Health Guide

Calcium supplement (Oral route, parenteral route)

Brand Names:

  • Ascocid
  • Cal-C-Caps
  • Cal-G
  • Cal-Lac
  • Citracal
  • PhosLo
  • Posture
  • Prelief
  • Rolaids
  • Alka-Seltzer Relief Chews - Heartburn
  • Calcium Antacid Extra Strength
  • Calcium Stanley
  • Citracal Gummies
  • Citracal Slow Release
  • Sound Body Calcium Antacid Extra Strength - Assorted Fruit Flavors
  • Sound Body Calcium Antacid Ultra Strength - Assorted Berry Flavors
  • Up & Up Calcium Antacid Extra Strength - Assorted Berries
  • Up & Up Calcium Antacid Regular Strength - Assorted Fruit Flavor
  • Up & Up Calcium Antacid Regular Strength - Peppermint

Dosage Forms:

  • Powder for Suspension
  • Tablet, Chewable
  • Tablet
  • Capsule, Liquid Filled
  • Capsule
  • Powder
  • Tablet, Effervescent
  • Syrup
  • Wafer
  • Suspension
  • Tablet, Extended Release
  • Granule

Uses of This Medicine:

Calcium supplements are taken by individuals who are unable to get enough calcium in their regular diet or who have a need for more calcium. They are used to prevent or treat several conditions that may cause hypocalcemia (not enough calcium in the blood). The body needs calcium to make strong bones. Calcium is also needed for the heart, muscles, and nervous system to work properly.

The bones serve as a storage site for the body's calcium. They are continuously giving up calcium to the bloodstream and then replacing it as the body's need for calcium changes from day to day. When there is not enough calcium in the blood to be used by the heart and other organs, your body will take the needed calcium from the bones. When you eat foods rich in calcium, the calcium will be restored to the bones and the balance between your blood and bones will be maintained.

Pregnant women, nursing mothers, children, and adolescents may need more calcium than they normally get from eating calcium-rich foods. Adult women may take calcium supplements to help prevent a bone disease called osteoporosis. Osteoporosis, which causes thin, porous, easily broken bones, may occur in women after menopause, but may sometimes occur in elderly men also. Osteoporosis in women past menopause is thought to be caused by a reduced amount of ovarian estrogen (a female hormone). However, a diet low in calcium for many years, especially in the younger adult years, may add to the risk of developing it. Other bone diseases in children and adults are also treated with calcium supplements.

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

A calcium "salt" contains calcium along with another substance, such as carbonate or gluconate. Some calcium salts have more calcium (elemental calcium) than others. For example, the amount of calcium in calcium carbonate is greater than that in calcium gluconate. To give you an idea of how different calcium supplements vary in calcium content, the following chart explains how many tablets of each type of supplement will provide 1000 milligrams of elemental calcium. When you look for a calcium supplement, be sure the number of milligrams on the label refers to the amount of elemental calcium, and not to the strength of each tablet.

Calcium supplementStrength of each tablet (in milligrams [mg])Amount of elemental calcium per tablet (in milligrams)Number of tablets to provide 1000 milligrams of calcium
Calcium carbonate625

Calcium citrate9502005
Calcium gluconate500

Calcium lactate325
Calcium phosphate, dibasic5001159
Calcium phosphate, tribasic800

Injectable calcium is administered only by or under the supervision of your health care professional. Other forms of calcium are available without a prescription.

For good health, it is important that you eat a balanced and varied diet. Follow carefully any diet program your health care professional may recommend. For your specific dietary vitamin and/or mineral needs, ask your health care professional for a list of appropriate foods. If you think that you are not getting enough vitamins and/or minerals in your diet, you may choose to take a dietary supplement.

The daily amount of calcium needed is defined in several different ways.

  • Recommended Dietary Allowances (RDAs) are the amount of vitamins and minerals needed to provide for adequate nutrition in most healthy persons. RDAs for a given nutrient may vary depending on a person's age, sex, and physical condition (e.g., pregnancy).
  • Daily Values (DVs) are used on food and dietary supplement labels to indicate the percent of the recommended daily amount of each nutrient that a serving provides. DV replaces the previous designation of United States Recommended Daily Allowances (USRDAs).
  • Recommended Nutrient Intakes (RNIs) are used to determine the amounts of vitamins, minerals, and protein needed to provide adequate nutrition and lessen the risk of chronic disease.

