Cortisone shots are not universally bad, but they carry real risks that often get downplayed in a quick doctor’s visit. The concerns fall into several categories: they can damage tendons, spike blood sugar, suppress your body’s natural hormone production, cause painful flare-ups, and in many cases, perform no better than a simple saline injection over the long term. Here’s what you should know before agreeing to one.
They Can Weaken and Tear Tendons
This is one of the most serious risks. Corticosteroids break down collagen, the protein that gives tendons their strength. In human Achilles tendons, researchers have documented collagen disorganization and tissue death after steroid injections. Animal studies show measurable decreases in tensile force, meaning the tendon literally becomes weaker and less able to handle load.
The numbers for rotator cuff injuries are striking. A cohort study of over 1,000 patients found that those who received steroid injections had a 9.8% rate of rotator cuff tears, compared to just 1.2% in patients who didn’t get injections. After adjusting for other risk factors, the injection group was roughly 7.4 times more likely to tear a rotator cuff tendon. These tears didn’t happen immediately. The average time between the injection and the tear was about 39 months, meaning the damage accumulates quietly over years.
Blood Sugar Spikes Can Be Dramatic
If you have type 2 diabetes, a single cortisone shot can send your blood sugar on a roller coaster. Even in patients with well-controlled diabetes, blood glucose levels after an injection have been recorded peaking anywhere from 165 to 500 mg/dL. Two studies found mean peaks around 320 mg/dL, well above the normal range. Those peaks can hit as soon as 2 hours after the injection or take up to 84 hours to appear, and glucose levels can take anywhere from 18 hours to 21 days to return to baseline.
That’s a wide and unpredictable range. For someone carefully managing their diabetes with insulin or medication, a sudden spike that lasts potentially weeks can be genuinely dangerous. Many patients aren’t warned about this ahead of time or told to monitor their blood sugar more closely after the shot.
Your Body’s Cortisol Production Shuts Down
Your adrenal glands naturally produce cortisol, a hormone essential for energy, stress response, blood pressure regulation, and immune function. When you inject a synthetic version into a joint, your body detects the flood of steroid and dials back its own production. This is called adrenal suppression, and the Endocrine Society flags it as a concern for up to two months after a single joint injection.
During that window, you may feel unusually fatigued, lightheaded, or generally unwell, especially during physical stress or illness. Your body is temporarily less equipped to mount a normal stress response. For people getting repeated injections or receiving them in multiple joints, the suppression can overlap and compound.
Post-Injection Flares Are Common
A cortisone flare is a burst of increased pain and inflammation at the injection site, typically worse than the original problem. It usually shows up 48 to 72 hours after the shot and can last several days. Reported incidence rates vary wildly depending on the study and the injection site, ranging from 1% to as high as 81%. For shoulder injections specifically, one clinical study found that roughly 1 in 3 patients experienced a flare reaction.
This means a significant number of people walk out of the office expecting relief and instead get days of intensified pain before any benefit kicks in. It’s temporary, but it’s worth knowing about before you’re blindsided by it.
Long-Term Pain Relief May Be No Better Than Placebo
Perhaps the most compelling argument against routine cortisone shots is how they perform over time compared to doing nothing special at all. A systematic review published in the British Journal of Sports Medicine pooled data from 11 randomized controlled trials involving 1,353 patients with hip osteoarthritis. The finding: none of the injectable treatments, including corticosteroids, showed significant improvement in pain or function compared to a simple saline injection at either the 2-to-4 month or 6-month mark.
Both groups improved from their starting point, which tells you something important. The act of getting an injection itself, plus the natural fluctuation of symptoms over time, accounts for most of the improvement people feel. The steroid component doesn’t appear to add meaningful benefit beyond a few weeks in many cases. You’re accepting real biological risks for what may largely be a placebo effect.
Practical Limits on Frequency
There’s no formal maximum number of cortisone shots defined by medical guidelines. The American Academy of Orthopaedic Surgeons notes that the frequency depends on individual circumstances. In practice, most doctors set a working limit of 3 to 4 injections per year in a single joint. Beyond that threshold, the pain relief tends to diminish with each successive shot while the risks of infection, tendon damage, and other complications continue to rise.
If you’ve already had several rounds of injections without lasting improvement, that’s a signal the underlying problem needs a different approach. Repeated shots into the same joint aren’t a long-term management strategy. They’re a short-term tool that loses effectiveness and gains risk with each use.
When the Risks Might Still Be Worth It
None of this means cortisone shots are never appropriate. For someone in acute, severe pain who needs short-term relief to start physical therapy or get through a critical period, the brief anti-inflammatory effect can serve a real purpose. The problems arise when injections become a recurring default, when patients aren’t informed about the trade-offs, or when the shot is treating a condition where it’s unlikely to outperform simpler options.
The key is going in with realistic expectations. A cortisone shot is not a fix. It’s a temporary suppression of inflammation that comes with measurable costs to your tendons, your endocrine system, and potentially your blood sugar. For many people, especially those considering their third or fourth injection, the math stops adding up.