What to Do After a Knee Injection

Rest the knee for at least a day, apply ice if the area is sore, and avoid intense physical activity for roughly 24 to 48 hours. That is the short version, but the details matter because what you do in the hours and weeks after a knee injection meaningfully affects how much relief you get and how long it lasts. The type of injection you received, whether corticosteroid, hyaluronic acid, or platelet-rich plasma, also changes the timeline for what comes next.

The First 24 to 48 Hours

The single most consistent recommendation across sports medicine and rheumatology research is to rest the injected knee for one to two days. A study in high-level athletes found that one to two days of rest followed by a gradual increase in activity helped maximize the injection’s benefits and reduced the steroid’s systemic effects on the body.¹ Earlier research in inflammatory arthritis patients went further, showing that a full 24 hours of strict bed rest after a steroid injection produced greater clinical improvement that lasted up to six months compared with patients who simply went home and resumed normal activity.²

You do not need to stay in bed for 24 hours in most cases. The practical takeaway is to keep weight-bearing to a minimum for the rest of that day, skip the gym, and avoid standing for long periods. Light walking around the house is fine. Use ice wrapped in a cloth for 15 to 20 minutes at a time if the injection site feels sore or warm. Avoid heat, hot tubs, and baths for at least a day, because warmth can increase swelling and theoretically raise infection risk around the puncture site.

Post-Injection Pain Flares Are Normal

A temporary surge in knee pain after an injection catches many people off guard, but it is a well-documented response. In a prospective study of 140 patients who received corticosteroid injections, about one in five experienced a flare of pain in the days afterward. Younger patients had higher odds of developing a flare, while gender, body mass index, and injection location did not seem to matter.³ Other research has reported even higher rates, with about a third of patients noting increased pain in the first day or two after a steroid injection.⁴

These flares are caused by a reaction to the injected material itself, sometimes called a crystalline flare because the steroid crystals irritate the joint lining before they dissolve. The pain usually peaks within the first 24 hours and fades within two to three days. Over-the-counter pain relievers and icing the knee are the go-to remedies. If the flare lasts beyond three days, gets progressively worse rather than better, or comes with a fever, that changes the picture and warrants a call to your doctor.

Can You Drive Home After the Injection?

Many clinics tell patients to arrange a ride, but the evidence suggests driving is not actually dangerous after a knee injection. A study that measured braking reaction time before and after intra-articular knee injections found no significant difference. The average braking time was essentially the same, and the rate of failed braking attempts did not increase after the procedure.⁵ If your injection involved a local anesthetic mixed in with the steroid, your knee might feel numb for an hour or two. In that scenario, waiting 30 to 60 minutes before getting behind the wheel is reasonable. But the injection itself does not impair your ability to operate the brake pedal.

When to Worry and What Red Flags Look Like

Infection after a knee injection is rare but serious. A 17-year retrospective study at an academic hospital found that septic arthritis occurred most often after corticosteroid injections and most frequently involved knees, with patients who had a history of multiple injections or weakened immune systems at higher risk.⁶ The complication is uncommon enough that most people who get knee injections will never encounter it, but recognizing the signs matters because delayed treatment leads to worse outcomes.

The tricky part is that early infection can look deceptively mild. One case report described a patient whose septic arthritis developed slowly over a week, with gradually worsening knee pain, limited swelling, and no fever.⁷ Because a post-injection flare also causes pain and some swelling, it is easy to dismiss early infection as a normal reaction. The key differences to watch for are:

Timing: A flare peaks in the first 24 hours and improves. Infection-related pain starts improving and then reverses, or simply never improves at all beyond the first couple of days.
Fever or chills: A pain flare does not cause systemic symptoms. If you feel feverish or unwell, contact your doctor immediately.
Redness spreading: Some redness at the injection site is normal. Redness that expands outward from the knee or appears streaky is not.
Increasing swelling: A joint that keeps getting puffier day after day rather than settling down needs evaluation.

When in doubt, calling your provider’s office is always the right move. A simple exam and sometimes a fluid sample from the joint can quickly distinguish a flare from something that needs treatment.

How Quickly Relief Kicks In Depends on What Was Injected

Not all knee injections work on the same timetable. Corticosteroid injections tend to provide relief within a few days and are most effective for short-term pain reduction in moderate to severe osteoarthritis.⁸ If you received a steroid injection and feel no improvement after a week, it may not have worked well for your particular situation. The relief from a steroid injection typically fades over weeks to a few months.

Hyaluronic acid injections work differently. They act more like a lubricant and shock absorber in the joint and tend to take longer to show results, sometimes a few weeks. The benefit can last up to about six months, and the research suggests they may work best in milder osteoarthritis.⁸ If you just got a hyaluronic acid injection and feel nothing after four days, that is expected. Give it time.

Platelet-rich plasma (PRP) injections have a different profile again. A randomized trial comparing PRP, hyaluronic acid, and daily anti-inflammatory medication over a year found that PRP produced better pain and function scores than both other treatments.⁹ PRP relies on your body’s own healing response, so the initial period may involve more discomfort and swelling than a steroid injection. Most practitioners recommend avoiding anti-inflammatory painkillers for at least a few days after PRP because those medications may blunt the inflammatory cascade the injection is trying to trigger.

