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Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Generic drug name: calcium
Brand name(s): CALCITONE
GENERIC: not available FAMILY: Dietary Supplements
Find the drug label by searching at DailyMed.

Generic drug name: calcium carbonate (KAL see um CAR boe nate)
GENERIC: available FAMILY: Minerals
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Generic drug name: calcium citrate (KAL see um SI trate)
GENERIC: available FAMILY: Minerals
Find the drug label by searching at DailyMed.

Generic drug name: calcium gluconate (KAL see um GLUE ko nate)
Brand name(s):
GENERIC: available FAMILY: Minerals
Find the drug label by searching at DailyMed.

Generic drug name: calcium lactate (KAL see um LAK tate)
Brand name(s):
GENERIC: available FAMILY: Minerals
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Minerals taken at the level that supplies normal body needs (not megadoses) do not pose a risk to the fetus or the nursing infant.

Facts About This Drug [top]



Milk, liquid or powdered, including low-fat and nonfat milk, low-fat yogurt, ice cream, cheese (some are high in fat and/or cholesterol), canned salmon and sardines, shellfish, broccoli, green leafy vegetables.
1 cup plain low-fat yogurt 415 milligrams (mg) calcium
1 cup milk 300 mg calcium
3 ½ ounces canned salmon with bones 198 mg calcium

Calcium is a mineral that is...



Milk, liquid or powdered, including low-fat and nonfat milk, low-fat yogurt, ice cream, cheese (some are high in fat and/or cholesterol), canned salmon and sardines, shellfish, broccoli, green leafy vegetables.
1 cup plain low-fat yogurt 415 milligrams (mg) calcium
1 cup milk 300 mg calcium
3 ½ ounces canned salmon with bones 198 mg calcium

Calcium is a mineral that is stored in the bones and is necessary for bone growth and strength. It also benefits the nervous system, muscles and heart. As your body ages, its ability to absorb calcium decreases, even though its need for calcium does not diminish. If you are older and also have a diet that lacks adequate calcium, both factors limit the amount of the mineral available for your body to use.

Calcium deficiency in older adults causes changes in the bones called osteomalacia and osteoporosis. Osteomalacia is an overall decrease in bone density. Osteoporosis (which occurs most frequently in thin, small-boned or white women) is a condition in which the bones become so weak that they are more likely to break or become deformed.

Getting the right amount of calcium

How much calcium do you need? The recommended dietary allowance (RDA) for calcium is 1,200 milligrams (mg) per day for men and women over the age of 50. Public Citizen thinks that this is a safe and desirable intake for all adults. It will not necessarily protect patients against the fractures and deformity of osteoporosis, but it may help and is unlikely to do any harm. We do not recommend taking more than 1,500 mg per day, since the greater amount has no advantages and can cause some dangerous adverse effects (see "Adverse Effects" section on this page).

The best way to get calcium is to eat foods that are rich in it (see “Foods High in Calcium” box at the top of this page). In particular, you can increase your calcium intake by drinking milk and adding liquid or powdered milk to almost any cooked food (you can use low-fat or nonfat milk if you want to keep your fat intake down). If you cannot get enough calcium from your diet (e.g., eating yogurt), take a calcium supplement. However, if you have a history of kidney stones, do not increase your calcium intake without talking with your doctor first.

Side effects

Britain's Expert Group on Vitamins and Minerals concluded that:

In humans, the main adverse effect associated with high levels of calcium intake is milk-alkali syndrome (MAS), resulting in hypercalcaemia [increased calcium in the blood], alkalosis and renal impairment. Symptoms can include abdominal pain, hypertension, headaches and tissue calcification. The condition has been reported in a small number of subjects taking calcium-containing medication. Previously, MAS was more common in males taking absorbable alkali and milk, but is now more common in females taking calcium-containing medication Doses up to 1,500 mg/day supplemental calcium would not be expected to result in any adverse effect, but higher doses could result in adverse gastrointestinal symptoms in a few people. An estimate for total calcium intakes has not been made as the effect is related to calcium in supplemental doses.[1]

A July 2011 article in The American Journal of Clinical Nutrition examined information from the Women’s Health Initiative randomized clinical trial and stated that patients taking calcium carbonate plus vitamin D showed an increase in the incidence of self-reported urinary tract stones. However, according to the article, the occurrence in urinary tract stones was small between the groups and less than 10 percent of the women were hospitalized. [2]Many women take calcium supplements that are available over the counter and should be aware of this possible risk.

In March 2013, Prescrire International published an article regarding calcium supplements and the risk of cardiovascular events. Some of the data presented in the article showed an increased cardiovascular risk observed in patients taking calcium supplements, while other data showed no increased cardiovascular risk in such patients.  Based on these conflicting results, calcium supplementation should be used with caution.[3]

Calcium for the prevention of osteoporosis

Many people, particularly women, take calcium supplements in the hope that it will decrease their risk of getting osteoporosis. While it has been shown that a diet containing adequate calcium can prevent high blood pressure, taking supplements to prevent osteoporosis is controversial. If you want to reduce your risk of osteoporosis, try quitting smoking, drinking alcohol in moderation if at all and doing weight-bearing exercise such as walking, aerobics, jogging, dancing, tennis or biking (although biking is less beneficial than the other listed activities).

