Digestion · 8 min
Can Dogs Eat Onions? Cooked, Powder and How Much Is Toxic
Onions are toxic to dogs in every form, powder most of all, and the signs can take days to show up.
Miki RapoportCan Dogs Eat Marshmallows? The Sugar-Free Ones Are the Real Danger
Plain marshmallows are empty sugar, not poison, but sugar-free ones can contain xylitol, which is dangerous for dogs. Here is how many are OK and what to do if she ate the bag.
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A regular marshmallow won't hurt your dog. It's sugar, corn syrup and gelatin whipped full of air, about 23 calories and 4 grams of sugar in one piece, with nothing in it that's toxic to dogs. So if she snatched one off the counter while you were making s'mores, you can relax. The one to worry about is the sugar-free kind. Some sugar-free marshmallows are sweetened with xylitol, which can drop a dog's blood sugar within half an hour and damage her liver at higher amounts. That's the whole post, honestly. The rest is detail: how many is too many, what's different about minis, Peeps, Fluff and Lucky Charms, what s'mores and hot cocoa add, and what to do if she got into the bag.
Can dogs eat marshmallows at all?
Yes, a plain one now and then. It's not a good treat, just a harmless one in small amounts. Look at the bag: sugar, corn syrup, gelatin, dextrose, a little cornstarch, vanilla. Gelatin is animal protein and dogs digest it fine. The rest is sugar in different forms, about 4 grams of it in a regular marshmallow (a level teaspoon), with basically no fat or protein. Sugar isn't poison for dogs, but a dog who gets sweets often is a dog who gets heavier, and her teeth don't love it either. One marshmallow is a non-event. A marshmallow a day is a habit she doesn't need.
Why sugar-free marshmallows are the real danger
Sugar-free marshmallows are built for people on keto or low-carb diets, and to get the sweetness without sugar, some brands use xylitol. Max Mallow, a keto brand you'll see on Amazon, lists birch xylitol first in its sweetener blend, ahead of monk fruit and erythritol. Some homemade keto marshmallow recipes call for xylitol too. In a person, xylitol is just a sweetener. In a dog, it triggers a big release of insulin, and her blood sugar crashes.
The Merck Veterinary Manual puts the low blood sugar risk at about 100 mg of xylitol per kilogram of body weight, which is only 450 mg for a 10 lb dog, and says liver damage shows up in some dogs above 500 mg/kg. The blood sugar drop can start within 30 minutes. The first signs are vomiting, weakness and wobbly walking, then lethargy, and in bad cases seizures. Liver trouble can take a day or two to show, and some of those dogs never had the blood sugar dip first.
Here's the part that makes marshmallows trickier than gum: the label almost never says how much xylitol is in each piece, and Pet Poison Helpline says the amount varies widely between products. So you can't do the math at home. If she ate anything sweetened with xylitol, even a couple of minis, call your vet or a poison line right away and let them work it out. Don't wait for signs.
How many marshmallows can a dog have?
Fewer than you'd think, and only the regular sugar kind. The rule most vet nutritionists use is that treats shouldn't be more than 10% of a dog's daily calories, and that 10% covers every treat she gets, the training bits and the cheese and the last bite of your sandwich. Marshmallows have to fit inside it.
To put numbers on it, here's a typical neutered adult's daily calories (worked out with the Pet Nutrition Alliance formula), what 10% of that is, and how many regular marshmallows at 23 calories would use the whole treat budget up. The last column is the xylitol amount Merck links to low blood sugar, for the sugar-free kind.
| Dog's weight | Daily calories (about) | Treat budget (10%) | Regular marshmallows that use it all | Xylitol linked to low blood sugar |
|---|---|---|---|---|
| 10 lb | 350 kcal | 35 kcal | 1 to 2 | 450 mg |
| 20 lb | 590 kcal | 60 kcal | 2 to 3 | 900 mg |
| 50 lb | 1,160 kcal | 115 kcal | about 5 | 2,300 mg |
| 80 lb | 1,660 kcal | 165 kcal | about 7 | 3,600 mg |
Those counts are ceilings, not suggestions, since spending her whole treat allowance on sugar leaves no room for anything with food value in it. One regular marshmallow for a medium or big dog, a mini for a small one, and not every day, is a reasonable place to land.
Mini marshmallows, Peeps, Fluff and Lucky Charms
Mini marshmallows are the same recipe in a smaller piece, about 2 calories each, so one or two is close to nothing. Some vets suggest a mini for hiding a pill. They're also the easy way for a dog to eat a lot fast, since a handful goes down like nothing, so keep the bag closed.