Getting Back to Exercise

Once the initial rest period passes, movement is not just allowed but encouraged. The goal of most knee injections is to create a window of reduced pain that lets you do the things your knee was too sore for before, especially strengthening exercises. Research looking at physical therapy alongside injection therapy found that patients who started physical therapy sooner after their osteoarthritis diagnosis were less likely to need additional injections down the road. Those who waited nine to twelve months before starting physical therapy had a notably higher chance of needing more injections than those who began within a month.¹⁰

That finding underscores something many orthopedic specialists emphasize: an injection is not a standalone fix. It buys you time and comfort so you can strengthen the muscles around the knee, improve flexibility, and work on biomechanics. Quadriceps strengthening in particular is consistently linked with better knee function and less pain. Start with low-impact activities like cycling, swimming, or gentle resistance exercises in the first week, and build from there. High-impact sports or heavy lifting should wait until the knee has had a week or two to settle, consistent with the progressive return-to-activity approach recommended after steroid injections.

Knee Bracing as a Complement

If you have more advanced osteoarthritis, wearing a brace alongside your injection may improve results. A study of patients with high-grade knee osteoarthritis found that combining hyaluronic acid injections with a knee brace significantly improved clinical outcomes, with bracing providing a strong complementary effect.¹¹ An unloader brace, the kind that shifts weight off the damaged compartment of the knee, is the type most commonly studied. These are worth asking your doctor about if your osteoarthritis is concentrated on one side of the joint.

Blood Sugar Concerns If You Have Diabetes

Corticosteroids raise blood sugar. This happens even when the steroid is injected directly into a joint rather than taken systemically, and people with diabetes need to plan for it. A study of diabetic patients who received steroid injections found that blood glucose rose significantly on the day after the injection but returned to baseline by the second day. Patients with higher baseline blood sugar levels (measured by HbA1c above 7%) and those taking insulin experienced larger spikes.¹²

Separate research echoed the same pattern, finding a transient rise in blood glucose that was more pronounced in type 1 diabetics and those using insulin. The authors recommended vigilant glucose monitoring and potential medication adjustments in the days following injection, particularly for patients whose glucose had been unstable beforehand.¹³ In practical terms, if you have diabetes and just had a corticosteroid knee injection, plan to check your blood sugar more frequently for at least 48 hours and talk to whoever manages your diabetes medication before the injection if possible.

Repeated Steroid Injections and Long-Term Cartilage Health

There is an honest tension in the data here. Corticosteroid injections are effective for short-term pain relief, but laboratory and animal research has consistently shown that corticosteroids can damage cartilage in a dose- and time-dependent way. A systematic review found that low doses and short exposures actually helped cartilage cells recover, but higher doses and repeated exposure were associated with gross cartilage damage and cell death.¹⁴

This is why most doctors limit corticosteroid knee injections to three or four per year in the same joint. The exact threshold varies by provider and the steroid used, but the principle is the same: each injection trades some potential long-term cartilage integrity for short-term comfort. If you find yourself needing frequent steroid injections, it is worth having a conversation about switching to hyaluronic acid, exploring PRP, or discussing whether surgical options have become appropriate. The injection should be part of a broader management plan, not the entire plan.

Weight Management and the Bigger Picture

Injections address symptoms, not the underlying mechanical problem. For people with knee osteoarthritis who are carrying extra weight, losing even a modest amount can improve pain, stiffness, and function without any adverse effects.¹⁵ Every pound of body weight translates to roughly three to four pounds of force across the knee during walking, so the arithmetic adds up quickly. The challenge, of course, is that knee pain makes exercise harder, which makes weight loss harder. That is precisely why the pain-relief window from an injection is so valuable: use it to move more, build muscle, and ideally drop some weight before the injection wears off.

How Your Expectations Affect Your Results

This is one of the more surprising findings in the injection literature. A study looking at hyaluronic acid injections found that patients who went in with higher expectations of improvement had better function scores at six months and showed greater improvement from their baseline. The researchers attributed this largely to the placebo phenomenon, where expecting pain relief appears to reduce awareness of osteoarthritis symptoms and produce real analgesic effects.¹⁶ Conversely, patients with higher psychological stress had worse outcomes.

None of this means knee pain is “in your head.” Osteoarthritis is a real structural disease. But the brain’s pain-processing system is deeply tied to expectation and emotional state. If you go into an injection convinced it will fail, you may get less out of it. If you pair the injection with active rehabilitation and a genuine belief that it is one useful tool in a larger toolkit, you are more likely to report meaningful improvement. This is not woo; it is a measurable effect that shows up in validated outcome scales.

A Quick Reference for the First Week

Because the practical logistics are what most people want pinned down, here is a day-by-day framework for after a corticosteroid or hyaluronic acid knee injection:

Day of injection: Rest the knee. Ice as needed. Keep the bandage on for a few hours. Avoid baths, pools, and hot tubs. Driving home is acceptable if you feel comfortable.
Days 1 to 2: Expect some soreness or a flare. Light walking around the house is fine. Continue icing. Monitor for red flags like spreading redness, fever, or worsening pain that does not respond to ice or over-the-counter medication.
Days 3 to 5: Pain from the injection itself should be fading. If you received a steroid, you may start noticing improvement in your baseline knee pain. Resume light daily activities.
Days 5 to 7: Begin gentle strengthening and range-of-motion exercises. Swimming, stationary cycling, and short walks are good starting points. Avoid deep squats, heavy lifting, and high-impact sports for now.
Week 2 onward: Gradually increase activity level. This is the window to engage with physical therapy or a home exercise program in earnest.

For PRP injections, the timeline shifts. Expect more soreness in the first few days, avoid anti-inflammatory medications unless your doctor says otherwise, and do not judge the injection’s effectiveness until at least four to six weeks have passed.

If you have diabetes, add frequent blood sugar checks for the first 48 hours after any corticosteroid injection. Have a plan in place with your diabetes care provider before the procedure so you know how to adjust your medication if your readings spike.