm or dialed in. Some people find that edge sharpens their training, others find it scattered.

Honest take: you'll feel switched on, not locked in.

C4 Ultimate Pumps: Will You Look and Feel Bigger?

Score: 7.9/10

Yes, this is a real strength. Several pump ingredients are in here, and two of them are close to full doses.

• Citrulline (3000mg): helps your body make more nitric oxide, which opens up blood vessels and sends more blood to your muscles. Research points to around 4000mg, so this is a good chunk of a full dose.
• Nitrates (468mg): open up blood vessels by a different route than citrulline, and this is close to the 500mg that research uses. Together with citrulline, they do most of the pump work.
• Arginine (3000mg): aims at the same goal, but it's absorbed poorly, so it adds less than the number suggests.
• PeptiPump (200mg): a branded lentil peptide that helps blood vessels relax. It's a newer ingredient without much human research behind it yet.

The electrolytes (225mg of sodium, 190mg of potassium and 20mg of magnesium) help your muscles hold on to fluid, which helps the pump look and feel fuller.

What it'll feel like: full, tight muscles by the second or third set, especially on higher-rep work.

Honest take: a proper pump, from the right ingredients at near-full doses.

C4 Ultimate Strength and Performance: Will You Lift More?

Score: 8.1/10

This is one of its best areas, and the reason is the beta-alanine.

• Beta-alanine (3200mg): helps your muscles handle the burn during hard sets, and it's also what causes the tingly feeling. Research uses 3.2-4.5 g a day, so this is at the low end of that range. It works best taken consistently, not as a one-off.
• Creatine (1032mg): a real helper for strength, but most studies use 5,000mg. Think of it as a bonus, not a replacement for a creatine supplement.
• Betaine (1250mg): supports work capacity. Research uses 2500mg, so this is about half.
• Citrulline, nitrates and caffeine add to the effect too, because better blood flow and more alertness help you push harder.

What it'll feel like: a clear edge late in your sets, with less fade across the session, plus a good deal of tingling.

Honest take: strong on strength and endurance, helped by a high beta-alanine dose.

What Do Customers Say About C4 Ultimate?

C4 Ultimate gets strong feedback for its energy and its pump. Reviewers talk about a "way more noticeable boost" than other pre-workouts, and many call it effective if you're comfortable with a lot of caffeine. At 300mg a scoop, not everyone is. One iHerb reviewer warned "300 mg beware."

However, customer feedback highlights three trade-offs worth knowing.

First, flavor is surprisingly divisive. Some say the flavors "legit match the drinks" they're named after, but customers seem to have absolutely hated Jolly Rancher Cherry. On the Vitamin Shoppe, 9 of its 17 ratings were one star when we checked, with reviewers saying it "tastes like cough syrup" and they "can't get past the bad taste."

Second, some long-time C4 users prefer the older version. Reviewers call the current one "a tasteless shell of its former self." These are personal experiences, not proof the formula got weaker.

Third, the price is a common complaint. At 20 servings per tub, it's about $2.00 a serving, which feels steep to frequent users.

One more thing worth knowing: "no crash, no jitters" is the most repeated line, and it's mostly in reviews the brand collected, which also appear on Walmart, Target and the Vitamin Shoppe. Independent reviewers are more mixed. One Amazon buyer felt "very tweaked out" on a full first scoop, and another warned you'll get "jittery too" if you don't start training within about 10 minutes.

Honest take: C4 Ultimate delivers the strong stimulant hit most customers expect. The biggest complaints aren't about whether it works, but about flavor, value and how the newer version compares with the old one. If you're new to 300mg, start with less than a full scoop.

Customer feedback is subjective and may cover different flavors or formulations. Retailer reviews are separate from our ingredient-based formula score.

C4 Ultimate Side Effects

Tingles and pins and needles. C4 Ultimate contains 3200mg of beta-alanine, a genuinely high single dose. A controlled study at this same amount found the sensation unpleasant for every participant tested, and intolerable for some. Expect strong tingling across your face, neck and hands starting around 15 minutes in. It's still harmless and fades within an hour, but if you're trying it for the first time, know it can be intense. Splitting the dose or taking it with food takes the edge off. How strongly you feel it also depends partly on your size: people with lower body weight tend to reach higher blood levels from the same dose, so if you're smaller, expect it to hit harder.

Jitters and a racing heart. At 300mg of caffeine, jitteriness, a faster heartbeat and a wired, restless feeling are the most common complaints, especially if you're not caffeine-adapted or you take it fasted. Research shows anxiety risk rises meaningfully in this range compared to lower doses. Start with half a scoop the first time. If you already drink coffee during the day, count that toward your total. If caffeine has always hit you harder than it seems to hit other people, you may be a slow caffeine metabolizer, and the same dose will hit harder and last longer for you.

Stomach upset. C4 Ultimate contains 3000mg of plain L-arginine, which is more prone to causing cramping or loose stools than citrulline, because the intestines have a harder time absorbing large arginine doses. Mixing it into more water and drinking it slowly rather than shooting it can help.

