Cortisone injections

What is a cortisone injection, and how does it work?

A cortisone injection (the clinical name is corticosteroid injection) puts a small amount of anti-inflammatory steroid medicine into or around a painful or swollen joint, or soft tissue such as a tendon sheath (the lining around a tendon) or a bursa (a small fluid-filled cushion)¹. It calms inflammation, which can ease pain, swelling and stiffness, and it works like cortisol, a hormone your body makes naturally². A local anaesthetic is often added to numb the area for a few hours³.

What is it used for, and how well does it work?

It's used for osteoarthritis (wear in a joint), bursitis, tendon problems, frozen shoulder, trigger finger and de Quervain disease (pain on the thumb side of the wrist)¹⁴. How well it works depends on the condition, and the best-supported benefit is short-term pain relief.

• Frozen shoulder: it eases pain in the short term more than physiotherapy or no treatment, and its edge may last some months⁵⁶.
• Trigger finger: it works better than a placebo (dummy) injection⁷.
• Knee osteoarthritis: it can ease pain and improve function for a few weeks, but there's no clear benefit by 26 weeks⁸. Repeated injections over 2 years eased pain no better than saline and led to more cartilage loss⁹. Guidelines still recommend it for knee and hip osteoarthritis¹⁰.
• Plantar heel pain: it's sometimes listed as a condition where injections may help¹, but how well it works for the heel isn't clear yet.

Relief often starts within 24–48 hours, sometimes up to a week, and lasts from a few weeks to several months¹. It varies between people, and a few get no benefit³.

Is a cortisone injection right for me?

It suits people who are likely to benefit and have nothing that makes an injection unsuitable, so the doctor will check this first¹¹. It shouldn't go ahead if you have an infection in the area or elsewhere in your body, a fever, a skin problem at the injection site, an allergy to the steroid or local anaesthetic, or poorly controlled diabetes, or if you feel unwell or have surgery planned in that area soon¹¹¹². An injection in the weeks before arthroscopy (keyhole joint surgery) is linked with more infections afterwards¹³, so tell your surgeon and ask about timing.

Tell the doctor about all your medicines and vaccinations, and if you have a weakened immune system or are pregnant or breastfeeding¹³. For a child, ask the doctor whether it's suitable.

What happens during and after the injection?

Before the injection, the doctor explains the procedure and risks and checks it's suitable for you². It's a prescription medicine, usually given by a specially trained doctor in a GP clinic or hospital clinic¹⁴, using a sterile technique¹⁵. Ultrasound is sometimes used to guide the needle, which places it more accurately. It's strongly recommended for the hip but not required for knee or hand joints¹⁶¹⁰. The medicine and amount depend on the joint or tendon being treated, so ask your doctor how many injections they suggest and how far apart.

Afterwards, the numbness from the local anaesthetic wears off after a few hours. You may then have mild soreness, called a steroid flare, for 24–48 hours until the steroid starts to work¹.

What are the risks and side effects?

Serious problems are rare¹⁷. Joint infection happens in about 1 in 10,000 procedures³; it's serious and is treated with intravenous antibiotics in hospital¹⁸. A severe allergic reaction (anaphylaxis) is very rare and usually happens within minutes of the injection¹⁷. Repeated injections raise the chance of a tendon or ligament rupture¹⁷. Injections may also temporarily raise blood pressure if you have high blood pressure². The warning signs are listed under "When to see a podiatrist".

How does it compare with other options?

For tendon problems, an injection often eases pain sooner, but it doesn't do better than physiotherapy or exercise beyond the short term. In rotator cuff tendinopathy (shoulder tendon pain) it seemed no more effective than physiotherapy at mid- and long-term follow-up¹⁹. In tennis elbow, physiotherapy did better over the long term, and injection was linked with more recurrence¹⁶; it also did worse than a placebo injection at 1 year²⁰. In gluteal tendinopathy (pain at the outer hip), education on load management plus exercise did better than injection at 8 months¹⁶.

So it works best as a short-term aid within a wider plan, not a stand-alone fix. Simple self-care and exercise-based care are a sensible first step for tendon problems. If an injection gives you a pain-free window, that's a good time to start or build up your exercises.