Calcium gluconate is the calcium salt of gluconic acid and is used as a mineral supplement and medication.[1] As a medication it is used by injection into a vein to treat low blood calcium, high blood potassium, and magnesium toxicity.[1][2] Supplementation is generally only required when there is not enough calcium in the diet.[3] Supplementation may be done to treat or prevent osteoporosis or rickets.[1] It can also be taken by mouth but is not recommended for injection into a muscle.[1] Side effects when injected include slow heart rate, pain at the site of injection, and low blood pressure.[3] When taken by mouth side effects may include constipation and nausea.[1] Blood calcium levels should be measured when used and extra care should be taken in those with a history of kidney stones.[3] At normal doses, use is regarded as safe in pregnancy and breastfeeding.[1][4] Calcium gluconate is made by mixing gluconic acid with calcium carbonate or calcium hydroxide.[5] Calcium gluconate came into medical use in the 1920s.[6] It is on the World Health Organization's List of Essential Medicines.[7] Calcium gluconate is available as a generic medication.[2][8] It is closely related to calcium borogluconate, which is commonly used in veterinary medicine owning to its higher solubility. [9] It is used for intravenous administration of calcium, notably in ruminants