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Cal-G Side Effects

Generic Name: calcium gluconate

Note: This document contains side effect information about calcium gluconate. Some of the dosage forms listed on this page may not apply to the brand name Cal-G.

For the Consumer

Applies to calcium gluconate: oral capsule, oral tablet

Other dosage forms:

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of high calcium levels like weakness, confusion, feeling tired, headache, upset stomach and throwing up, hard stools (constipation), or bone pain.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Hard stools (constipation).

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at

For Healthcare Professionals

Applies to calcium gluconate: compounding powder, injectable solution, oral tablet


Local side effects have included cutaneous calcinosis, or areas of inflammation, and subdermal hemorrhage. Extravasation of calcium gluconate (the active ingredient contained in Cal-G) can cause cellulitis.[Ref]


Gastrointestinal side effects have included nausea during infusion. They have rarely included gastric lesions and inducement of intestinal hemorrhage.[Ref]

Of five infants who received 10% calcium gluconate via an umbilical artery catheter, all five developed superficial and deep skin necrosis and clinically significant intestinal bleeding.[Ref]


Psychiatric side effects have been reported rarely. They have included a single case of mania possibly associated with changes in cerebrospinal fluid and serum calcium following calcium gluconate (the active ingredient contained in Cal-G) administration.[Ref]

A 35-year-old woman with an organic mental disorder associated with hypocalcemia and hypomagnesemia (secondary to short bowel syndrome) became noncompliant with her intramuscular injections of magnesium (Mg). Upon evaluation for progressive confusion and dysphoria, her serum Mg and calcium were found to be 0.3 mEq/L and 7.1 mg/dl, respectively. Intravenous Mg sulfate and calcium gluconate (6,000 mg) were given, with subsequent clearing of her sensorium. Within 12 hours the patient became manic and grandiose; associated Mg and calcium levels were 1.4 mEq/L and 8.2 mg/L, respectively. The symptoms of mania resolved without psychotropic medications and with discontinuation of calcium gluconate. This case report and other limited data suggest that mania can be precipitated by the rapid intravenous administration of calcium gluconate, particularly in persons who are predisposed to affective disorders.[Ref]


Genitourinary side effects have rarely included calcium nephrolithiasis. This effect has been reported more commonly with coadministration of loop diuretics.[Ref]


A 51-year-old man with no history of cardiac disease was referred for calcium gluconate (the active ingredient contained in Cal-G) pentagastrin testing for early detection of medullary thyroid carcinoma. He became pulseless and hypotensive within 15 seconds after receiving calcium gluconate 2 mg/kg and pentagastrin 0.5 mcg/kg. Atrial fibrillation and a ventricular rate response of 110/min ensued after a precordial thump. A complete evaluation for the cause of his atrial fibrillation was negative.[Ref]

Cardiovascular side effects have included peripheral vasodilation, hypotension, syncope, vasospastic angina, serious cardiac arrhythmias, AV dissociation, and shock. Extreme caution is advised when parenteral calcium is given to a patient who has received digitalis since calcium may unmask digitalis intoxication. A single case of new atrial fibrillation has been reported.[Ref]


Renal side effects have included significant increases in renal plasma flow, glomerular filtration rate, diuresis, natriuresis, and prostaglandin E2 and F1-alpha levels. However, the renal side effects do not appear to be clinically significant.[Ref]

The renal effects of calcium gluconate include significant increases in renal plasma flow, glomerular filtration rate, diuresis, natriuresis, and prostaglandin E2 and F1-alpha levels. Data indicate that calcium gluconate infusions at subpressor doses have renal vasodilating, diuretic and natriuretic properties that appear to be facilitated by an increase in the renal production of prostaglandins.[Ref]

Nervous system

Nervous system side effects have included tingling sensations, a "chalky" taste and a sense of oppression or "heat wave."[Ref]


1. Ramamurthy RS, Harris V, Pildes RS "Subcutaneous calcium deposition in the neonate associated with intravenous administration of calcium gluconate." Pediatrics 55 (1975): 802-6

2. Ravenel SD "Cellulitis from extravasation of calcium gluconate simulating osteomyelitis." Am J Dis Child 137 (1983): 402-3

3. Hironaga M, Fujigaki T, Tanaka S "Cutaneous calcinosis in a neonate following extravasation of calcium gluconate." J Am Acad Dermatol 6 (1982): 392-5

4. Book LS, Herbst JJ, Stewart D "Hazards of calcium gluconate therapy in the newborn infant: intra- arterial injection producing intestinal necrosis in rabbit ileum." J Pediatr 92 (1978): 793-7

5. Millard TP, Harris AJ, MacDonald DM "Calcinosis cutis following intravenous infusion of calcium gluconate." Br J Dermatol 140 (1999): 184-6

6. Soon SL, Chen S, Warshaw E, Caughman SW "Calcinosis cutis as a complication of parenteral calcium gluconate therapy." J Pediat 138 (2001): 778

7. Drucker D "Atrial fibrillation after administration of calcium and pentagastrin." N Engl J Med 304 (1981): 1427-8

8. Fordtran JS "Acid rebound." N Engl J Med 279 (1968): 900-5

9. Edelson GW, Kleerekoper M "Hypercalcemic crisis." Med Clin North Am 79 (1995): 79-92

10. Groat RD, Mackenzie TB "The appearance of mania following intravenous calcium replacement." J Nerv Ment Dis 168 (1980): 562-3

11. Goldsmith MA, Bhatia SS, Kanto WP Jr, Kutner MH, Rudman D "Gluconate calcium therapy and neonatal hypercalciuria." Am J Dis Child 135 (1981): 538-43

12. Ruilope LM, Oliet A, Alcazar JM, Hernandez E, Andres A, Rodicio JL, Garcia-Robles R, Martinez J, Lahera V, Romero JC "Characterization of the renal effects of an intravenous calcium gluconate infusion in normotensive volunteers." J Hypertens Suppl 7 (1989): s170-1

13. Lahera V, Ruilope LM, Romero JC "A single mechanism to explain the effect of calcium on renal function." Am J Hypertens 4 (1991): s473-81

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.