8 mins read

Calcium supplements are taken to increase calcium levels. Common side effects include constipation, gas, and feeling bloated. Before taking a calcium supplement, talk with your health care provider about all of your health conditions and any medicines you are taking. Calcium supplements come in several salts and forms. Ask your health care provider if you are not sure whether you need a calcium supplement or which one to take.

Uses

What are calcium supplements used for?

Calcium supplements are commonly taken as a dietary supplement to increase your calcium levels. 

Calcium supplements may also be used for other conditions as determined by your health care provider.

How do calcium supplements work (mechanism of action)?

Calcium supplements work by increasing your body’s calcium levels.

Calcium is a mineral. Your body uses calcium for important functions related to your bones, teeth, blood vessels, muscles, nerves, blood clotting, and hormones. Calcium is found in many types of foods. The amount of calcium you should get every day is known as the recommended dietary allowance (RDA). The amount of calcium you need depends on your age and sex. If you are not sure how much calcium you need or whether you should take a calcium supplement, ask your health care provider.

What forms of calcium are typically used as supplements?

  • Calcium carbonate
  • Calcium citrate
  • Calcium gluconate
  • Calcium lactate
  • Oyster shell calcium

Calcium supplements are commonly found in products that also contain other ingredients, such as vitamin D or multivitamins.

Some calcium forms are used as antacids. See Calcium Antacids for more information.

How should I store calcium supplements?

Storage requirements may vary among calcium supplements. Calcium supplements should generally be stored at room temperature, between about 68 F and 77 F (20 C and 25 C). Do not freeze them. Storage requirements for some calcium supplements may not be provided with the product. If you are not sure how to store your calcium supplement, ask your pharmacist.

Side Effects

What are the most common side effects of calcium supplements?

The most common side effects of calcium supplements are listed below. Tell your health care provider if you have any of these side effects that bother you.

There may be other side effects of calcium supplements that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of calcium supplements?

While less common, the most serious side effects of calcium supplements are described below, along with what to do if they happen.

Severe Allergic Reactions. Calcium supplements may cause allergic reactions, which can be serious. Stop taking calcium supplements and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

High Calcium Levels (Hypercalcemia). Calcium supplements may rarely cause high calcium levels, also called hypercalcemia. Your risk may be higher if you have been taking calcium supplements for a long time, at high doses, or if you have certain medical conditions. Hypercalcemia can lead to serious problems with your kidneys, heart, or bones. Stop taking calcium supplements and call your health care provider if you have any of the following symptoms.

  • Peeing frequently
  • Feeling thirsty
  • Tiredness
  • Confusion or dizziness
  • Poor appetite
  • Nausea or vomiting
  • Constipation
  • Muscle weakness
  • Bone pain
  • Abnormal heart rhythm

Kidney Stones. Calcium supplements might increase the risk of kidney stones, especially if you have had kidney stones before. Drinking plenty of water can help prevent kidney stones. Tell your health care provider right away if you feel severe pain in your side or back or have blood in your urine (pee). Your pee may look pink, red, or brown.

Warnings & Precautions

Who should not use calcium supplements?

Allergies to Ingredients. People who are allergic to any of the following should not take calcium supplements.

  • Calcium
  • Caltrate
  • Citracal
  • Os-Cal
  • Oysco
  • Oyster shell calcium
  • Rolaids
  • Tums
  • Viactiv
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific calcium supplements they stock.

What should I know about calcium supplements before using them?

Calcium supplements come in many salts and dosage forms. Some calcium supplements may be better absorbed than others. Some may be better tolerated than others. If you are not sure whether you need a calcium supplement or which one you should take, ask your pharmacist or other health care provider. Tell all of your health care providers if you start taking a calcium supplement.

People who smoke tobacco, drink a lot of caffeine, or have low stomach acid levels (more common if you are 65 or older) may have trouble absorbing calcium. If any of these apply to you, talk to your health care provider about which calcium supplement you should take and how you should take it. This will help make sure you are getting what you need.

