Calcium carbonate: uses, side effects, and dosage

Anyone who isn’t getting enough calcium and or is at increased risk for developing osteoporosis may benefit from taking a calcium supplement (Kantor, 2016; Li, 2018). 

In addition to restoring calcium levels in people with a calcium deficiency, calcium carbonate can be used to alleviate heartburn and help balance blood mineral levels in people with chronic kidney disease (Fritz, 2021). 

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Calcium is critical for maintaining strong bone density and supporting nerve and muscle function. Most people get all the calcium they need from their diet, thanks to calcium-rich foods like milk and cheese, but some people may need a supplement (Wallace, 2014). 

Calcium carbonate is one such supplement. It’s available as a pill, chewable tablet, and powder. 

Most people get all the calcium they need from their diet. For those who need more, adding calcium-rich foods to your daily routine can be effective. 

Calcium is most commonly found in dairy products like milk, yogurt, and cheese. You can also get calcium from dark leafy vegetables (like broccoli and kale), grains, and legumes (Institute of Medicine, 2011).

Adults should get about 1,000 mg of calcium every day. Women over the age of 50 should get about 1,300 mg of calcium daily. If you’ve been diagnosed low calcium levels, your healthcare provider may recommend adding a dietary supplement like calcium carbonate to your regimen.

Calcium carbonate is a form of calcium used to treat a wide range of conditions including the ones below.

Calcium deficiency

There are estimates that as many as 40% of Americans don’t get their daily recommended intake of calcium (Drake, 2018). 

Getting enough calcium is one of the best ways to support bone health and reduce the risk of osteoporosis. However, the amount of calcium your body absorbs changes over your lifetime. As infants, we absorb about 60% of the calcium we take in. By the time we’re adults, we only absorb about 25% (Cosman, 2014). 

That percentage continues to decrease as we age, which is why health professionals often recommend that older adults adopt a calcium-rich diet. If that’s not enough, you might need to add a supplement to your regimen. 

Since vitamin D facilitates the absorption of calcium from your digestive system, many providers recommend using a combination supplement that contains calcium and vitamin D. Many multivitamins have both, making them a convenient option for many people. 

Calcium deficiency is common in people with a wide range of underlying health conditions. These include:

• Hypothyroidism

• Hypoparathyroidism (low levels of parathyroid hormone)

• Kidney disease

Certain medications also affect calcium absorption so a supplement may be recommended to prevent low calcium levels. These medications include (Fritz, 2021):

• Certain anti-seizure medications

• Bisphosphonates

• Calcitonin

• Chloroquine

• Corticosteroids

• Loop diuretics (water pills)

• Plicamycin

• Rifampin

Acid reflux 

Calcium carbonate (brand name Tums) can be used to alleviate the burning sensation that comes from acid reflux. The acid in our stomachs is important for breaking down the food we eat, but if it escapes up into the esophagus (the tube that connects your mouth to your stomach), it can cause pain and damage. 

While occasional heartburn, like after a big meal, is normal, persistent heartburn often requires treatment. Calcium carbonate can be used to alleviate the symptoms of heartburn because it neutralizes the acid.

As an antacid, calcium carbonate may be recommended for people with (Fritz, 2021):

• GERD (gastroesophageal reflux disease), the persistent return of acid from the stomach into the esophagus

• Stomach ulcers from chronic use of certain common pain medications (NSAIDs) 

• Indigestion (abdominal pain after eating)

Chronic kidney disease

People who live with chronic kidney disease sometimes develop a condition called hyperphosphatemia, or high blood phosphate levels. Calcium carbonate can be used as a phosphate binder to help reduce the amount of phosphate in the body.

Since calcium carbonate is typically taken on a short-term basis or in small doses, side effects are minimal. With excessively high doses, though, you may experience:

• Abdominal pain or bloating

• Confusion

• Constipation

• Gallstones 

• Headache

• Irregular heart rhythms

• Kidney stones

• Muscle twitching

• Stomach pain

• Nausea

• Vomiting

In extreme cases, high calcium levels can be dangerous and even deadly, but taking a calcium supplement typically won’t cause dangerously high calcium levels in your blood. Instead, excessive use of calcium supplements can cause kidney damage because your kidneys are responsible for filtering the calcium out of your blood. 

If you or someone you know has consumed too much calcium carbonate, consult with a healthcare professional.

To understand how much calcium carbonate you should take, consult with your healthcare provider. The daily recommended amount depends on your age, medical history, and any underlying conditions you may have. For example, the range recommended dosages for adults include (Fritz, 2021):

• 1,000 mg to 7,000 mg for heartburn

• 1,000 mg to 1,200 mg for low calcium

• 1,500 mg to 3,000 mg for high blood potassium levels in people with kidney disease

The U.S. Food and Drug Administration (FDA) recommends 1,000 mg for healthy adults under age 50. Women older than 50 should increase their calcium intake to 1,200 mg daily; men can wait until age 70 to up theirs (Plantz, 2021).

Why the difference? Bone loss is a natural part of aging, but it begins earlier for women during menopause. Taking the daily recommended amount of calcium won’t prevent bone loss, but it does slow the progression (Institute of Medicine, 2011). 

When determining an appropriate dosage of calcium carbonate, it’s good to understand how much calcium you already get from your diet. Factors that affect how much calcium your body can absorb include age, weight, stomach acidity, estrogen, and vitamin D levels (Fritz, 2021).

There are different types of calcium supplements. Calcium carbonate is often recommended for people who need to get more calcium in their diet. That’s because unlike calcium citrate, which needs to be taken on an empty stomach, calcium carbonate is absorbed well when taken with food. Calcium carbonate supplements are also less expensive than calcium citrate.

For people with a calcium deficiency who are also taking antacids like omeprazole or pantoprazole, calcium citrate may be a better option. This is because calcium citrate is absorbed more effectively when taken with these medications. 

If you’re considering calcium carbonate supplements, talk to a healthcare provider first. Tell them about your medical history, especially if any of the following apply (Fritz, 2021; Plantz, 2021):

• Pregnancy: While calcium carbonate is generally safe for pregnant or breastfeeding people with acid reflux, your healthcare provider may want to monitor your use.

• Medication: Some medications can have adverse effects when mixed with calcium supplements. Examples include bisphosphonates, fluoroquinolones, tetracyclines, thyroid hormone replacement medications, proton pump inhibitors, and anti-arrhythmic drugs.

• Kidney problems: If you have kidney disease or a risk of kidney stones.

While taking calcium carbonate, always follow the instructions provided. It’s usually recommended that you take calcium carbonate with food and water, due to how it reacts in the acidic environment of the stomach (Fritz, 2021).

Informing your health provider of any other medications you’re taking can help avoid any negative drug interactions. Because of the way calcium carbonate interacts with stomach acid, it may affect how some drugs are absorbed.

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Current version

February 09, 2022

Written by

Amelia Willson

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.