Common side effects of a cortisone injection include elevated blood sugar and facial flushing, according to About.com. Other potential side effects include pain, infection, changes in the skin's pigment, loss of fatty tissue and tendon rupture.
Facial flushing and elevated blood sugar are considered systematic side effects, which means the side effects affect the entire body rather than just the injection site, states About.com. Elevated blood sugar is a side effect that often occurs in those with diabetes, and it is important that those who have diabetes monitor blood sugar levels following a cortisone injection. Facial flushing is seen in about 15 percent of all patients and occurs more commonly in women than men.
Local side effects occur around the site of the injection and are rare, explains About.com. Of these pain is one of the more common ones and sometimes lasts for 24 to 48 hours. For people who have dark complexions, cortisone sometimes cause the skin to lighten. This is a cosmetic change with no other harm associated.
High doses of cortisone have some potentially detrimental effects on tissues of the body, claims About.com. When the cortisone is injected into fatty areas, a condition called fat atrophy sometimes occurs. This condition causes the loss of fatty tissue, which lead to dimpled skin or thinning of fat in some cases.