The federal department says taking lithium carries a risk of high blood calcium, or hypercalcemia, and is sometimes associated with a hormone disorder known as hyperparathyroidism.
Lithium is used widely to treat mania associated with bipolar disorder. Available in Canada for more than 60 years, the medication is used to treat acute manic episodes and as a long-term therapy to reduce their frequency and severity.
Lithium therapy may cause high levels of calcium in the bloodstream, which may or may not be accompanied by an increased level of parathormone, causing hyperparathyroidism.
While in many cases the effects of high blood calcium and/or parathormone are unnoticeable or mild, in severe cases they can be life-threatening, Health Canada said Wednesday in an advisory. Severe hypercalcemia can cause coma and cardiac arrest.
Health Canada is working with pharmaceutical companies to update product labels for lithium drugs to include new warnings about the risk of hypercalcemia and hyperparathyroidism, and the need to consider calcium monitoring before and during therapy.
There are currently seven lithium-containing medications available in Canada: Apo-Lithium Carbonate, Carbolith, Lithane, Lithmax, Phl-Lithium Carbonate, Pms-Lithium Carbonate and Pms-Lithium Citrate.
Consumers taking lithium who have questions or concerns should speak to their health provider, Health Canada advises.
"Tell your doctor if you experience symptoms of hypercalcemia, which include fatigue, depression, mental confusion, nausea, vomiting, excessive thirst, appetite loss, abdominal pain, frequent urination, muscle and joint aches, and muscle weakness.
"Do not stop lithium treatment unless you have discussed the benefits and the risks of your treatment with your doctor."