Over-the-counter medication · Calcium Supplement / Antacid
calcium carbonate
Also sold as Tums, Caltrate, Os-Cal. This medicine treats heartburn, sour stomach, acid indigestion, and upset stomach.
Data updated 2026-05-15
- 64,404
- FDA reportsOften reported
- 1
- InteractionFew interactions
- In shortage
- FDA status
What the data shows
calcium carbonate (Tums) is an over-the-counter Calcium Supplement / Antacid, more reported than most tracked drugs (64,404 FDA reports), with 1 documented drug interaction.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
calcium carbonate (Tums) is an over-the-counter Calcium Supplement / Antacid. This medicine treats heartburn, sour stomach, acid indigestion, and upset stomach.
Calcium carbonate is a medicine that can relieve heartburn and upset stomach. It is also used as a calcium supplement.
Verify with FDA → · CMS NADAC pricing →
Drug Shortage Alert
calcium carbonate is currently listed as to be discontinued by the FDA. Affected manufacturer: Hospira, Inc., a Pfizer Company.
View all drug shortages →Drug Pricing (NADAC)
Generic Price
$0.17/unit
Generic Available
Yes (23 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats heartburn, sour stomach, acid indigestion, and upset stomach.
Common side effects
Nausea, Diarrhea, Headache
Key warnings
Do not take more than 4 tablets in 24 hours.
The sections below are summarized in plain English from calcium carbonate's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Calcium carbonate is an antacid. It works by neutralizing stomach acid. This helps to relieve heartburn and indigestion.
How to Take It
Take one to four tablets each day. Do not take more than 4 tablets in 24 hours. Do not use the highest dose for more than 2 weeks. Follow the directions on the package.
This is a plain-language summary of calcium carbonate's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Ask your doctor if it is safe to take this medicine while pregnant or breastfeeding. Calcium carbonate may pass into breast milk.
This is a plain-language summary of calcium carbonate's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. Do not take more than 4 tablets in one day.
This is a plain-language summary of calcium carbonate's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store at room temperature away from moisture and heat.
Side Effects (from patient reports)
Based on 64,404 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for calcium carbonate, by number of reports
- Feeling tired
Feeling tired
6,170 reports
- Feeling sick to your stomach
Feeling sick to your stomach
5,635 reports
- Loose stools
Loose stools
4,986 reports
- Long-term kidney problems
Long-term kidney problems
4,954 reports
- Aches or soreness
Aches or soreness
4,925 reports
- Difficulty breathing
Difficulty breathing
4,647 reports
- Throwing up
Throwing up
4,415 reports
- Pain in your head
Pain in your head
4,193 reports
- Lung infection
Lung infection
3,741 reports
- Joint pain
Joint pain
3,709 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for calcium carbonate each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where calcium carbonate sits
calcium carbonate has more FDA adverse-event reports than 78% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is calcium carbonate; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 64,404 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2002–2025.
Total Reports
64,404
Reports Mentioning Death
8,716
13.5% of reports — not proof of cause
Hospitalization Reports
27,035
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | FATIGUE | 6,169 |
| 2 | NAUSEA | 5,635 |
| 3 | DIARRHOEA | 4,987 |
| 4 | CHRONIC KIDNEY DISEASE | 4,954 |
| 5 | PAIN | 4,920 |
| 8 | DYSPNOEA | 4,648 |
| 9 | VOMITING | 4,414 |
| 10 | HEADACHE | 4,195 |
| 11 | PNEUMONIA | 3,743 |
| 12 | ACUTE KIDNEY INJURY | 3,708 |
| 13 | ARTHRALGIA | 3,708 |
| 14 | MALAISE | 3,588 |
| 15 | PYREXIA | 3,406 |
| 16 | DIZZINESS | 3,245 |
| 17 | ASTHENIA | 3,239 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Do not take more than 4 tablets in 24 hours. Do not use the maximum dosage for more than 2 weeks.
Known Drug Interactions
Drug or Drug Class Effect Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum) Phosphate binders may bind to levothyroxine. Drug or Drug Class Effect Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum) Phosphate binders may bind to levothyroxine.
Mechanism: Calcium carbonate can bind to levothyroxine in your gut, making it harder for your body to soak up the thyroid medicine.
What to do: You should separate the timing of these doses by several hours to ensure your body gets enough thyroid hormone.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
What is calcium carbonate used for?
How many tablets can I take each day?
Can I take this medicine every day?
Can I take this while pregnant?
What should I do if I miss a dose?
How should I store this medicine?
Does this medicine have side effects?
Can I take this with other medicines?
Is this the same as Tums?
Is this the same as Caltrate?
What are the common side effects of calcium carbonate?
Does calcium carbonate interact with other medications?
What drug class is calcium carbonate?
Is calcium carbonate safe during pregnancy?
Has calcium carbonate been recalled?
Is calcium carbonate currently in shortage?
Active Recalls
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
Presence of foreign substance: small metallic particles in chewable tablets.
Guardian Drug Co. Inc.
CGMP Deviations: Insanitary conditions including rodent exposure/activity in their distribution center.
GOLD STAR DISTRIBUTION INC
cGMP Deviations: Observations were made that some blister card-foils were separating from the blister cavity.
Safecor Health, LLC
Related Medications in Calcium Supplement / Antacid
Other drugs grouped near calcium carbonate - same-class peers and common alternatives.
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biotin
Vitamin B7
Dialyvite with Zinc is a prescription vitamin supplement.
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calcitriol
Rocaltrol
Calcitriol is a form of vitamin D that helps your body absorb and use calcium.
Compare with calcium carbonate →
cholecalciferol
Vitamin D3
PNV-DHA is a multivitamin with minerals and essential fatty acids.
Compare with calcium carbonate →
chromium picolinate
Chromium
Chromium picolinate is a mineral supplement.
Compare with calcium carbonate →
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What the FDA Data Shows for calcium carbonate
The FDA label for calcium carbonate (sold under brand names such as Tums, Caltrate, Os-Cal) classifies it as an over-the-counter product in the Calcium Supplement / Antacid class. This medicine treats heartburn, sour stomach, acid indigestion, and upset stomach. Official labeling lists 3 commonly reported side effects, including Nausea, Diarrhea, Headache.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 64,404 voluntary reports. The database also lists 1 documented drug interaction derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.17.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 25 recall records on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC). Shortage status: FDA Drug Shortages Database.
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 22, 2017
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages