A cortisone shot in the knee is a common medical procedure designed to alleviate pain and reduce inflammation within the joint. These injections contain corticosteroids, which are synthetic versions of cortisol, a hormone naturally produced by the adrenal glands. Corticosteroids work by suppressing the immune system’s response in the targeted area, thereby decreasing swelling and pain associated with conditions like arthritis or injuries. This provides temporary relief from discomfort and improving mobility.
Right After the Shot
Immediately following a cortisone injection in the knee, you may experience some specific sensations as the local anesthetic begins to wear off. The injection includes both a corticosteroid and a fast-acting anesthetic, such as lidocaine or bupivacaine, to provide immediate pain relief. As this anesthetic fades, usually within a few hours, it is common to notice a return of pain or even a temporary increase in discomfort.
This temporary worsening of pain, often referred to as a “cortisone flare,” can occur in the first 24 to 48 hours after the injection. It happens as the corticosteroid begins its anti-inflammatory action, and the initial numbing effect subsides. You might also observe mild swelling, stiffness, or warmth around the injection site. Resting the knee and applying an ice pack can help manage these immediate post-injection symptoms.
Managing Symptoms and Recovery
The full therapeutic effects of the cortisone injection do not become apparent immediately. It takes three to seven days for the corticosteroid to reduce inflammation and pain. During this period, it is recommended to avoid strenuous activities.
Common side effects include temporary facial flushing (a feeling of warmth and redness in the face). Localized skin changes at the injection site, like temporary lightening or thinning, may also occur, though these are transient. For individuals with diabetes, a temporary elevation in blood sugar levels is a known possibility following a cortisone shot. These injections offer temporary symptom relief and do not cure the underlying cause of the knee condition.
When to Contact Your Doctor
While cortisone injections are generally safe, certain symptoms warrant immediate medical attention. You should contact your doctor if you experience:
- Severe, worsening pain in your knee that does not respond to typical pain relief measures.
- Signs of infection at the injection site, such as increasing warmth, significant redness, pus discharge, or severe swelling.
- New numbness or weakness in the leg or foot after the injection.
- Symptoms of an allergic reaction, such as a widespread rash, hives, or difficulty breathing.
These “red flag” symptoms are distinct from the expected mild and temporary side effects and suggest a potential complication.