Glucagon seldom causes side effects, according to the U.S. Food and Drug Administration (FDA). Nausea or vomiting occasionally occurs. Some patients have generalized allergic reactions such as low blood pressure (hypotension), respiratory distress or urticaria (hives).

More severe side effects may indicate an overdose of glucagon. They include:

• Vomiting or diarrhea, which may cause dehydration
• Hypokalemia (insufficient potassium)
• Temporary elevation of blood pressure and pulse, which according to the FDA may need to be treated in patients with coronary artery disease or pheochromocytoma (an adrenal tumor)

Patients are advised to seek immediate medical care if they display these symptoms.