Read and follow the instructions for the calcium supplement you have and make sure you understand how to take it properly. The label will tell you the amount of calcium in the supplement, which can vary by product. Do not take more than the recommended dose.

For best absorption, take no more than a dose of 500 milligrams (mg) of calcium at one time from calcium supplements. Your pharmacist can explain how much calcium you will get from a specific product and whether it is better to divide your doses throughout the day.

You need vitamin D to absorb calcium. Follow any instructions from your health care provider about your diet or vitamin D supplements to make sure your body can absorb your calcium supplement. 

Keep calcium supplements out of the reach of children.

If you have gas, constipation, or bloating with calcium supplements, talk with your health care provider about ways to limit these side effects. It might help to take your calcium supplement with meals, take a different calcium supplement, or take lower doses more often throughout the day.

Calcium supplements may affect how other medicines work. You may need to take a calcium supplement at a different time than other medicines. Your health care provider can let you know when to take each medicine.

If you are taking a liquid calcium supplement, check the label to see if you need to shake it. Some liquid calcium supplements may need to be shaken well before you measure your dose. Use an accurate measuring device to measure your liquid calcium supplement dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist what measuring device to use.

If you are taking a chewable calcium supplement, be sure to chew it well before swallowing it. Follow the directions on the product label and ask your pharmacist if you are not sure how to take it.

If you have phenylketonuria (PKU), check the ingredients in calcium supplement labels before taking one. Some chewable calcium supplements may contain phenylalanine, which can be dangerous for people with PKU. Ask your pharmacist if you need help finding a calcium supplement that is safe for you to take.

What should I tell my health care provider before using calcium supplements?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if calcium supplements are right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Low-Calcium Diet. Tell your health care provider if you are on a low-calcium diet. Your health care provider will let you know if you should take a calcium supplement if you have dietary restrictions.

Other Medicines and Supplements. Calcium supplements may interact with other medicines and supplements. Before taking calcium supplements, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. The recommended daily allowance (RDA) for calcium does not change during pregnancy. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take a calcium supplement while you are pregnant or trying to get pregnant.

Breastfeeding. The recommended daily allowance (RDA) for calcium intake does not change while you are breastfeeding. Calcium from calcium supplements passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take a calcium supplement while breastfeeding.

Interactions

Do calcium supplements interact with foods or drinks?

Some calcium supplements, such as calcium carbonate, should be taken with food to help improve absorption. Some calcium supplements, such as calcium citrate, may be taken with food or on an empty stomach. Ask your pharmacist or other health care provider if you are not sure how to take your calcium supplement.

Heavy drinking may make it harder for your body to absorb calcium. It is best to limit the amount of alcohol you drink.

Do calcium supplements interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking calcium supplements.

  • Bictegravir (found in Biktarvy), dolutegravir (found in Dovato, Tivicay, and others), elvitegravir (found in Genvoya or Stribild), or raltegravir (Isentress), which are medicines used for HIV
  • A thyroid medicine, such as levothyroxine, which is used to raise thyroid hormone levels
  • Lithium, which is a medicine used for certain mental health conditions
  • A fluoroquinolone, such as ciprofloxacin (Cipro, Cipro XR, Porquin), levofloxacin, moxifloxacin, or ofloxacin, which is a medicine used to treat certain infections
  • A bisphosphonate, such as alendronate (Binosto, Fosamax), ibandronate, or risedronate (Actonel, Atelvia), which is a medicine commonly used for osteoporosis
  • A tetracycline, such as doxycycline, minocycline, omadacycline (Nuzyra), sarecycline (Seysara), or tetracycline, which is a medicine used to treat infections or other conditions
  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure

Calcium supplements may affect the absorption of many other medicines. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with calcium supplements. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally take too much of a calcium supplement?

If you or someone else has taken too many calcium supplements, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of calcium supplements?

Take your calcium supplement as directed on the product label or as your health care provider recommends. If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.