A cortisone shot in the hamstring typically brings noticeable pain relief within three to five days, though the first 48 hours can feel worse before they feel better. About one in five people experience a temporary pain flare right after the injection, and nearly everyone needs a short rest period before returning to normal activity. Here’s what the recovery timeline actually looks like.
The First 48 Hours
The injection site will likely feel sore, and you may notice some swelling or stiffness in the back of your thigh. This is normal. The first 24 hours should be spent in relative rest to give the medication time to absorb and to let you monitor for any unusual reactions. That means staying off your feet as much as reasonable, icing the area if it’s uncomfortable, and avoiding any exercise that loads the hamstring.
After 24 to 48 hours, you can start light, progressive activities. Cycling on a stationary bike, using an elliptical, or doing gentle bodyweight exercises are all appropriate at this stage. The goal is gradual loading, not jumping straight back into sprints or heavy deadlifts.
The Post-Injection Pain Flare
Roughly 20% of people who get a cortisone injection experience what’s called a “steroid flare,” a temporary spike in pain, swelling, and irritation at the injection site. It can feel alarming, especially if you expected immediate relief. The flare typically lasts up to two days and then fades on its own.
If you do get a flare, expect your overall recovery to take a bit longer. People who experience one average about 4.5 days before they start feeling real improvement, compared to about 3 days for those who don’t. Ice and over-the-counter pain relievers can help you ride it out.
When Relief Kicks In
Half of patients report meaningful improvement by day three. Over 60% feel better within the first three days, and by day eight, roughly 95% have noticed a clear reduction in pain. So if you’re on day two and still uncomfortable, that’s completely expected. The cortisone needs time to reduce inflammation in the tissue.
If you’re past the two-week mark and haven’t noticed any change, the injection may not have been effective for your particular issue. Some hamstring problems, especially chronic tendon injuries with structural damage, respond less predictably to cortisone than acute inflammatory conditions.
Returning to Exercise and Sport
The standard recommendation is one to two days of rest followed by a progressive ramp-up. For lower-extremity injections specifically, that progression looks something like this:
- Days 1 to 2: Relative rest. Walking is fine, but avoid running, jumping, or heavy lifting.
- Days 2 to 4: Low-impact cardio like cycling or elliptical work, plus bodyweight exercises that don’t aggressively stretch or load the hamstring.
- Days 4 to 7: Gradual return to sport-specific movements, increasing intensity as pain allows.
This approach serves two purposes. It gives the medication time to work at its fullest and reduces the chance of systemic side effects. Even professional athletes follow this protocol. Pushing hard too early doesn’t just risk re-aggravating the hamstring; it can also reduce how well the injection works, since the medication hasn’t had time to settle into the inflamed tissue.
Physical therapy can resume after the initial one-to-two-day rest window. In fact, pairing a cortisone shot with a structured rehab program is one of the most effective strategies for hamstring tendon problems. The injection creates a window of reduced pain that lets you do the strengthening work that addresses the underlying issue.
Possible Side Effects
Most side effects are local and temporary. Beyond the pain flare described above, a few things can happen at the injection site over the following weeks and months.
Skin lightening (hypopigmentation) occurs in roughly 1% to 4% of patients. It shows up one to four months after the injection, which means you might not connect it to the shot at first. The discoloration is cosmetic, not harmful, and resolves on its own within six to 30 months. It tends to be more noticeable in people with darker skin tones.
A small dimple or indentation can develop if the cortisone causes some thinning of the fat layer under the skin. This subcutaneous fat atrophy typically reverses within six to 12 months. It’s more common when the injection is placed close to the surface rather than deep in the tissue.
Tendon Rupture Risk
This is the concern most people have heard about, and the data is reassuring. In a retrospective study of patients who received cortisone injections around the proximal hamstring tendon (where it attaches near the sit bone), no tendon ruptures occurred. Across two large reviews covering nearly 2,000 patients who received cortisone injections for various tendon problems, only a single rupture was reported, and it involved the Achilles tendon, not the hamstring.
The risk appears to increase when cortisone is injected directly into the tendon rather than around it. Most practitioners specifically aim for a peritendinous placement, meaning the medication goes into the tissue surrounding the tendon, not the tendon itself. Imaging guidance like ultrasound or fluoroscopy further reduces the risk of accidental intratendinous injection.
Signs Something Is Wrong
Serious complications are rare, but worth knowing about. An infection at the injection site, while uncommon, would show up as increasing redness and swelling (not improving after 48 hours), warmth over the area, fever or chills, and worsening pain rather than the gradual improvement you’d expect. If the area becomes increasingly hard or swollen and you develop a fever, that warrants prompt medical attention.
The key distinction: a steroid flare gets worse for a day or two and then clearly improves. An infection gets progressively worse without a turning point. If your pain is still escalating past the 48-hour mark, don’t assume it’s just a flare.
How Long Relief Lasts
A single cortisone injection is not a permanent fix. For hamstring tendinopathy, the relief window varies widely. Some people get weeks of benefit, others several months. The injection is best thought of as a tool that buys time for rehabilitation to work, not as a standalone treatment. If the underlying cause (weakness, overuse, biomechanical issues) isn’t addressed, the pain often returns once the cortisone wears off.
Repeat injections at the same site are generally limited to a few per year, with adequate spacing between them. Each additional injection carries a slightly higher cumulative risk of tissue changes like fat thinning or tendon weakening, which is why most providers emphasize using the pain-free window to build strength and correct whatever led to the injury in the first place.