Normal daily recommended intakes in milligrams (mg) for calcium are generally defined as follows:

PersonsU.S. (mg)Canada (mg)
Infants birth to 3 years of age400 to 800250 to 550
Children 4 to 6 years of age800600
Children 7 to 10 years of age800700 to 1100
Adolescent and adult males800 to 1200800 to 1100
Adolescent and adult females800 to 1200700 to 1100
Pregnant females12001200 to 1500
Breast-feeding females12001200 to 1500

Getting the proper amount of calcium in the diet every day and participating in weight-bearing exercise (walking, dancing, bicycling, aerobics, jogging), especially during the early years of life (up to about 35 years of age) is most important in helping to build and maintain bones as dense as possible to prevent the development of osteoporosis in later life.

The following table includes some calcium-rich foods. The calcium content of these foods can supply the daily RDA or RNI for calcium if the foods are eaten regularly in sufficient amounts.

Food (amount)Milligrams (mg) of calcium
Nonfat dry milk, reconstituted (1 cup)375
Lowfat, skim, or whole milk (1 cup)290 to 300
Yogurt (1 cup)275 to 400
Sardines with bones (3 ounces)370
Ricotta cheese, part skim (½ cup)340
Salmon, canned, with bones (3 ounces)285
Cheese, Swiss (1 ounce)272
Cheese, cheddar (1 ounce)204
Cheese, American (1 ounce)174
Cottage cheese, lowfat (1 cup)154
Tofu (4 ounces)154
Shrimp (1 cup)147
Ice milk (¾ cup)132

Vitamin D helps prevent calcium loss from your bones. It is sometimes called "the sunshine vitamin" because it is made in your skin when you are exposed to sunlight. If you get outside in the sunlight every day for 15 to 30 minutes, you should get all the vitamin D you need. However, in northern locations in winter, the sunlight may be too weak to make vitamin D in the skin. Vitamin D may also be obtained from your diet or from multivitamin preparations. Most milk is fortified with vitamin D.

Do not use bonemeal or dolomite as a source of calcium. The Food and Drug Administration has issued warnings that bonemeal and dolomite could be dangerous because these products may contain lead.

Before Using This Medicine:

If you are taking a dietary supplement without a prescription, carefully read and follow any precautions on the label. For these supplements, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Problems in children have not been reported with intake of normal daily recommended amounts. Injectable forms of calcium should not be given to children because of the risk of irritating the injection site.

Older adults—

Problems in older adults have not been reported with intake of normal daily recommended amounts. It is important that older people continue to receive enough calcium in their daily diets. However, some older people may need to take extra calcium or larger doses because they do not absorb calcium as well as younger people. Check with your health care professional if you have any questions about the amount of calcium you should be taking in each day.


It is especially important that you are receiving enough calcium when you become pregnant and that you continue to receive the right amount of calcium throughout your pregnancy. The healthy growth and development of the fetus depend on a steady supply of nutrients from the mother. However, taking large amounts of a dietary supplement during pregnancy may be harmful to the mother and/or fetus and should be avoided.


It is especially important that you receive the right amount of calcium so that your baby will also get the calcium needed to grow properly. However, taking large amounts of a dietary supplement while breast-feeding may be harmful to the mother and/or baby and should be avoided.

Other medicines—

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these dietary supplements, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using dietary supplements in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Altretamine
  • Amygdalin
  • Dasabuvir
  • Deferoxamine
  • Digoxin
  • Dimercaprol
  • Eltrombopag
  • Elvitegravir
  • Gefitinib
  • Ketoconazole
  • Ledipasvir
  • Levomethadyl
  • Licorice
  • Mefenamic Acid
  • Mycophenolate Mofetil
  • Mycophenolic Acid
  • Pazopanib
  • Phenytoin
  • Quinine
  • Raltegravir
  • Rilpivirine
  • Sodium Polystyrene Sulfonate
  • Vismodegib

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems—

The presence of other medical problems may affect the use of dietary supplements in this class. Make sure you tell your doctor if you have any other medical problems, especially:

  • Diarrhea or
  • Stomach or intestinal problems—Extra calcium or specific calcium preparations may be necessary in these conditions.
  • Heart disease—Calcium by injection may increase the chance of irregular heartbeat.
  • Hypercalcemia (too much calcium in the blood) or
  • Hypercalciuria (too much calcium in the urine)—Calcium supplements may make these conditions worse.
  • Hyperparathyroidism or
  • Sarcoidosis—Calcium supplements may increase the chance of hypercalcemia (too much calcium in the blood).
  • Hypoparathyroidism—Use of calcium phosphate may cause high blood levels of phosphorus which could increase the chance of side effects.
  • Kidney disease or stones—Too much calcium may increase the chance of kidney stones.

