Steroid injections are one of the most common pain treatments in medicine, and most people tolerate them well. But they do carry real side effects, ranging from a temporary pain flare at the injection site to blood sugar spikes, skin changes, and mood disruption. The risks increase with higher doses and more frequent injections, so understanding what to expect helps you weigh the benefits against the downsides.
Pain Flare at the Injection Site
The most common immediate reaction is a “cortisone flare,” a burst of pain and swelling in the hours after the injection that can feel worse than what brought you in. This happens when the injected steroid crystals irritate the surrounding tissue. It typically peaks within the first 24 to 48 hours and settles on its own. Ice and over-the-counter pain relief usually manage it. The flare is not a sign that something went wrong, and it doesn’t predict whether the injection will ultimately help.
Blood Sugar Spikes
Steroid injections can raise blood sugar significantly, even from a single shot into a joint. In people with well-controlled type 2 diabetes, blood glucose levels can climb to anywhere between 165 and 500 mg/dL within hours of the injection, with most studies finding average peaks around 300 to 320 mg/dL. That’s well above the normal range and high enough to cause symptoms like increased thirst, fatigue, and blurry vision.
The spike is temporary but unpredictable in duration. Some people return to baseline within 18 hours, while others see elevated readings for up to three weeks. The biggest jumps tend to happen in the first one to three days. If you have diabetes, plan to monitor your blood sugar more frequently for about five days after the injection. People without diabetes can also experience a mild, short-lived rise, though it rarely causes noticeable symptoms.
Skin and Tissue Changes Near the Injection Site
Steroid injections can cause visible changes in the skin and tissue where the needle goes in. The two most common are lightening of the skin (hypopigmentation) and a dent or dimple from localized fat loss beneath the surface. Skin lightening occurs in roughly 1 to 6 percent of patients, and fat atrophy has a wider reported range of about 1.5 to 40 percent depending on the injection location and dose.
These changes typically appear one to four months after the injection. In about half of cases, the area fills back in and the skin color normalizes over several months, with the recovery timeline loosely tied to how much steroid was used. Most cases resolve within six to 24 months. In rare instances, the changes are permanent and may require cosmetic treatment like fat grafting. These effects are most noticeable in people with darker skin tones and in areas where the injection is close to the surface, such as the wrist or elbow.
Mood Changes, Insomnia, and Anxiety
Even a localized steroid injection sends some of the drug into your bloodstream, and that systemic absorption can affect your brain. Reported reactions include irritability, mood swings, anxiety, difficulty sleeping, and in some cases euphoria or depressed mood. Severe psychiatric reactions, including mania or psychotic symptoms, occur in an estimated 5 to 6 percent of people receiving corticosteroids, though this figure comes largely from studies of higher systemic doses rather than single joint injections.
These symptoms typically show up within a few days to a couple of weeks. Most people recover once the steroid clears the system or after a dose reduction. There is no reliable way to predict who will experience mood effects, though higher doses appear to carry greater risk. If you’ve had a strong emotional reaction to steroids before, that history is worth mentioning before your next injection.
Menstrual and Hormonal Disruption
Steroid injections can disrupt menstrual cycles and cause unexpected vaginal bleeding. A Kaiser Permanente study found that postmenopausal women who received a corticosteroid injection for joint or back pain were more than twice as likely to report abnormal bleeding compared to similar women who did not get an injection (17 percent versus 7 percent). This association held even after accounting for body weight and hormone use. Among premenopausal women, the difference was not statistically significant, though irregular periods are still commonly reported anecdotally after steroid shots.
Cartilage Damage and Tendon Weakening
Repeated steroid injections into the same joint can damage cartilage over time. This is one of the main reasons clinicians limit how often they’ll inject a given joint. The steroid reduces inflammation in the short term but may accelerate the breakdown of the cartilage cushion, potentially worsening the underlying condition the injection was meant to treat.
Tendons are also vulnerable. Corticosteroids can weaken tendon fibers, raising the risk of partial tears or complete rupture. This is a particular concern for weight-bearing tendons like the Achilles or the rotator cuff tendons in the shoulder. The risk increases with repeated injections to the same area.
Joint Infection
Any time a needle enters a joint, there is a small chance of introducing bacteria. The resulting condition, septic arthritis, is serious but very rare. Recent data puts the infection rate at 0.002 to 0.008 percent following steroid injections. Risk factors include older age, diabetes, and already being on systemic steroid therapy. Signs of infection, such as a hot, swollen, increasingly painful joint with fever developing in the days after an injection, warrant urgent medical attention.
Risks Specific to Spinal Injections
Epidural steroid injections, used for back and nerve pain, carry a few additional risks beyond what joint injections do. The needle passes close to the spinal cord’s protective membrane, and if it punctures that membrane (called a dural puncture), it can cause a distinctive positional headache that worsens when you sit or stand and improves when you lie flat. Unintentional dural puncture happens in roughly 0.5 to 1.5 percent of epidural procedures, and 50 to 80 percent of those patients go on to develop a headache. Most resolve within days, but some require a follow-up procedure called a blood patch to seal the puncture.
How Often You Can Safely Get Them
There is no universally agreed-upon limit on how many steroid injections you can receive. A large survey of orthopedic surgeons found wide variability in practice, with no clearly defined yearly or lifetime caps. Most clinicians use a minimum interval of about three months between repeat injections in the same joint, though guidelines from several pain medicine societies suggest the minimum gap could be as short as two to three weeks depending on the situation.
The key principle is that injections should not be given on a fixed schedule. Each subsequent shot should be based on how you responded to the last one and whether your pain has actually returned. If an injection provides little or no relief, repeating it is unlikely to help and only adds cumulative risk. Routine series of injections without reassessment are specifically discouraged in current guidelines.