How many calories are in Tums?

About 5 per Regular Strength tablet, or 10 per two-tablet dose, from dextrose and maltodextrin. Extra Strength tablets are similar.

Do Tums break ketosis?

No. A two-tablet dose has about 2 g of carbohydrate, too little to affect ketosis.

Can I take Tums on an empty stomach?

Yes, as an antacid they work whenever heartburn starts. If you take them as a calcium supplement, calcium carbonate is absorbed better with food.

Why do I get heartburn when fasting?

Coffee and acidic drinks on an empty stomach can trigger it in some people. If it happens often, talk to your doctor before relying on antacids.

Do Tums Break a Fast? No

Reviewed by the FastTrack team · Updated June 2026

Short answer: No

Tums barely touch a fast. Two Regular Strength tablets have about 10 calories, mostly from dextrose and maltodextrin, too little to matter for weight loss or ketosis. They are a medicine, so take them as the label or your doctor directs.

Calories	~5 kcal per tablet
Breaks a weight-loss fast?	No
Breaks ketosis?	No
Breaks autophagy?	Unlikely
Insulin impact	Minimal

Why a dose of Tums is not a meal

The active ingredient is calcium carbonate, a mineral salt with no calories that neutralizes stomach acid. Each Regular Strength tablet has 500 mg of it, providing 200 mg of calcium. The calories come from the chewable base, which includes dextrose and maltodextrin. A usual dose of 2 to 4 tablets adds roughly 10 to 20 calories, a small amount that does not end a weight-loss fast.

Heartburn while fasting and medicine timing

Coffee or acidic drinks on an empty stomach bring on heartburn for some people, and Tums can help now and then; sugar-free versions use sorbitol and sucralose. The label caps Regular Strength at 15 tablets in 24 hours, or 10 during pregnancy, and the maximum dose for no more than two weeks unless a doctor advises it. Antacids can interact with some prescription drugs, so ask a pharmacist about timing. Heartburn on most days needs a doctor's visit.

How much is safe

Take Tums as the label or your doctor directs, whenever you need them; there is no reason to delay a dose to protect a fast. If you use them often, the sugar-free version keeps the calories closer to zero.

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Frequently asked questions

How many calories are in Tums?: About 5 per Regular Strength tablet, or 10 per two-tablet dose, from dextrose and maltodextrin. Extra Strength tablets are similar.
Do Tums break ketosis?: No. A two-tablet dose has about 2 g of carbohydrate, too little to affect ketosis.
Can I take Tums on an empty stomach?: Yes, as an antacid they work whenever heartburn starts. If you take them as a calcium supplement, calcium carbonate is absorbed better with food.
Why do I get heartburn when fasting?: Coffee and acidic drinks on an empty stomach can trigger it in some people. If it happens often, talk to your doctor before relying on antacids.