Proper Use of This Medicine:

Drink a full glass (8 ounces) of water or juice when taking a calcium supplement. However, if you are taking calcium carbonate as a phosphate binder in kidney dialysis, it is not necessary to drink a glass of water.

This dietary supplement is best taken 1 to 1½ hours after meals, unless otherwise directed by your health care professional. However, patients with a condition known as achlorhydria may not absorb calcium supplements on an empty stomach and should take them with meals.

For individuals taking the chewable tablet form of this dietary supplement:

  • Chew the tablets completely before swallowing.

For individuals taking the syrup form of this dietary supplement:

  • Take the syrup before meals. This will allow the dietary supplement to work faster.
  • Mix in water or fruit juice for infants or children.

Take this dietary supplement only as directed. Do not take more of it and do not take it more often than recommended on the label. To do so may increase the chance of side effects.


The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (capsules, chewable tablets, lozenges, oral solution, oral suspension, syrup, tablets, extended-release tablets, tablets for solution):
    • To prevent deficiency, the amount taken by mouth is based on normal daily recommended intakes (Note that the normal daily recommended intakes are expressed as an actual amount of calcium. The salt form [e.g., calcium carbonate, calcium gluconate, etc.] has a different strength):
      • Adults and teenagers—800 to 1200 milligrams (mg) per day.
      • Pregnant and breast-feeding females—1200 mg per day.
      • Children 4 to 10 years of age—800 mg per day.
      • Children birth to 3 years of age—400 to 800 mg per day.
      • Adults and teenagers—800 to 1100 mg per day.
      • Adult and teenage females—700 to 1100 mg per day.
      • Pregnant and breast-feeding females—1200 to 1500 mg per day.
      • Children 7 to 10 years of age—700 to 1100 mg per day.
      • Children 4 to 6 years of age—600 mg per day.
      • Children birth to 3 years of age—250 to 550 mg per day.
    • To treat deficiency:
      • Adults, teenagers, and children—Treatment dose is determined by prescriber for each individual based on severity of deficiency.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Keep out of the reach of children.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Do not keep outdated medicine or medicine no longer needed.

Precautions While Using This Medicine:

If this dietary supplement has been ordered for you by your health care professional and you will be taking it in large doses or for a long time, your health care professional should check your progress at regular visits. This is to make sure the calcium is working properly and does not cause unwanted effects.

Do not take calcium supplements within 1 to 2 hours of taking other medicine by mouth. To do so may keep the other medicine from working properly.

Unless you are otherwise directed by your health care professional, to make sure that calcium is used properly by your body:

  • Do not take other medicines or dietary supplements containing large amounts of calcium, phosphates, magnesium, or vitamin D unless your health care professional has told you to do so or approved.
  • Do not take calcium supplements within 1 to 2 hours of eating large amounts of fiber-containing foods, such as bran and whole-grain cereals or breads, especially if you are being treated for hypocalcemia (not enough calcium in your blood).
  • Do not drink large amounts of alcohol or caffeine-containing beverages (usually more than 8 cups of coffee a day), or use tobacco.

Some calcium carbonate tablets have been shown to break up too slowly in the stomach to be properly absorbed into the body. If the calcium carbonate tablets you purchase are not specifically labeled as being "USP," check with your pharmacist. He or she may be able to help you determine which tablets are best.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Although the following side effects occur very rarely when the calcium supplement is taken as recommended, they may be more likely to occur if it is taken in large doses, if it is taken for a long time or if it is taken by patients with kidney disease.

Check with your doctor as soon as possible if any of the following side effects occur:

More common
(For injection form only)
flushing and/or sensation of warmth or heat
irregular heartbeat
nausea or vomiting
skin redness, rash, pain, or burning at injection site
tingling sensation
Difficult or painful urination
nausea or vomiting (continuing)
Early signs of overdose
Constipation (severe)
dryness of mouth
headache (continuing)
increased thirst
loss of appetite
mental depression
metallic taste
unusual tiredness or weakness
Late signs of overdose
drowsiness (severe)
high blood pressure
increased sensitivity of eyes or skin to light
irregular, fast, or slow heartbeat
unusually large amount of urine or increased frequency of urination

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 9/4/2017
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