Does the cortisone injection work immediately?

No, it generally takes 24 to 72 hours to feel noticeable improvement. Peak effectiveness is reached around day 5 to day 7. A mild inflammatory flare may occur within the first 24 hours.

Can I get another cortisone injection if the pain returns?

Yes, but not exceeding 3 to 4 injections per year at the same site. A minimum interval of 3 months between two injections is recommended to limit risks.

Why does my pain return after a few weeks?

Cortisone treats inflammation but not the underlying cause (muscle weakness, biomechanical imbalance, overuse). This is why physiotherapy is essential as a complement for lasting results.

Are there long-term side effects?

Repeated injections can weaken tendons, atrophy local subcutaneous fat, or accelerate cartilage degradation. Respecting intervals and the maximum number of injections is therefore crucial.

Does ultrasound-guided injection improve the duration of action?

Yes, because the medication is deposited exactly at the pathological site, which optimizes efficacy and can prolong the duration of relief compared to a less precise blind injection.

How Long Does a Cortisone Injection Last? Duration, Efficacy & Limits

Duration of Action of Cortisone: What the Studies Say

Cortisone injection (corticosteroids) is one of the most prescribed treatments for inflammatory musculoskeletal conditions. But one question keeps coming up: how long does its effect last? The answer depends on several factors that we detail here.

Onset of Action

Cortisone does not work instantly. Allow:

24 to 72 hours to feel the first effects
3 to 7 days for maximum relief
Sometimes an initial inflammatory flare-up ("flare reaction") within the first 24 hours

Duration of Relief

The duration of effectiveness varies depending on the pathology being treated and the type of corticosteroid used:

Bursitis: 4 to 12 weeks, sometimes definitive relief
Tendinopathies: 2 to 6 weeks (often used as a "therapeutic window" to begin rehabilitation)
Knee osteoarthritis: 4 to 8 weeks
Adhesive capsulitis (frozen shoulder): several months
Carpal tunnel syndrome: 1 to 6 months depending on severity

Long-acting corticosteroids (such as triamcinolone acetonide) offer a longer duration of action than fast-acting corticosteroids (such as betamethasone).

How Many Injections Per Year?

The general rule is not to exceed 3 to 4 injections per year per site. This limitation aims to avoid:

Weakening of tendons (risk of rupture)
Skin atrophy and local depigmentation
Cartilage damage (corticosteroid arthropathy)
Systemic effects (hyperglycemia, adrenal suppression, immune suppression)

It is essential to use cortisone injections judiciously, as a tool to calm acute inflammation and create a therapeutic window for rehabilitation, rather than as a recurring long-term solution.