AFTERCARE GUIDE
Aftercare following a knee injection.
Steroid, viscosupplement (gel), PRP and Arthrosamid® injections. Read online or download a printable copy.
This guide explains what to expect after a knee injection and how to look after your knee. It covers the injections most often used for knee arthritis. Your clinician will tell you which injection you have had and any specific advice for you.
At a glance
| On the day | Walking is fine. Rest the knee from strenuous activity, long walks and sport for 24–48 hours |
| The injection site | Keep the plaster on and the area clean and dry for 24 hours. Avoid baths, swimming and hot tubs for 48 hours |
| Driving | Many people can drive afterwards, but it is safer to arrange a lift home on the day if you can |
| Pain relief | Paracetamol is usually fine. After PRP, avoid anti-inflammatory medicines unless advised (see below) |
| When it may help | Varies with the type of injection, from a few days to several weeks |
Steroid (corticosteroid) injection
- The knee may feel more sore for 24–48 hours (a “steroid flare”). Rest, ice and paracetamol usually help.
- Any benefit usually starts within a few days. NICE advises that steroid injections give short-term relief, usually for 2 to 10 weeks.
- If you have diabetes, your blood sugar may rise for a few days. Check it more often and follow your diabetes plan.
- Some people notice temporary facial flushing.
- NICE recommends them mainly to support exercise, or when other pain relief is not effective or suitable. Repeated injections are limited.
Viscosupplement (hyaluronic acid gel) injection
- Mild aching or swelling for a day or two is common.
- For the right type of arthritis, many patients report good symptom relief lasting up to six months.
- It is not recommended for advanced (“bone on bone”) arthritis.
- The injection can be repeated if it has helped.
- NICE does not recommend these injections for osteoarthritis in the NHS, because the evidence of benefit across all patients is limited. Some people choose them privately after discussing the likely benefit and limitations.
Platelet-rich plasma (PRP) injection
- PRP is prepared from your own blood. A blood test is usually done beforehand to check your baseline platelet levels.
- Current evidence favours a single high-concentration injection, so up to 60 ml of blood is usually drawn on the day to achieve an adequate platelet concentration. You may have a small bruise where the blood was taken.
- Soreness and stiffness for two to three days is common, as PRP causes a short-lived inflammatory response.
- Avoid anti-inflammatory medicines such as ibuprofen, naproxen or diclofenac for about two weeks, unless your doctor advises otherwise. Paracetamol is fine.
- Any benefit tends to develop over several weeks.
- NICE advises that PRP for knee osteoarthritis should only be used with special arrangements for consent and audit, because the evidence is still limited.
Arthrosamid® (polyacrylamide hydrogel) injection
- A promising newer treatment for selected patients. As it is new, long-term results are still limited.
- In published studies, about 6 in 10 patients had meaningful improvement at one year, and pain relief was maintained for up to three years in those followed up.
- Mild pain, swelling or stiffness for a few days is common.
- Avoid strenuous activity for the first few days, then build up gradually.
Keeping the benefit going
- Injections work best as part of a plan that includes regular exercise to strengthen the muscles around the knee, as recommended by NICE.
- Use any period of reduced pain to build up your exercise programme gradually.
When to seek urgent help
Call 999 if you have difficulty breathing, swelling of the face, lips or throat, or feel faint after an injection.
Contact the hospital or clinic where you were treated straight away (or NHS 111 out of hours) if:
- The joint becomes hot, red and very swollen, or the pain keeps getting worse after the first 48 hours
- You have a temperature above 38°C, shivering or feel generally unwell
- The injection site leaks fluid or looks infected
Sources
This guide is based on Mr Umar’s practice and is guided by NICE and British Orthopaedic Association (BOA) guidance:
- NICE NG226: Osteoarthritis in over 16s – diagnosis and management
- NICE HTG497 (formerly IPG637): Platelet-rich plasma injections for knee osteoarthritis
- Bliddal H et al. 2024. Polyacrylamide hydrogel injection for knee osteoarthritis: one-year results. J Orthop Surg Res
- Bliddal H et al. 2026. Three-year follow-up of a single polyacrylamide hydrogel injection for knee osteoarthritis. Clin Exp Rheumatol
- British Orthopaedic Association (BOA) – guidance and patient information
Questions?
| Spire Regency, Macclesfield | Denise Rowbotham · 01625 507472 |
| The Alexandra, Spire Manchester, Spire Hale and Circle Cheshire | Danielle Heron · 07528 523911 |
This is general guidance. Always follow the specific advice from your own clinical team, as your care may differ.