Before buying a calcium supplement

If you decide to take a calcium supplement, some cautions are in order. You should not take calcium supplements that contain bonemeal or dolomite. The Food and Drug Administration reported that these ingredients might contain lead in amounts that could present a risk to older adults.[4] Furthermore, the body does not absorb all calcium supplements with equal ease. Unfortunately, it has not been determined which supplement is absorbed the best. One study showed that calcium citrate was best absorbed, but another showed that there was no significant difference in absorption among various types of supplements.[4],[5] Ask your pharmacist or other health professional for suggestions.

When comparing calcium supplements, you should always check how much elemental (pure) calcium they contain. Because calcium supplements contain other ingredients in addition to calcium, a 100-mg calcium supplement tablet does not contain 100 mg of calcium, and a 100-mg tablet of one supplement does not necessarily have the same amount of calcium as a 100-mg tablet of another. Calcium carbonate is 40 percent calcium, calcium gluconate is 9 percent calcium and calcium citrate is 24 percent calcium. Read the label on the container to find out the amount of elemental calcium. This is the only measurement that counts as far as your body is concerned.

A recent Journal of Parenteral and Enteral Nutrition (JPEN) systematic review revealed that, with a few possible exceptions, dietary supplements offer no benefits to well-nourished adults eating a Western diet and, in many cases, may be harmful. The results of this study reinforce Worst Pills, Best Pills News’ longstanding view that there is little evidence that dietary supplements are either safe or effective.

The study authors concluded that with the possible exception of vitamin D in elderly patients and omega-3 fatty acids in patients with a history of cardiovascular disease, no data support the widespread use of dietary supplements in the U.S. and other Western countries. Indeed, the data suggest that certain commonly used dietary supplements, including beta-carotene, vitamin A and vitamin E, may be harmful. We agree.[6]

Before You Use This Drug [top]

Do not use if you have or have had:

  • high level of calcium in your blood
  • high level of calcium in your urine
  • calcium kidney stones
  • sarcoidosis

Tell your doctor if you have or have had:

  • allergies to drugs
  • pregnancy or are breast-feeding
  • dehydrated
  • electrolyte imbalance
  • diarrhea
  • chronic malabsorption
  • kidney stones
  • kidney disease
  • low or no stomach acid (for calcium carbonate only)

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Have regular doctor visits if taking large doses or for a long period of time.
  • After taking a calcium supplement, wait one to two hours before taking any other drug by mouth.
  • Avoid taking this drug along with other preparations containing significant amounts of calcium, phosphate, magnesium, or vitamin D unless your doctor advises you to do so.
  • Avoid taking this drug along with certain fiber-containing foods such as bran and whole-grain breads and cereals; wait one to two hours before or after taking calcium.
  • For calcium carbonate: Take one to one and a half hours after meals.
  • Avoid excessive use of alcohol, tobacco, or caffeine.
  • Use only calcium products labeled “USP” (calcium carbonate)

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for the next dose. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Take with a full glass (eight ounces) of water or juice (all dosage forms).
  • For chewable tablets: chew tablets well before swallowing.
  • Store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

ACHROMYCIN, AGENERASE, amprenavir, aspirin, ACTONEL, CALAN SR, CHIBROXIN, chlorothiazide, CILOXAN, CIPRO, ciprofloxacin, COVERA-HS, DIURIL, ECOTRIN, enoxacin, FLOXIN, GENUINE BAYER ASPIRIN, ISOPTIN SR, LEVAQUIN, levofloxacin, lomefloxacin, MAXAQUIN, norfloxacin, NOROXIN, OCUFLOX, ofloxacin, PANMYCIN, PENETREX, risedronate, SKELID, sparfloxacin, SUMYCIN, tetracycline, tiludronate, trovafloxacin, TROVAN, verapamil, VERELAN, ZAGAM.

Adverse Effects [top]

Call your doctor immediately if you experience:

  • drowsiness
  • continuing nausea and vomiting
  • weakness
  • difficult or painful urination

Early symptoms of too much calcium:

  • severe constipation
  • dry mouth
  • continuing headache
  • continuing increased thirst
  • irritability
  • appetite loss
  • mental depression
  • metallic taste
  • unusual tiredness or weakness

Late symptoms of too much calcium:

  • confusion
  • drowsiness
  • high blood pressure
  • increased sensitivity of eyes or skin to light
  • irregular, slow, or fast heartbeat
  • nausea or vomiting
  • increased amount of urine or frequency of urination

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  • blood pressure
  • blood and urine calcium levels
  • electrocardiogram (ECG or EKG)
  • magnesium blood test
  • parathyroid blood test
  • phosphate blood test
  • potassium blood test
  • kidney function test

last reviewed November 30, 2022