Calcium gluconate is a mineral supplement. It is manufactured by the neutralization of gluconic acid with lime or calcium carbonate.
It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system

Medical uses
Hypocalcemia
10% calcium gluconate solution (given intravenously) is the form of calcium most widely used in the treatment of hypocalcemia. This form of calcium is not as well absorbed as calcium lactate, and it only contains 0.93% (930 mg/dl) calcium ion (defined by 1 g weight solute dissolved in 100 ml solvent to make 1% solution w/v). Therefore, if the hypocalcaemia is acute and severe, calcium chloride is given instead.

Magnesium sulfate overdose
It is also used to counteract an overdose of Epsom Salts magnesium sulfate,[3] which is often administered to pregnant women in order to prophylactically prevent seizures (as in a patient experiencing preeclampsia). Magnesium sulfate is no longer given to pregnant women who are experiencing premature labor in order to slow or stop their contractions (other tocolytics are now used instead due to better efficacy and side effect profiles). Excess magnesium sulfate results in magnesium sulfate toxicity, which results in both respiratory depression and a loss of deep tendon reflexes (hyporeflexia). Calcium gluconate is the antidote for magnesium sulfate toxicity.

HF burns
Gel preparations of calcium gluconate are used to treat hydrofluoric acid burns.This is because calcium gluconate reacts with hydrofluoric acid to form insoluble, non-toxic calcium fluoride.

Hyperkalemia
Calcium gluconate is also used as a cardioprotective agent in hyperkalemia. Though it does not have an effect on potassium levels in the blood, it reduces the excitability of cardiomyocytes thus lowering the likelihood of developing cardiac arrhythmias.

Side effects
Calcium gluconate side effects include nausea, constipation, upset stomach. Rapid intravenous injections of calcium gluconate may cause hypercalcaemia, which can result in vasodilation, cardiac arrhythmias, decreased blood pressure, and bradycardia. Extravasation of calcium gluconate can lead to cellulitis. Intramuscular injections may lead to local necrosis and abscess formation.
It is also reported that this form of calcium increases renal plasma flow, diuresis, natriuresis, glomerular filtration rate,and prostaglandin E2 and F1-alpha levels.