Is Monster Bad for You? Sugar, Caffeine and Zero Ultra Explained

Monster Energy is one of the biggest energy drinks in the world, and its 16 oz cans are bigger than a Red Bull’s. Many people drink one every morning – or several during a long shift. But is Monster bad for you? The two big issues are sugar and caffeine, and the “Zero” versions only fix one of them.

The short answer: an occasional Monster isn’t dangerous for a healthy adult, but it’s not good for you. A regular 16 oz can has 54 g of sugar – more than a whole day’s limit – plus 160 mg of caffeine. Daily cans add up to a lot of empty calories, and several cans a day can cause a racing heart, anxiety and bad sleep. Monster Zero Ultra has no sugar, but the same caffeine and sweeteners.

What’s in a can of Monster

Monster Energy (original green, 16 oz), according to Open Food Facts:

Ingredients: carbonated water, sugar, glucose, citric acid, natural flavors, taurine, sodium citrate, color added, panax ginseng extract, L-carnitine L-tartrate, caffeine, sorbic acid (preservative), benzoic acid (preservative), niacinamide (vitamin B3), sucralose, salt, D-glucuronolactone, inositol, guarana extract, vitamins B6, B2 and B12, maltodextrin.

Per can (16 oz)	Monster Energy	Monster Zero Ultra
Calories	230	about 10
Sugar	54 g	0 g
Caffeine	160 mg	about 150 mg
Sodium	370 mg	380 mg
Sweeteners	Sugar, glucose, sucralose	Erythritol, sucralose
Preservatives	Sorbic acid, benzoic acid	Sorbic acid, benzoic acid

Zero Ultra: Open Food Facts.

The sugar problem

54 g of sugar is about 13 teaspoons. The American Heart Association advises no more than 25 g of added sugar a day for women and 36 g for men (Johnson et al., Circulation, 2009) – one Monster goes over both.

Sugary drinks are one of the easiest ways to gain weight, because liquid calories don’t fill you up. In a large analysis, people who drank 1–2 sugary drinks a day had a 26% higher risk of type 2 diabetes than people who drank them rarely (Malik et al., Diabetes Care, 2010). A daily Monster also adds about 1,600 calories a week – almost half a pound of body fat if you don’t cut calories somewhere else.

The caffeine: how much is too much?

A 16 oz Monster has 160 mg of caffeine (from caffeine and guarana) – about 1.5–2 cups of coffee.

Who	Safe caffeine	Monster cans
Healthy adults	Up to 400 mg a day	2 cans = 320 mg
Pregnant or breastfeeding	Up to 200 mg a day	1 can is almost the limit
Children and teens	Energy drinks not advised	0

Limits from the FDA, EFSA and the American Academy of Pediatrics.

Too much caffeine can cause a fast or uneven heartbeat, jitters, anxiety, headaches, stomach upset and poor sleep. Caffeine lasts for hours, so a can after lunch can still affect your sleep at night – and bad sleep makes you reach for another can the next day.

What about your heart?

In a small trial, 18 healthy young adults drank 32 oz of an energy drink (two 16 oz cans) on one day and the same caffeine in another drink on another day. After the energy drink, their heart rhythm changed a bit more (a longer QT interval) and their blood pressure stayed higher for longer (Fletcher et al., Journal of the American Heart Association, 2017). The changes were small, but they suggest energy drinks may affect the heart more than caffeine alone. Doctors have reported heart rhythm problems in people who drank several cans, often together with alcohol or hard exercise. If you have a heart condition, skip energy drinks.

Is Monster Zero Ultra better?

Yes – but not by as much as the white can suggests.

• Better: 0 g sugar and about 10 calories instead of 230.
• The same: about 150 mg of caffeine, plus taurine and other stimulant extras.
• Sweeteners: erythritol and sucralose. People with high blood levels of erythritol had more heart attacks and strokes in a 2023 study, and in lab tests it made blood clot more easily (Witkowski et al., Nature Medicine, 2023). Sucralose and acesulfame K were linked to more coronary heart disease in the French NutriNet-Santé study (Debras et al., BMJ, 2022). These are links, not proof.

Both versions also use sorbic acid and benzoic acid as preservatives. They’re approved, but the NutriSmart app gives both its highest risk rating. Read why in our articles on potassium sorbate and sodium benzoate.

How much Monster is safe?

How much	What we think
Now and then	Fine for most healthy adults
1 can a day	Too much sugar if it’s regular Monster; Zero is better
2+ cans a day	Too much caffeine once you add coffee or tea
With alcohol	Avoid – caffeine hides how drunk you feel

Tips if you drink Monster:

1. Switch to Zero Ultra or a smaller can to cut the sugar.
2. One can, before 2 pm.
3. Count all your caffeine – coffee, tea, pre-workout and soda too.
4. Drink water alongside it, especially if you work out.
5. Try a slower swap: coffee, cold brew or green tea give you caffeine without sugar or sweeteners. See our guide to the healthiest energy drink.

See what’s in your energy drink before you buy it. With NutriSmart, you photograph the label or scan the barcode. The app shows the sugar per can, lists the sweeteners, preservatives and colors, explains the risks of each one and gives the drink a health score out of 100. Set an alert for sucralose, and the app warns you every time a product you scan contains it.Get the app free

You can also read whether Celsius is bad for you and our guide to artificial sweeteners.

The bottom line

A regular Monster isn’t dangerous once in a while for a healthy adult, but it’s not healthy: a 16 oz can has 54 g of sugar and 160 mg of caffeine. Zero Ultra removes the sugar but keeps the caffeine and adds sweeteners. Limit yourself to one can on the days you really need it, never mix it with alcohol, and skip it completely if you’re a teen, pregnant or have heart problems.