Cortisone is a synthetic corticosteroid, a potent anti-inflammatory medication injected directly into an area of pain or inflammation, such as a joint, tendon, or bursa. The primary purpose of a cortisone shot is to reduce swelling and pain, creating a window of opportunity for effective rehabilitation. By lowering the pain threshold, the injection allows a patient to engage in physical therapy (PT) and exercise that were previously too painful. The successful outcome depends on strategically timing the start of rehabilitation to maximize the drug’s anti-inflammatory effect and prevent complications.
Immediate Post-Injection Rest Period
The first 24 to 48 hours following the procedure require specific care to ensure the medication settles correctly in the targeted tissue. During this initial period, all strenuous activity and exercise should be avoided. Patients should limit heavy lifting and any movement that places unnecessary strain on the injection site.
Applying ice (15 to 20 minutes on and off) is recommended to reduce immediate swelling and soreness. Avoid heat application, such as heating pads or hot tubs, for at least two days, as heat can increase swelling and potentially interfere with the cortisone’s effectiveness. Patients should also monitor the injection site for any signs of infection, such as increased redness, warmth, or pain that persists beyond 48 hours.
Why a Waiting Period is Necessary
The delay in starting physical therapy is directly tied to the pharmacology of the injection itself. Cortisone, often mixed with a local anesthetic, requires time to be absorbed by the targeted tissues, such as the inflamed joint lining or bursa. Immediate pain relief is often due to the anesthetic, which wears off quickly, while the anti-inflammatory effects of the corticosteroid may not begin for 48 to 72 hours.
Starting high-impact activity too soon can mechanically stress the treated area before inflammation has fully resolved. Premature loading may inadvertently push the medication out of the joint space, reducing the drug’s concentration and duration of action. Furthermore, after the temporary anesthetic wears off, some patients experience a temporary increase in pain known as a “steroid flare,” which can last up to 72 hours. Rest allows the body to manage this spike in pain, ensuring the cortisone can initiate its long-term anti-inflammatory process.
General Timeline for Starting Physical Therapy
The standard recommendation for beginning structured physical therapy is between three and seven days following the injection. This range allows the cortisone to fully take effect and the acute post-injection discomfort to subside. The transition back to activity should be gradual, starting with gentle, low-impact movements.
Initial physical therapy sessions focus on passive range-of-motion exercises and light stretching to maintain mobility without stressing the healing tissue. High-impact activities, heavy resistance training, or strenuous workouts should be avoided for at least seven days. The patient’s response to the injection and initial exercises should guide the progression, with any increase in pain signaling the need to reduce intensity. This timeline must be tailored to the individual’s specific condition, requiring close communication with both the prescribing physician and the physical therapist.
Modifying the Timeline Based on Injection Site
The time required before starting physical therapy is not uniform and depends significantly on the location and nature of the injected tissue.
Non-Weight-Bearing Joints
For non-weight-bearing joints (e.g., elbow, wrist, or shoulder), the initial rest period is often shorter, allowing for gentle PT activities within three to five days. Some shoulder protocols recommend avoiding heavy movements for a minimum of two weeks to prevent overexertion due to potentially masked pain.
Weight-Bearing Joints
Injections into large weight-bearing joints (e.g., knee, hip, or ankle) necessitate a more conservative approach due to the risk of structural damage from early loading. For these areas, a waiting period closer to seven days, and sometimes up to 10 to 14 days, may be advised before initiating range-of-motion exercises.
Spinal Injections
Spinal injections, which often target inflamed nerves or facet joints, also require a longer period of caution. Patients are advised to avoid high-impact movements for at least a week to prevent premature stress on the affected area.