Like other sulfonylureas, chlorpropamide acts to increase the secretion of insulin, so it is only effective in patients who have some pancreatic beta cell function.

The risk of hypoglycemia makes this drug a poor choice for the elderly and patients with mild to moderate hepatic and renal impairment.

[1] Chlorpropamide and other sulfonylureas encourage weight gain, so they are generally not favored for use in very obese patients.

[1][2] The most common side effects are skin related, such as rashes, photoallergy and (in rare cases) Stevens–Johnson syndrome.

[1] Less common side effects of chlorpropamide include gastrointestinal symptoms such as nausea, vomiting, and diarrhea.