Most cortisone shot side effects are short-lived, resolving within a few days. The most common one, a temporary pain flare at the injection site, typically fades within 48 hours. Other side effects have their own timelines, ranging from a day or two for sleep disruption to several months for changes in skin or soft tissue beneath the injection site.
The Post-Injection Pain Flare
The side effect you’re most likely to experience is a flare of pain, swelling, and irritation right at the injection site. This happens because the steroid solution itself can temporarily irritate the joint lining before the medication’s anti-inflammatory effects kick in. The flare typically lasts up to two days. Icing the area and resting the joint during this window usually helps. If you’re still feeling significantly worse after 48 hours, that’s worth a call to your provider.
Facial Flushing
About 40% of people who get a cortisone injection into a joint experience facial flushing, a warm redness that spreads across the face and upper chest. It can feel alarming if you’re not expecting it, but it resolves on its own, typically within three days. It’s a systemic reaction to the steroid entering the bloodstream in small amounts, not a sign of an allergic reaction.
Sleep Disruption and Mood Changes
Cortisone can cause a jittery, wired feeling similar to drinking too much coffee. This is especially common in people around age 65 and older, though it can happen at any age. The insomnia and restlessness typically last one to three days after the injection. Some people also notice mild mood changes, like feeling anxious or irritable, during this same window.
Blood Sugar Spikes
If you have type 2 diabetes, a single cortisone shot can push your blood sugar noticeably higher. In people with well-controlled diabetes, blood glucose levels can peak anywhere from 165 to 500 mg/dL within the first two to 84 hours after the injection. Levels generally return to baseline somewhere between 18 hours and 21 days later, though most people see normalization within the first week. If you’re diabetic, plan to monitor your blood sugar more frequently for a few days after your shot and talk to your provider about adjusting your management plan during that period.
Menstrual Cycle Disruption
Roughly half of premenopausal women experience some change to their menstrual cycle after a cortisone injection. In a study of 77 women, the disruptions varied: some had their next period arrive earlier than expected (by a median of nine days), while others had it arrive later (by a median of seven days). About a quarter of the women reported changes in flow, mostly heavier bleeding or a longer period. These changes generally affected only one or two cycles before the pattern returned to normal.
Skin and Soft Tissue Changes
This is the side effect with the longest timeline. Cortisone can cause the fat and soft tissue beneath the skin near the injection site to thin out, creating a visible dip or lightening of the skin. These changes don’t appear immediately. They typically show up one to four months after the injection. The good news is that this effect is usually reversible, but recovery is slow, taking anywhere from 6 to 30 months for the tissue to fill back in. Injections closer to the skin surface, like those in tendons or smaller joints in the hands, carry a higher risk of this side effect than deeper joint injections in the knee or hip.
Tendon Weakening
Repeated cortisone injections can weaken tendons over time, which is one reason providers limit how often you can get shots in the same area. The concern is greatest in weight-bearing tendons like the Achilles or the rotator cuff. After an injection near a tendon, most providers recommend avoiding heavy loading or intense exercise for a period to reduce rupture risk. This isn’t a side effect you’ll feel, which makes it easy to ignore, but it’s one of the main reasons cortisone shots aren’t meant to be a long-term, repeated solution.
When a Side Effect Isn’t Just a Side Effect
A normal post-injection flare involves mild to moderate soreness that improves steadily over 48 hours. A joint infection, while rare, looks very different: severe pain that comes on fast and keeps getting worse, a joint that’s hot and swollen, skin that changes color over the area, and sometimes a fever. If your symptoms are intensifying rather than fading after the first couple of days, or if you develop a fever at any point, that warrants urgent medical attention. Joint infections progress quickly and need treatment right away to prevent lasting damage.