Joint injections for knee and shoulder pain: what to expect

Written by Dr Saptarshi Saha, MBBS, FRCGP, GP, Aarva.

A joint injection places an anti-inflammatory medicine directly into, or around, a painful knee or shoulder. For the right person it can ease pain for several weeks or months and make it easier to keep moving and doing the exercises that help most in the long run. It is not a cure, and it is not the right choice for everyone, which is why a proper examination comes first.

Joint injections are part of our private GP service. Here is what to expect, from the first assessment to the days after the injection.

Who might benefit from a joint injection?

Joint injections are most often considered for:

• Knee osteoarthritis, especially during a flare of pain and swelling
• Shoulder pain from irritation of the tendons and the fluid-filled sac at the top of the shoulder, often called subacromial pain
• Frozen shoulder, particularly in the early, painful stage

In line with NICE guidance, exercise, strengthening, weight management where relevant and simple pain relief come first. An injection is usually considered when these have not given enough relief, or when pain is stopping you from doing the exercises that would help. It works well alongside physiotherapy, not instead of it.

Why the assessment matters

Knee and shoulder pain have many causes, and not all of them respond to an injection. Pain felt in the shoulder can come from the neck. Knee pain can come from the hip. A torn tendon or a joint that locks may need a scan or a specialist opinion rather than an injection.

So the appointment starts with questions and an examination. Your doctor will ask when the pain started, what makes it worse, whether you have had an injury, and how it affects sleep, work and exercise. We will also go through your general health and any medicines you take. Sometimes the honest conclusion is that an injection is not the right step yet, and we will tell you that.

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Is a joint injection safe for me?

For most people, yes, but there are situations where your doctor may advise waiting or choosing a different approach. Tell us if any of these apply:

• You have diabetes, as the injection can raise blood sugar for a few days
• You take blood-thinning medicines
• You have any infection, including a skin infection near the joint
• You are planning joint replacement surgery, as surgeons often prefer a gap between an injection and an operation
• You have had several injections into the same joint already
• You are pregnant or could be

There is a limit to how often a single joint can be injected. Injections are usually spaced several months apart, and repeated injections into the same joint are kept to a small number each year.

What happens on the day of the injection?

Injections are not given in the same appointment as your first assessment. Your doctor confirms the price before anything goes ahead, and you decide whether to go ahead.

On the day, your doctor will check nothing has changed and talk you through consent, including the risks. The skin is cleaned carefully and the injection is given using a sterile technique. It often contains a local anaesthetic as well, so the joint may feel easier within minutes. The whole procedure takes a few minutes, and most people describe it as uncomfortable rather than painful.

What to expect afterwards

The first few days

Rest the joint for a day or two and avoid heavy lifting or strenuous exercise. The local anaesthetic wears off after a few hours, and some people have a temporary flare of pain for a day or two before the anti-inflammatory effect starts. Ice and simple pain relief can help.

How long does it last?

Relief usually builds over the first week. It can last anywhere from a few weeks to several months, and it varies a great deal between people. Some people notice little change. We use the pain-free window to build strength and movement, because that is what tends to keep the benefit going.

Possible side effects

• A short-lived increase in pain
• Facial flushing for a day or so
• Raised blood sugar for a few days if you have diabetes
• Thinning or lightening of the skin at the injection site, which is uncommon
• Infection in the joint, which is rare but serious

When to see a doctor sooner

After a joint injection, get medical advice the same day if the joint becomes increasingly hot, red, swollen or painful, especially after the first 48 hours, or if you develop a fever or feel generally unwell. These can be signs of infection. Contact us, your NHS GP or NHS 111, or go to A&E if you cannot reach anyone.

Whether or not you have had an injection, seek help promptly for:

• A hot, swollen joint with a high temperature
• A joint that suddenly swells after an injury, or that you cannot put weight on
• Shoulder or arm pain together with chest pain, breathlessness or sweating. Call 999
• Pain that wakes you every night, or comes with unexplained weight loss or a history of cancer
• A knee that repeatedly locks or gives way

This list is not exhaustive. If you are not sure about something, see a doctor.

If knee or shoulder pain is stopping you from doing what you want to do, book a consultation with a doctor to talk through your options, or use find your starting point to see which appointment suits you.

This article is general information and does not replace a consultation with a doctor.