Peeps are sugar, corn syrup and gelatin with food coloring and a wax coating. The yellow chicks' label lists 25 grams of sugar in a serving of four, so one chick is about 6 grams, more than a regular marshmallow. Nothing toxic, just a lot of sugar in a cute shape. A bite is fine; a whole tray is a stomachache.
Marshmallow Fluff is corn syrup, sugar, egg white and vanillin. No gelatin, no xylitol, so a lick off a spoon is harmless; the open jar is the problem, because a dog who gets her nose in it can put away a lot of sugar before you notice. Lucky Charms marshmallows are tiny and dyed, and the cereal has sugar as its second ingredient. A few spilled pieces won't hurt her. A bowl of it isn't a dog breakfast.
S'mores and hot cocoa: it's the chocolate, not the marshmallow
If she ate a s'more, the marshmallow and graham cracker are the least of it. Check the chocolate.
Milk chocolate has about 2.3 mg per gram, or 64 mg per ounce, of methylxanthines (theobromine plus caffeine), according to Merck Veterinary Manual's Chocolate Toxicosis entry. Semisweet and sweet dark have about 150 to 160 mg per ounce. Baking chocolate jumps to about 440 mg per ounce, cocoa powder to about 807. White chocolate has negligible amounts.
Merck puts mild signs (vomiting, diarrhea, extra thirst) at about 20 mg/kg, heart effects at 40 to 50 mg/kg, seizures at 60 mg/kg or more. Signs usually show within 6 to 12 hours.
Using Merck's numbers, a standard 1.55 oz milk chocolate bar used in s'mores holds roughly 100 mg (1.55 × 64 = 99). That's about 22 mg/kg for a 10 lb (4.5 kg) dog, right at the mild-signs line, versus about 4 mg/kg for a 50 lb dog, well below it. Darker chocolate changes that fast.
Real cocoa licked from a mug counts for far more than its marshmallows: cocoa powder is the most concentrated chocolate, about 800 mg per ounce in Merck's table. With sugar-free mix, check the sweetener for xylitol.
Dr. Renee Schmid, DVM, veterinary toxicologist and director of veterinary medicine at Pet Poison Helpline, told Rover most of the helpline's marshmallow calls involve chocolate-covered marshmallows or hot chocolate with marshmallows, rising around the winter holidays and Easter.
Thanksgiving's toasted-marshmallow sweet potato casserole is more butter and sugar than anything toxic. Onion in stuffing, fatty turkey skin and pie are bigger risks; our separate guide covers which Thanksgiving foods dogs can and can't eat.
My dog ate a bag of marshmallows. Now what?
Grab the bag. Read the ingredients.
With plain regular marshmallows, she'll probably be fine. Dr. Schmid told Rover most marshmallows aren't toxic, and Rover's guide says even a plain bag typically isn't a medical emergency. Expect a sugar-loaded dog, maybe vomiting or diarrhea in the next few hours, then normal by the next day. Keep water available. Call your vet if vomiting keeps going or she seems off. Rover says dogs with diabetes should see a vet right away after a big sugary binge.
For xylitol, chocolate-covered marshmallows or anything from a s'mores kit, call right away, not later.
ASPCA Animal Poison Control: (888) 426-4435. Pet Poison Helpline: (855) 764-7661. Both answer 24 hours and charge a fee.
Keep the bag in hand; they'll ask the brand, how many pieces are missing and roughly when she ate them.
Don't try to make her vomit at home. Merck says vomiting after xylitol should only be induced under veterinary supervision, and only while she's still normal, because blood sugar can crash fast.
Choking: a real risk for small dogs and gulpers
Marshmallows are soft, but they're also sticky, and a big one swallowed whole can lodge in a small dog's throat. Dogs that inhale food without chewing, and plenty of them do, are the ones to watch. Pawing at the mouth, gagging without bringing anything up, drooling and trouble breathing mean an emergency vet trip, not a wait-and-see. For a small dog, tear a regular marshmallow into pieces or give a mini, if you're giving one at all.
Can puppies eat marshmallows?
Skip them for puppies. Not because sugar is worse for a puppy, but because every number above works by body weight: a 5 lb puppy reaches the xylitol or chocolate line on a fraction of what a grown dog would need, and she's the one most likely to gulp a whole marshmallow and choke. A piece of her own kibble makes a better training reward anyway, and she'll be just as thrilled.
Better things to hand her instead
If you want something to hand her at the campfire so she stops staring, try a few blueberries, a slice of banana, baby carrots or a spoon of plain yogurt. Each has something in it besides sugar, and we've covered which yogurt is fine for dogs and which to leave alone. Then put the marshmallow bag, the cocoa tin and the s'mores kit somewhere she can't reach, because the dangerous versions of this treat look exactly like the harmless ones.
