Most people start feeling meaningful pain relief from a cortisone shot within two to five days, though some notice improvement within hours due to the local anesthetic that is typically mixed in. The relief generally lasts anywhere from several weeks to several months, depending on which joint was injected, what condition is being treated, and which steroid formulation was used. That wide range is not vagueness for its own sake; the evidence genuinely varies by body site and by individual, and it is worth understanding why.
What Happens in the First Few Days
A cortisone injection usually contains two things: a corticosteroid (the actual anti-inflammatory drug) and a local anesthetic like lidocaine. The anesthetic can numb the area almost immediately, which is why some people walk out of the office feeling better right away. That initial numbness wears off within hours, and there is often a gap before the steroid kicks in.
Corticosteroid formulations come in two broad categories. Ester forms like triamcinolone acetonide and methylprednisolone acetate are tiny crystals suspended in liquid. They dissolve slowly after injection, which gives them a longer-lasting but slower-starting effect. Non-ester forms like dexamethasone dissolve readily and act faster but wear off sooner.1PubMed Central. Local Anesthetics and Steroids: Contraindications and Complications – Clinical Update Most joint injections use one of the slower-release ester forms, so the full anti-inflammatory effect typically builds over a few days.
During that gap, roughly one in five people experience what is called a post-injection flare: a temporary spike in pain and swelling at the injection site. In one prospective study of 140 patients receiving musculoskeletal corticosteroid injections, about 21% reported a flare.2PubMed Central. Prospective Evaluation of Pain Flares and Time Until Pain Relief Following Musculoskeletal Corticosteroid Injections A study focused specifically on shoulder injections found a higher rate of about 35%, with the flare lasting an average of four days.3PubMed Central. The Incidence of Flare Reaction and Short-Term Outcome Following Steroid Injection in the Shoulder The flare is a reaction to the steroid crystals themselves irritating the tissue, not a sign that something went wrong. Ice and over-the-counter pain relievers usually manage it until the anti-inflammatory effect takes over.
Epidural Steroid Injections and the Speed of Onset
For epidural steroid injections used to treat back and leg pain from disc herniations or spinal stenosis, the timeline has been tracked more precisely. A study that followed 108 patients after epidural injections found that among those who eventually got meaningful relief (at least a 50% reduction in pain by the three-week mark), about 73% of them already felt that level of improvement on the very first day. Another 22% reached it by day four. Only a small handful of patients did not feel the benefit until the second or third week.4PubMed Central. How Soon After an Epidural Steroid Injection Can You Predict the Patient’s Response? So if an epidural injection is going to work for you, you will probably know within the first few days.
Whether that relief sticks around is a different question. A systematic review and meta-analysis in the Annals of Internal Medicine found that for radiculopathy (nerve-root pain radiating down a leg), epidural corticosteroid injections produced modest short-term improvements in pain and function compared to placebo, but no benefits at longer follow-ups.5PubMed. Epidural Corticosteroid Injections for Radiculopathy and Spinal Stenosis: A Systematic Review and Meta-analysis That said, individual variation is enormous. One study of caudal epidural injections for chronic low back pain found that the average duration of relief was about 38 weeks in patients without painful lumbar extension, but dropped to about 15 weeks in patients who did have pain with extension. And the range spanned from zero weeks to several years.6PubMed Central. Predictive Factors of the Effectiveness of Caudal Epidural Steroid Injections in Managing Patients With Chronic Low Back Pain and Radiculopathy
Duration of Relief in the Knee
Knee osteoarthritis is one of the most common reasons people get cortisone shots, and the evidence on duration here is a bit sobering. A meta-analysis in the BMJ found that corticosteroid injections for knee osteoarthritis still showed a meaningful improvement in symptoms at 16 to 24 weeks after injection, which suggests the effect can persist for four to six months in some patients.7BMJ. Corticosteroid Injections for Osteoarthritis of the Knee: Meta-analysis Another evidence review concluded that pain relief and functional improvement could be significant for months and potentially up to a year.8Pain Medicine. Evidence-Based Knee Injections for the Management of Arthritis
