Cortisone Shot Side Effects: The Common, the Rare and the Flare

The needle itself takes about ten seconds. Then comes the strange part: your knee feels wonderful for four hours, thanks to the numbing medicine mixed into the syringe, and then, sometime around midnight, it aches worse than it did in the waiting room. Nobody warned you about that.

That midnight ache has a name, a mechanism, and an expiration date. So does the flushed face some people notice the next morning, and the blood sugar spike that catches people with diabetes off guard. Corticosteroid injections have been a workhorse of pain care since the 1950s, and physicians reach for them millions of times a year for arthritic knees, frozen shoulders, and inflamed tendons.

What patients rarely get is an honest map of what happens in the hours, days, and months afterward. Here is that map, the common, the rare, and the flare, drawn from what the evidence actually shows.

What's actually in a cortisone shot?

Despite the everyday name, most “cortisone” shots don’t contain cortisone itself. They contain a synthetic corticosteroid: a lab-made cousin of cortisol, the hormone your adrenal glands produce naturally. Clinicians often mix in a fast-acting local numbing medicine, which is why the joint can feel almost eerily good on the drive home.

The steroid isn’t a painkiller in the usual sense. It works by quieting the local inflammatory machinery: fewer inflammatory chemicals released, less swelling pressing on nerve endings, less heat and stiffness in the tissue. That’s a slower process than numbing a nerve, which explains the timeline most people experience. The anesthetic works within minutes and fades within hours. The steroid typically begins working over two to seven days, according to the Mayo Clinic, and its effect can last weeks to months.

That gap between the anesthetic wearing off and the steroid kicking in matters. It’s where the notorious “cortisone flare” lives, and it’s why the first 48 hours after an injection are the noisiest, and the most misunderstood. Understanding that the shot is an anti-inflammatory with a delayed onset, not an instant fix, reframes almost every side effect that follows.

What are the most common cortisone shot side effects?

The honest headline: most side effects are local, mild, and measured in days. Here’s how the common ones typically play out.

Side effect	Roughly how often	Typical course
Soreness or bruising at the injection site	Very common	Fades within 2–3 days
Cortisone flare (temporary pain increase)	Estimates range from a few percent to roughly 1 in 4	Starts within 24 hours, settles by 48–72 hours
Facial flushing and warmth	Up to about 15%, more often reported by women	Appears within 1–2 days, resolves in a few days
Blood sugar rise	Common in people with diabetes	Hours to about a week
Trouble sleeping, restlessness	Occasional	A night or two
Skin lightening or dimpling near the site	Uncommon	Weeks to months; occasionally lasting

Notice what’s missing from that table: anything catastrophic. Serious complications exist, we’ll get to them, but they sit far down the probability curve. The Cleveland Clinic and NHS both describe local injections as generally well tolerated precisely because the medicine is concentrated in one spot rather than circulating through the whole body at high levels, the way long-term steroid tablets do.

What is a cortisone flare, and why does pain get worse before it gets better?

The flare is the side effect most likely to send a worried patient to a search engine at 2 a.m. It feels like betrayal: you got the shot to reduce pain, and the pain doubled.

The mechanism is almost mechanical. Many injectable corticosteroids are suspensions of microscopic crystals: that’s what makes them long-acting, dissolving slowly over weeks. In some people, those crystals briefly irritate the joint lining or surrounding tissue before they begin their anti-inflammatory work. Add the numbing medicine wearing off, and the result is a pain spike that typically begins within 24 hours and peaks on day one or two.

The reassuring part is the clock. A true flare settles within 48 to 72 hours, and ice plus relative rest is usually all it needs. What deserves attention is anything that breaks that pattern:

• Pain that keeps climbing past the 48-hour mark rather than easing
• Fever or chills
• Redness or warmth that spreads outward from the injection site
• A joint that becomes too painful to move or bear weight on

Those features point away from a flare and toward possible infection, rare, but urgent. The distinction is simple to remember: a flare is loud but brief and stays local. An infection escalates and makes you feel unwell all over. When in doubt, call the office that gave you the injection; this is exactly the question they expect.

Why is my face hot and red after a cortisone shot?

