Cortisone isn’t inherently bad for you, but it carries real risks that scale with how much you take and how long you take it. A single injection or a short course of oral steroids is generally safe for most people. The problems start when cortisone is used repeatedly, at high doses, or over long stretches of time. Understanding where those thresholds lie can help you weigh the tradeoffs.
How Cortisone Works in Your Body
Cortisone is a synthetic version of cortisol, the stress hormone your adrenal glands produce naturally. When you take cortisone, it enters your cells and binds to a receptor that travels into the nucleus, where it dials down the production of inflammatory proteins. It also blocks the production of compounds called prostaglandins and leukotrienes, which are directly involved in pain and swelling. This is why cortisone can feel almost miraculous for conditions like inflamed joints, allergic reactions, or autoimmune flares.
The catch is that this same anti-inflammatory power suppresses parts of your immune system broadly, not just at the site of the problem. Cortisone doesn’t distinguish between harmful inflammation and the normal immune surveillance your body relies on to fight infections and heal tissue. The longer it’s active in your system, the more those secondary effects accumulate.
Short-Term Use Is Usually Low Risk
A brief course of oral cortisone, lasting less than three to four weeks, poses relatively little danger for most people. At that duration, your body’s own cortisol production hasn’t had time to shut down, so you can typically stop the medication without tapering. The side effects people notice during short courses tend to be temporary: trouble sleeping, mood swings, increased appetite, mild fluid retention, and a jittery or wired feeling. These usually resolve within days of stopping.
That said, even short-term use can spike blood sugar significantly. In people with well-controlled type 2 diabetes, blood glucose after a single steroid injection can peak anywhere from 165 to 500 mg/dL, with average peaks around 300 mg/dL. Those levels typically return to baseline within a few days, but in the first one to three days after a dose, glucose can swing unpredictably. If you have diabetes or prediabetes, monitoring closely during that window matters.
Long-Term Use Is Where Serious Risks Emerge
When cortisone is taken continuously for more than a few weeks, the risk profile changes substantially. Your adrenal glands, sensing all the synthetic cortisol in your bloodstream, begin producing less of their own. After roughly three to four weeks of daily use, this suppression becomes significant enough that stopping abruptly can leave your body unable to mount a normal stress response. This is why long-term users need to taper their dose gradually rather than quit cold turkey.
Bone loss is one of the most well-documented consequences of extended use. Fracture risk increases as early as three to six months after starting treatment. At doses equivalent to 7.5 mg or more of prednisone per day, the risk of spinal fractures jumps fivefold, and hip fracture risk more than doubles. Even the first 90 days show a dose-dependent rise in fracture risk, meaning higher cumulative doses correlate with greater danger. This bone thinning happens because cortisone triggers the death of bone cells and interferes with calcium absorption.
Other long-term effects include thinning skin that bruises easily, weight gain concentrated around the midsection and face, elevated blood pressure, muscle weakness, and increased susceptibility to infections. Prolonged use also raises the risk of cataracts and can elevate eye pressure. About 5% to 6% of people exposed to steroids experience a significant rise in eye pressure, which, if unmonitored, can progress toward glaucoma.
Cortisone Injections and Joint Health
Joint injections are one of the most common uses of cortisone, and many people assume that because the drug is delivered locally, it carries fewer systemic risks. That’s partly true, but the local effects on cartilage and surrounding tissue deserve attention.
Data from the Osteoarthritis Initiative found that patients who received cortisone injections in the knee had 3.2 times higher odds of their osteoarthritis progressing on X-rays compared to those who didn’t get injections. For patients who received continuous injections, that number climbed to 4.67 times higher odds. In the hip, 44% of patients who received injections showed measurable narrowing of the joint space within about six months. Cortisone triggers the death of bone cells near the injection site, which reduces blood supply to the bone and weakens it. In some cases, this leads to rapid joint destruction or small fractures in the bone just beneath the cartilage.
Tendons are vulnerable too. Cortisone decreases collagen production locally, which can limit healing and increase the chance of a tear or rupture. Studies in animal models show that even injections placed near a tendon (not directly into it) can weaken the tendon and reduce its elasticity. For surgical outcomes, the data is striking: receiving a cortisone injection within six months before rotator cuff repair, or getting more than two injections within a year before surgery, nearly doubled the rate of poor outcomes. Patients with tennis elbow who had three or more injections before surgery were 3.5 times more likely to need a revision procedure.
How Many Injections Are Too Many
There is no universally agreed-upon limit for how many cortisone injections you can safely receive in a single joint. Guidelines from major pain and orthopedic societies recommend a minimum interval of two to three weeks between repeat injections, with most practitioners preferring to wait at least three months. No clearly defined yearly or lifetime caps exist, which means the decision is typically made on a case-by-case basis.
The practical guidance most orthopedic surgeons follow is to stop the series of injections once pain relief has plateaued or is no longer improving. If a joint stops responding to cortisone, continuing to inject it only adds risk without adding benefit. For weight-bearing joints like hips and knees, many clinicians become cautious after three to four injections per year, given the cartilage data.
Who Faces the Highest Risk
Certain groups are more vulnerable to cortisone’s downsides. People with diabetes face unpredictable blood sugar spikes that can persist for up to three weeks after an injection. People with osteoporosis or low bone density are at compounded risk, since cortisone accelerates the exact process they’re already fighting. Those with glaucoma or a family history of it face a higher chance of dangerous eye pressure increases.
Age plays a role as well. Older adults metabolize steroids more slowly and have less bone density to spare. Children and adolescents on long-term steroids can experience growth suppression. And anyone already on medications that thin the blood or suppress the immune system may see those effects amplified.
When Cortisone Makes Sense
For acute, intense inflammation, cortisone remains one of the most effective tools available. A single injection into a painfully swollen knee can restore mobility in days. A short burst of oral steroids can halt a severe asthma flare or an allergic reaction that isn’t responding to other treatments. In autoimmune diseases where the immune system is actively destroying tissue, cortisone can be the difference between organ damage and stability while slower-acting medications take effect.
The risk-benefit math tilts in cortisone’s favor when the inflammation is severe, the duration of use is short, and there’s a clear plan for transitioning to other treatments. It tilts against cortisone when it’s being used as a long-term maintenance strategy, when injections are repeated frequently into the same joint without clear benefit, or when safer alternatives haven’t been tried first. Cortisone is a powerful tool with a narrow window where it works best, and the problems most people worry about come from using it outside that window.