A cortisone shot (corticosteroid injection) is a common treatment for managing pain and inflammation within the knee joint. This procedure involves injecting a powerful anti-inflammatory medication directly into the affected area. The corticosteroid mimics the natural hormone cortisol, which possesses strong anti-inflammatory properties. It is frequently used to alleviate symptoms caused by localized conditions like osteoarthritis and various forms of tendonitis.
The Initial Timeframe for Pain Relief
The time it takes to feel relief from a knee cortisone shot can vary, but the process often begins almost immediately for some patients. This initial, rapid reduction in discomfort is not due to the cortisone itself but is caused by a local anesthetic, such as lidocaine, mixed with the corticosteroid medication. This numbing agent works right away, providing a temporary sense of relief that lasts for only a few hours.
Once the anesthetic wears off, the patient may experience a brief return of pain while the corticosteroid component begins its work. The cortisone is a slower-acting anti-inflammatory agent that needs time to suppress the chemical signals causing inflammation in the joint. Most people begin to notice the therapeutic effect of the steroid starting within two to five days following the injection.
The full anti-inflammatory action of the cortisone usually becomes noticeable within five to seven days. However, in cases of severe or chronic inflammation, it can sometimes take up to two or even six weeks to experience the maximum benefit. Timing is influenced by the type of corticosteroid used, the severity of the underlying condition, and the individual patient’s response.
Potential Temporary Post-Injection Reaction
Some people experience a temporary increase in pain and swelling at the injection site, commonly called a “cortisone flare” or “steroid flare.” This reaction occurs before the medication’s intended anti-inflammatory effect takes hold. The flare-up is thought to be caused by the body’s local reaction to the injected microcrystals of the corticosteroid solution.
These steroid crystals can irritate the joint lining or surrounding tissues, triggering a short-lived inflammatory response that temporarily worsens symptoms. The increased discomfort typically peaks within the first 24 hours after the procedure. This temporary aggravation usually subsides on its own within 48 to 72 hours, which is around the same time the steroid begins to provide relief.
Managing a cortisone flare primarily involves simple home care measures to reduce the localized irritation. Applying ice to the injection site for short intervals helps decrease local swelling and discomfort. Patients should also rest the joint and avoid strenuous activity during this initial period, using over-the-counter pain medication if recommended by their doctor.
Expected Longevity and Treatment Frequency
Once the corticosteroid takes full effect, the duration of pain relief it provides can vary significantly. Generally, patients can expect the benefits of a cortisone shot in the knee to last anywhere from two to six months. For conditions like knee osteoarthritis, the shot offers temporary symptom management rather than a cure, as it does not repair damaged cartilage or address the underlying cause of the disease.
The effectiveness of the injection may begin to diminish over time, particularly with chronic conditions where the underlying joint damage continues to progress. If the shots are repeated, some patients find that the period of relief from subsequent injections becomes shorter. This decrease in longevity signals that the condition may be worsening or that alternative treatment strategies should be considered.
Healthcare providers limit the frequency of these injections to mitigate the risk of complications. Most orthopedic specialists recommend receiving no more than three or four cortisone shots in the same knee joint over a period of one year. Injections are typically spaced at least 12 weeks apart to allow the joint time to recover and minimize the cumulative effect of the medication.
Receiving too many injections too frequently can potentially lead to adverse effects, including damage to cartilage, ligaments, and tendons. If the pain relief becomes short-lived or the injections cease to be effective, doctors will often pivot to a different treatment plan. This may include alternative non-surgical options like physical therapy, or in severe cases, discussion of surgical intervention to address the structural issues causing the knee pain.