Is Celsius Bad for You?

For most healthy adults, Celsius is not bad for you in moderation. One 12 oz can a day sits well within the FDA’s 400 mg caffeine guideline, and with zero sugar and 10 calories it’s a better choice than most full-sugar energy drinks.

But Celsius isn’t a health drink either. Each can has 200 mg of caffeine, about the same as two small cups of coffee, plus an artificial sweetener and a proprietary blend that doesn’t show you the dose of each ingredient. It can be a bad choice for teens, pregnant women, people sensitive to caffeine and anyone with a heart condition, and drinking several cans a day is where the real problems start.

Below, we go through the actual risks one by one, what the evidence says, how Celsius compares with other drinks, and how to drink it sensibly if you choose to.

The Short Version

Sources: Celsius label via H-E-B; Barista Life for Celsius Essentials.

New to Celsius? Start with our guide to what Celsius drink is, including the full ingredient list.

Concern 1: Caffeine (the Big One)

Caffeine is the main reason people ask whether Celsius is bad for them, and it’s a fair question.

A 12 oz can of Celsius has 200 mg of caffeine. For context:

• The FDA says 400 mg a day is an amount not generally linked to negative effects in healthy adults (FDA).
• One Celsius is half of that.
• Two Celsius cans hit the full 400 mg on their own, before any coffee, tea, soda or pre-workout.

That’s why the can tells you not to exceed two servings a day. In practice, if you also drink coffee, one can of Celsius is a more sensible daily limit.

What too much caffeine feels like. The FDA lists a faster heartbeat, palpitations, higher blood pressure, trouble sleeping, anxiety, jitteriness, an upset stomach, nausea and headaches as signs of too much caffeine (FDA). If you notice any of these after a Celsius, cut back.

Sleep is the hidden cost. Caffeine’s effects peak about 30 to 60 minutes after you drink it and its half-life can be up to about 5 hours (Healthline). A can at 4 p.m. can still leave around 100 mg in your system at 9 p.m. Poor sleep then makes you reach for more caffeine the next day. Stop drinking Celsius at least six hours before bed.

Concern 2: The Proprietary Blend

Celsius lists its key active ingredients as a “MetaPlus Proprietary Blend”: taurine, guarana extract, caffeine, glucuronolactone, ginger extract and green tea extract (H-E-B label).

The label gives the total caffeine (200 mg) but not the amount of each other ingredient. That’s allowed, but it means you can’t judge the dose of guarana, green tea extract or ginger. Registered dietitian Jamie at The Balanced Nutritionist lists the unknown doses as one of Celsius’s main drawbacks.

Does it hurt your liver? The question comes up because concentrated green tea extract supplements have been linked to rare cases of liver injury. The Balanced Nutritionist reviewed the NIH’s LiverTox database and concluded that occasional Celsius use carries a low liver risk (The Balanced Nutritionist). If you have liver disease, ask your doctor first.

Concern 3: Artificial Sweetener

Most Celsius flavors are sweetened with sucralose (H-E-B label). Sucralose is approved for use in food in the US and adds no calories or sugar.

Some people prefer to avoid artificial sweeteners because research on their long-term effects, including on gut bacteria, is still developing. If that’s you, Celsius isn’t a good fit; look at plain coffee or tea instead.

The upside is real too: by using sucralose, Celsius avoids the 54 grams of added sugar you’d get in a 16 oz can of original Monster (H-E-B).

Concern 4: The Marketing Claims

Celsius calls itself a “fitness drink” and has long claimed it can accelerate metabolism and burn body fat (Sporked). The evidence behind that is thin. The research Celsius points to includes a small, company-funded study from 2010 that found modest effects in exercising men (The Balanced Nutritionist). The can itself says its claims “have not been evaluated by the FDA.”

This isn’t dangerous in itself, but it matters if you’re drinking several cans a day expecting weight loss. You’ll get the caffeine side effects without the promised fat loss.

