You can take up to 9 Extra Strength Tums tablets in a 24-hour period, chewing 2 to 4 tablets at a time as symptoms occur. If you’re pregnant, the limit drops to 6 tablets per day. Each Extra Strength tablet contains 750 mg of calcium carbonate (300 mg of elemental calcium), so hitting that 9-tablet maximum means you’re taking in 2,700 mg of calcium carbonate and 2,700 mg of elemental calcium in a single day.
Dosing Per Episode vs. Per Day
The per-dose recommendation is 2 to 4 tablets, chewed completely, whenever heartburn or acid indigestion hits. Most people get relief within minutes because calcium carbonate neutralizes stomach acid on contact. If symptoms return, you can take another 2 to 4 tablets, but you need to stay within that 9-tablet daily ceiling.
A practical way to think about it: if you take 3 tablets each time, you get three doses per day. If you tend to take 4 at once, you only have room for two doses before you’re at your limit.
How Tums Strengths Compare
Tums come in several strengths, and the daily maximum changes with each one because it’s based on total calcium carbonate, not the number of tablets. Regular Strength tablets are 500 mg each, with a maximum of 15 per day. Extra Strength tablets are 750 mg, capped at 9 per day. Ultra Strength tablets are 1,000 mg, with a maximum of 7.5 (effectively 7) per day. If you’ve grabbed a bottle without checking which strength you have, look at the back panel for the calcium carbonate amount per tablet.
The Two-Week Rule
Regardless of how many tablets you take per day, you should not use the maximum dosage for more than two weeks. If your heartburn keeps coming back for longer than that, the issue is likely more than occasional acid indigestion. Persistent symptoms that last beyond two weeks, especially if paired with difficulty swallowing, unintentional weight loss, persistent vomiting, or any sign of bleeding (like dark, tarry stools or vomit that looks like coffee grounds), point to something that an antacid won’t fix.
What Happens If You Take Too Many
Going over the recommended dose occasionally probably won’t cause a crisis. Few people die from an antacid overdose, and recovery is typical. But the real danger comes from chronic overuse, not a single bad day. Consistently exceeding the daily limit floods your body with calcium, which can raise blood calcium levels high enough to cause nausea, vomiting, confusion, constipation, and irregular heartbeat. Over time, excess calcium can also lead to kidney stones and permanent kidney damage.
A condition sometimes called milk-alkali syndrome can develop when high calcium intake combines with the alkaline shift that calcium carbonate creates in your blood. This raises blood pH and further impairs kidney function, creating a cycle that makes the calcium buildup worse. It’s uncommon with normal use but well-documented in people who chronically exceed the recommended dose.
Pregnancy Dosing
Heartburn is extremely common during pregnancy, which makes Tums a go-to for many expectant parents. The manufacturer sets the pregnancy limit at 6 Extra Strength tablets per day, taken 2 at a time every 4 to 6 hours as needed. Most medical guidance on pregnancy dosing refers to Regular Strength (500 mg) tablets, where the cap is 10 per day. If you’re using Extra Strength, stick with the lower tablet count on the label.
Medications That Don’t Mix Well
Calcium carbonate interferes with how your body absorbs a surprisingly long list of medications. Thyroid medication, certain antibiotics, iron supplements, seizure medications, and some cholesterol drugs all have reduced effectiveness when taken alongside Tums. If you take any prescription medication, leave at least a two-hour gap before or after chewing a Tums tablet. This is especially important for thyroid hormones, which are very sensitive to calcium interference.
Why Tums Work Fast but Don’t Last
Tums neutralize acid directly in the stomach rather than blocking acid production the way other heartburn medications do. That’s why relief comes within minutes. The tradeoff is that the effect is short-lived, typically lasting 30 to 60 minutes, because your stomach continues producing acid. If you find yourself reaching for Tums multiple times a day on a regular basis, a different class of medication that reduces acid production over a longer period is likely a better fit for your situation.