Cortisone injections use corticosteroid medication to reduce inflammation and relieve pain in targeted areas like joints, tendons, and soft tissues. The powerful anti-inflammatory action provides significant, often long-lasting relief for conditions such as arthritis, bursitis, and tendinitis. Despite their therapeutic benefits, these injections carry potential negative outcomes and risks. These disadvantages range from temporary discomfort immediately following the shot to rare, serious complications affecting the injection site and the body’s overall function.
Common Short-Term Reactions
The most frequent negative experience is a temporary “post-injection flare” or “steroid flare.” This involves a brief increase in pain, swelling, and inflammation at the injection site, which is confusing since the injection’s purpose is to reduce these symptoms. The flare is caused by the body’s reaction to the crystalline nature of the corticosteroid before the drug dissolves and begins its anti-inflammatory work, typically resolving within 24 to 48 hours.
Some patients may experience transient systemic effects, most notably facial or body flushing. This involves a sensation of warmth and visible redness on the skin, which is a mild, self-limiting reaction that usually dissipates within a few hours. Corticosteroids can also temporarily elevate blood glucose levels, which is important for diabetic patients to monitor closely for several days. These short-term reactions are generally mild, require no medical intervention, and confirm that the body is processing the medication.
Localized Complications at the Injection Site
A more persistent concern relates to physical and cosmetic changes occurring near the injection site. Subcutaneous fat atrophy is a localized disadvantage where cortisone dissolves the fat tissue beneath the skin, leading to a visible depression or dimpling. The incidence of fat atrophy has been reported to range from 1.5% to 40% in some studies, and while it often resolves spontaneously, this process can take anywhere from six months to two years.
Another cosmetic side effect is skin depigmentation (hypopigmentation), resulting in a lightening of the skin at the injection site. This effect is due to the corticosteroid inhibiting melanocytes, the cells responsible for producing skin pigment, and is more noticeable in individuals with darker skin tones. Hypopigmentation occurs in an estimated 1.3% to 6% of patients and may take many months to resolve, though cases of permanent change have been reported.
Of greater structural concern is the risk of tendon or ligament weakening, particularly when injections are given too close to a tendon. Corticosteroids can locally decrease collagen production and inhibit tenocytes, the cells that maintain tendon structure, limiting the tissue’s ability to heal. This degradation can increase the risk of a full-thickness tendon rupture, which may occur anywhere from two days to six weeks after the procedure. Medical professionals typically limit the frequency of injections into a single site to minimize the potential for chronic tissue damage and structural failure.
Understanding Serious but Rare Adverse Events
While most side effects are temporary or localized, patients should be aware of rare, serious complications that require immediate attention. The most severe infectious risk is septic arthritis, an infection within the joint space caused by bacteria introduced during the injection process. Symptoms include rapidly escalating pain that is far worse than a typical steroid flare, combined with fever, intense joint warmth, and swelling. This complication is uncommon but necessitates urgent medical intervention to prevent permanent joint destruction.
Accidental nerve damage is another infrequent but serious adverse event, caused by either direct needle trauma or chemical irritation from the medication. Patients may experience temporary or, in rare cases, permanent numbness, tingling, or weakness that follows the path of the affected nerve. The risk of such injury is significantly reduced when injections are performed by experienced practitioners using imaging guidance, such as ultrasound or fluoroscopy.
Finally, a severe allergic reaction (anaphylaxis) is an extremely rare but life-threatening possibility. Signs of this reaction, which usually appear within minutes of the injection, include difficulty breathing, swelling of the face or throat, a full-body rash, and a rapid drop in blood pressure. Prompt recognition and immediate emergency medical treatment are necessary if these symptoms appear.