Concern 5: The “No Preservatives” Lawsuit

In 2022, Celsius agreed to a $7.8 million settlement in a class action that claimed it falsely advertised its drinks as having “No Preservatives” while they contained citric acid (MediaPost). Celsius argued the citric acid was there for flavor, and the court didn’t rule for either side; the two sides settled to avoid the cost of a trial.

This was a labeling dispute, not a safety finding. Citric acid is a common, safe ingredient. But it’s a fair reminder to read the label, not the marketing.

Who Should Avoid Celsius?

The Celsius can itself says it is not recommended for people who are caffeine sensitive, children under 18, or women who are pregnant or nursing (H-E-B label). Based on the caffeine content, these groups should also be careful:

Is Celsius Worse Than Other Energy Drinks?

Not really. Compared with other popular options, Celsius is middle of the pack for caffeine and better than most for sugar.

Sources: H-E-B (Celsius), H-E-B (Monster), Caffeine Informer (Monster Ultra), H-E-B (Red Bull Sugarfree), Giant (Rockstar Pure Zero).

If you want a zero-sugar drink with less caffeine per can, Monster Ultra (150 mg) or Red Bull Sugarfree (80 mg) are gentler. Our guide to the healthiest energy drinks ranks the options, and our list of energy drinks with the most caffeine shows which ones to treat with care.

How to Drink Celsius Safely

If you enjoy Celsius, these simple rules keep the risks low:

1. One can a day is plenty. Never more than two, as the label says.
2. Count all your caffeine. Coffee, tea, soda, pre-workout and Celsius all share the same 400 mg budget.
3. No Celsius within six hours of bed.
4. Don’t drink it on an empty stomach if caffeine tends to upset your stomach.
5. Drink water alongside it, especially when you exercise.
6. Don’t mix it with alcohol.
7. Skip it if you’re under 18, pregnant or nursing, as the label advises.

Is Celsius Better Than Coffee?

Not necessarily. Plain black coffee has no sweetener, no proprietary blend and almost no calories, and you control the strength. Celsius is more convenient, comes cold and flavored, and has a fixed, clearly labeled 200 mg of caffeine. If you like the taste and drink one a day, it’s a reasonable swap. If you’re trying to keep things as simple as possible, coffee or tea wins.

FAQs

Is it bad to drink Celsius every day?

One can a day is generally fine for healthy adults, since 200 mg is half of the FDA’s 400 mg guideline. Problems are more likely if you drink two or more cans or combine Celsius with other caffeine.

Is Celsius bad for your heart?

Caffeine can raise heart rate and blood pressure, especially at high doses. If you have a heart condition or high blood pressure, ask your doctor before drinking Celsius.

Is Celsius bad for your kidneys?

There’s no strong evidence that one can a day harms healthy kidneys. If you have kidney disease, check with your doctor about caffeine and supplements.

Is Celsius healthier than Monster?

For sugar and calories, Celsius (0 g sugar, 10 calories) beats original Monster (54 g sugar, 230 calories). For caffeine, Celsius is stronger per ounce. Zero-sugar Monster Ultra is a closer comparison.

Can teenagers drink Celsius?

The Celsius label says it isn’t recommended for anyone under 18.

Is Celsius OK during pregnancy?

The label says Celsius is not recommended for pregnant or nursing women. Talk to your doctor about how much caffeine is right for you.

Why do I feel sick after drinking Celsius?

Common reasons are too much caffeine, drinking it on an empty stomach, or sensitivity to the sweetener. Try a smaller amount, drink it with food, or switch to a lower-caffeine option.

Does Celsius cause a crash?

Celsius has no sugar, so there’s no sugar crash. You may still feel tired as the caffeine wears off a few hours later.

The Bottom Line

Celsius isn’t bad for most healthy adults if you keep it to one can a day and count it as part of your total caffeine. Its real downsides are the high caffeine per can, the undisclosed blend doses, the artificial sweetener and marketing that overpromises. It’s a better pick than sugary energy drinks, but people under 18, pregnant or nursing women, and anyone with heart problems or caffeine sensitivity should skip it.

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