Sleep. Give yourself at least 8 to 10 hours before bed.

Who should skip it. Anyone pregnant or breastfeeding, under 18, sensitive to stimulants, or managing blood pressure, heart or anxiety conditions should talk to a doctor before using C4 Ultimate. The same goes if you take prescription medication, because stimulant interactions are the most common problem.

Should You Buy C4 Ultimate?

Choose C4 Ultimate if:

• You want energy, pumps and strength from one scoop, with the main ingredients at or near research doses.
• You train hard and often, and you're comfortable with 300mg of caffeine.
• You like having electrolytes, tyrosine and betaine in your pre-workout.
• You don't mind strong tingles from a high dose of beta-alanine.

Don't choose C4 Ultimate if:

• You're new to pre-workouts or sensitive to caffeine. 300mg is a lot to start with.
• You want calm, locked-in focus. Focus is its weakest area, at 6.3/10.
• You want mild tingles and an easy stomach. This formula has a lot of beta-alanine and 3000mg of arginine.
• You're price-sensitive. It works out to $2.00 a serving.

Beginners: start with C4 Original at one scoop (or even half). A full scoop of C4 Ultimate is a lot to start with.

Training in the evening? C4 Original's lower caffeine is easier to fit in. C4 Ultimate's 300mg will be in your system for hours.

Need creatine in your pre-workout? Neither C4 Ultimate (1032mg) nor C4 Original has a real dose. You'll want to take it separately.

Tested athlete? Neither C4 Ultimate nor C4 Original is NSF certified. Look at C4 Sport instead.

Pre-Workouts Similar to C4 Ultimate

• Want more focus with less caffeine? Transparent Labs Bulk scores 7.8/10 with 200mg of caffeine, at $1.67 a serving. Read our Transparent Labs Bulk review.
• Want a stronger all-round formula? NutraBio PRE scores 8.6/10 with 250mg of caffeine, at $2.50 a serving. Read our NutraBio PRE review.
• Want a cheaper high-stim option? Redcon1 Total War scores 7.0/10 with 320mg of caffeine, at $0.93 a serving. Read our Redcon1 Total War review.
• Tested athlete? C4 Sport is NSF Certified for Sport and scores 5.3/10 at $24.99 a tub. Read our C4 Sport review.

C4 Ultimate Quick Answers

Is C4 Ultimate a good pre-workout? C4 Ultimate is a strong pre-workout that scores 7.6/10 on our scale. It has near-full doses of its main pump and strength ingredients and a big caffeine kick, with focus as its weakest area.

How much caffeine is in C4 Ultimate? C4 Ultimate contains 300mg of caffeine per scoop, which is roughly three cups of coffee. If that's more than you want, half a scoop is 150mg.

Does C4 Ultimate have creatine? C4 Ultimate contains 1032mg of creatine per scoop. That's well below the 5,000mg used in most studies, so you'd need to take creatine separately for the full benefit.

Does C4 Ultimate have beta-alanine, and why do I tingle? C4 Ultimate contains 3200mg of beta-alanine per scoop, a high dose that sits at the low end of the 3.2-4.5 g range used in research. The tingling is a harmless pins-and-needles feeling caused by the beta-alanine, and it usually fades within the hour.

Is C4 Ultimate a high-stim pre-workout? C4 Ultimate is a High-stimulant pre-workout. It contains 300mg of caffeine plus small amounts of methylliberine and theacrine.

Does C4 Ultimate have citrulline? C4 Ultimate contains 3000mg of citrulline per scoop, which is a good share of the 4000mg that research points to for the full pump effect.

Does C4 Ultimate have electrolytes? C4 Ultimate contains 225mg of sodium, 190mg of potassium and 20mg of magnesium per scoop. That helps your muscles hold on to fluid, but it isn't a full hydration drink.

How many scoops of C4 Ultimate should I take? Start with one scoop of C4 Ultimate, or even half if you're sensitive to caffeine. Don't go past what your tub's label recommends.

Is C4 Ultimate good for beginners? C4 Ultimate isn't ideal for beginners, because it contains a high 300mg of caffeine and a lot of beta-alanine. If you do try it, start with half a scoop.

Does C4 Ultimate taste good? Opinions on C4 Ultimate's taste are split. Some reviewers say the flavors "legit match the drinks" they're named after, but customers seem to have absolutely hated Jolly Rancher Cherry. On the Vitamin Shoppe, 9 of its 17 ratings were one star when we checked, with reviewers saying it "tastes like cough syrup" and they "can't get past the bad taste."

Is C4 Ultimate NSF certified? C4 Ultimate is not sold as NSF Certified for Sport. Cellucor's NSF certification is on a different product, C4 Sport, so tested athletes should look there instead.

Is C4 Original or C4 Ultimate better? C4 Ultimate scores higher than C4 Original on our scale, 7.6/10 against 5.3/10 at one scoop, but it also has a lot more caffeine, so it depends on how much you want. See our C4 Original vs C4 Ultimate comparison for the full breakdown.