But a more recent systematic review and meta-analysis painted a less optimistic picture. It concluded that while cortisone injections for knee osteoarthritis do provide pain relief above placebo in the short term, the benefits lose clinical relevance after about six weeks.9PubMed. Intra-articular Corticosteroid Injections Provide a Clinically Relevant Benefit Compared to Placebo Only at Short-Term Follow-Up in Patients With Knee Osteoarthritis That discrepancy is worth understanding. Older studies sometimes lacked rigorous placebo comparisons, and patients receiving any injection, even saline, tend to report some improvement. The newer analysis specifically measured how much of the benefit exceeded the placebo effect, and found that the cortisone-specific advantage was relatively short-lived. This does not mean people imagined their relief, but it does suggest that part of the improvement many patients report at three or six months may be driven by the natural fluctuation of symptoms and the placebo response rather than the steroid itself.10PubMed Central. The Placebo Effect in Pain Therapies
Duration of Relief in the Shoulder
Shoulder injections, particularly for rotator cuff tendinitis, tend to have a moderate track record. A meta-analysis of subacromial corticosteroid injections found them effective for rotator cuff tendinitis for up to nine months.11PubMed Central. Corticosteroid Injections for Painful Shoulder: A Meta-analysis A Cochrane review was more cautious, noting that while injections for rotator cuff disease and adhesive capsulitis (frozen shoulder) may be beneficial, the effect can be small and may not be well maintained over time.12Cochrane Database of Systematic Reviews. Corticosteroid Injections for Shoulder Pain In practice, many clinicians find that shoulder injections provide meaningful relief for a few weeks to a few months, with diminishing returns on repeat injections.
Why the Same Shot Works Differently in Different People
Several factors explain why your neighbor got six months of relief from a knee injection and you got three weeks. The steroid formulation matters. Triamcinolone hexacetonide, one of the least soluble steroid esters, stays in the joint for two to three weeks, giving it one of the longest local durations of action.13PubMed. Intra-articular Corticosteroids. Guide to Selection and Indications for Use More soluble formulations clear the joint faster. Your doctor’s choice of steroid and dose will influence the result, though not every clinic stocks every option.
The accuracy of the injection also plays a role. An umbrella review comparing ultrasound-guided injections to the traditional landmark-guided approach (where the provider finds the injection site by feel) found that ultrasound guidance generally improved accuracy and outcomes, particularly for hip and knee joints.14PubMed Central. Comparison of Ultrasound- vs Landmark-Guided Injections for Musculoskeletal Pain: An Umbrella Review For shoulder injections, a systematic review found that ultrasound-guided subacromial injections produced significantly greater pain reduction and functional improvement at six weeks compared to landmark-guided ones.15British Journal of Sports Medicine. Ultrasound-Guided Shoulder Girdle Injections Are More Accurate and More Effective Than Landmark-Guided Injections: A Systematic Review and Meta-analysis A separate meta-analysis of subacromial impingement specifically confirmed that ultrasound guidance improved both pain and function.16PubMed Central. Effectiveness of Ultrasound-Guided Versus Anatomic Landmark-Guided Corticosteroid Injection on Pain, Physical Function, and Safety in Patients With Subacromial Impingement Syndrome If you are offered the choice, ultrasound guidance is worth asking about, particularly for deeper joints where a blind injection is more likely to miss.
What you do immediately after the shot matters too. A randomized controlled trial found that strict bed rest for 24 hours after a knee injection led to greater and longer-lasting improvement, potentially extending the benefit up to six months compared to the usual “go about your day” approach.17Rheumatology. A Randomized Controlled Study of Post-Injection Rest Following Intra-Articular Steroid Therapy for Knee Synovitis Even among high-level athletes, where returning to activity quickly is a priority, the recommendation is to rest the affected joint for at least one to two days before gradually increasing activity.18PubMed Central. One to Two Days of Rest Is Recommended Before Returning to Sport After Intra-Articular Corticosteroid Injection in the High-Level Athlete The logic is that resting the joint lets more of the steroid stay local rather than getting flushed out by blood flow during activity, and reduces potential stress on cartilage while the steroid is at its highest local concentration.
Blood Sugar Spikes if You Have Diabetes
One side effect that often catches people off guard is the temporary rise in blood sugar after a cortisone injection. Even though the shot goes into a joint or soft tissue, some of the steroid is absorbed into the bloodstream, and corticosteroids raise blood glucose. For people without diabetes, this is usually unnoticeable. For people with diabetes, it can be significant.
A study of patients with diabetes who received hand and wrist corticosteroid injections found that fasting blood glucose rose by an average of about 43 mg/dL on the first day after injection and about 17 mg/dL on day two, returning to baseline by day four.19PubMed Central. Blood Glucose Levels in Diabetic Patients Following Corticosteroid Injections Into the Hand and Wrist Patients with type 1 diabetes and those using insulin saw larger spikes. A similar pattern was confirmed in shoulder injections, where the mean glucose level rose from about 136 mg/dL before the injection to 159 mg/dL on day one and 154 mg/dL on day two. About 20% of the patients hit glucose readings above 350 mg/dL during the first three days.20JSES International. The Effect of Steroid Injection Into the Shoulder on Glycemia in Patients With Type 2 Diabetes A third study confirmed the spike typically resolves by day two for most patients, though people with poorly controlled diabetes (higher baseline HbA1c levels) experienced larger increases.21PubMed Central. Changes in Blood Glucose Level After Steroid Injection for Musculoskeletal Pain in Patients With Diabetes
If you have diabetes and are getting a cortisone shot, it is worth talking to your doctor in advance about adjusting insulin or oral medication for the first couple of days. The spike is temporary and predictable, but if you are caught unaware, it can lead to symptoms or worry.
Cartilage Damage and Repeat Injections
The concern about cortisone damaging joint cartilage over time is not unfounded, but the picture is more nuanced than the blanket warnings suggest. A systematic review of the effects of corticosteroids on cartilage found dose-dependent harm: at lower doses, the impact was less clear, but at higher doses (above about 3 mg per injection or cumulative totals around 18 to 24 mg in animal models), corticosteroids were associated with significant cartilage damage and death of chondrocytes, the cells that maintain cartilage.22PubMed Central. The Effect of Intra-articular Corticosteroids on Articular Cartilage: A Systematic Review This is one reason most providers limit repeat injections to the same joint, commonly recommending no more than three to four shots per year for a weight-bearing joint.
Skin-related side effects at the injection site are also possible. Subcutaneous fat atrophy, which shows up as a visible dent or thinning of the skin near the injection site, and lightening of the skin (hypopigmentation) can occur. These changes may resolve on their own, but it can take one to two years.23ReumatologÃa ClÃnica. Treatment of Persistent Cutaneous Atrophy After Corticosteroid Injection With Fat Graft Estimates of how often skin atrophy happens range widely, from under 1% to as high as 40% depending on the injection site and technique, while hypopigmentation has been reported in roughly 1% to 6% of cases.24PubMed Central. Delineating Injectable Triamcinolone-Induced Cutaneous Atrophy and Therapeutic Options in 24 Patients These side effects are more common with superficial injections near the skin surface (like trigger finger injections or keloid treatments) than with deep joint injections.
How Cortisone Compares to Platelet-Rich Plasma
Platelet-rich plasma (PRP) injections have become a popular alternative to cortisone, especially for conditions like tennis elbow and knee osteoarthritis. The pattern that emerges from the research is consistent: cortisone works faster, PRP lasts longer.
For lateral epicondylitis (tennis elbow), a systematic review found that cortisone injections gave rapid symptom improvement, peaking around six to eight weeks, after which symptoms tended to recur. PRP, by contrast, showed slower improvement that continued to build for six months to two years.25PubMed Central. The Effect of Corticosteroid Versus Platelet-Rich Plasma Injection Therapies for the Management of Lateral Epicondylitis: A Systematic Review For knee osteoarthritis, a trial comparing the two found that cortisone provided shorter-duration relief than PRP.26PubMed Central. Comparison of Efficiency Between Corticosteroid and Platelet Rich Plasma Injection Therapies in Patients With Knee Osteoarthritis
The trade-off is straightforward. If you need relief now, cortisone is the faster option. If you are looking for something that builds over time and may avoid the cartilage concerns associated with repeated steroid injections, PRP is worth discussing with your provider. PRP is rarely covered by insurance, however, and the evidence base, while growing, is less robust than what exists for corticosteroids. Multiple PRP formulations exist with no real standardization, so results vary across clinics in ways that make direct comparisons tricky. For many people, the practical choice is cortisone for acute flare-ups and PRP (or hyaluronic acid injections, physical therapy, and other options) as part of a longer-term management plan.