A day or two after the injection, some people look in the mirror and see a face that appears sunburned, warm, pink, sometimes spreading down the neck and chest. It can feel alarming precisely because it seems so disconnected from the knee or shoulder that got the shot.

The connection is the bloodstream. Even a locally injected steroid gets partially absorbed into circulation, and corticosteroids can temporarily dilate small blood vessels in the skin. The result is flushing: harmless, sometimes accompanied by a general feeling of warmth, and reported in up to roughly 15 percent of patients in some series, more often by women. It usually appears within 24 to 48 hours and fades within a few days without treatment.

A cool compress helps with comfort, and it’s sensible to skip alcohol and very hot showers while it lasts, since both widen blood vessels further. Flushing on its own is not an allergic reaction. A true allergic response looks different, hives, itching, swelling of the lips or tongue, wheezing, dizziness, and warrants immediate medical attention, though genuine allergy to these injections is uncommon.

One practical note: because flushing can arrive after you’ve left the clinic and stopped thinking about the shot, patients sometimes attribute it to a virus or a new soap. If it shows up within two days of an injection, the injection is the likelier explanation.

Do cortisone shots raise blood sugar? What people with diabetes should know

This may be the most underappreciated side effect on the list, because it’s invisible unless you’re checking. Corticosteroids prompt the liver to release more glucose and make muscle and fat cells temporarily less responsive to insulin. For most people, the pancreas compensates and nothing noticeable happens. For people with diabetes, blood sugar can climb within hours of the injection and stay elevated for several days, occasionally up to a week.

The rise varies with the preparation, the amount used, and where it was injected, so there’s no universal number to expect. What the evidence supports is a plan rather than a prediction:

• Tell the injecting clinician you have diabetes before the procedure: it may influence their choices.
• Check your glucose more frequently for at least three to five days afterward.
• Know in advance what reading should trigger a call to your diabetes care team, and ask whether your usual regimen needs a temporary adjustment.
• Stay hydrated and keep meals consistent while levels settle.

People with prediabetes or those who haven’t been tested recently occasionally discover elevated glucose this way, which is worth mentioning to a primary care clinician even after levels normalize. The effect is temporary, but it’s a real physiological event, not a rounding error, and planning for it beats being surprised by it.

Skin changes after a cortisone shot: lightening, thinning, and small dents

Weeks after an injection, long after the soreness is forgotten, a pale patch or a subtle dimple can appear near the injection site. This delayed timing makes it one of the more disorienting side effects, because patients often don’t connect it to the shot at all.

Two separate things can happen. The first is hypopigmentation: the steroid can temporarily reduce pigment production in nearby skin cells, leaving a lighter patch. This is more visible in deeper skin tones, and while it often fades over months, it occasionally persists. The second is fat atrophy: the steroid can shrink the small cushion of fat under the skin, leaving a slight depression or dent.

Both are more likely with shallow injections, around the elbow for tennis elbow, in the hand or wrist, near the heel, where the medicine sits close to the surface, and less likely with deep joint injections into a knee or hip. Neither is dangerous. Neither affects whether the shot worked. But if the injection site is cosmetically visible, it’s a fair question to raise beforehand, and clinicians can sometimes adjust technique or placement accordingly.

If a lightened patch or dimple appears, photograph it and mention it at your next visit. Most soften with time. What these changes are not: a sign of infection, cancer, or anything spreading. They are a local, slow-motion footprint of where the medicine sat.

How long does cortisone stay in the body after a shot?

The short answer has two layers, because “in the body” and “still working” are different questions.

Physically, the injected steroid forms a small depot in the tissue and dissolves gradually. Shorter-acting, more soluble preparations clear within days; longer-acting, crystal-based preparations release medicine over roughly two to six weeks. Once absorbed into the bloodstream, the drug itself is metabolized and cleared fairly quickly, which is why systemic effects like flushing and blood sugar elevation typically resolve within days, not months.

Functionally, the story runs longer. The anti-inflammatory effect can outlast the medicine’s physical presence considerably, because calming an inflamed joint can interrupt the cycle of swelling, irritation, and more swelling. The Mayo Clinic notes relief may last weeks to several months, and some patients get longer stretches, particularly when the injection is paired with physical therapy or activity changes that address the underlying mechanics.

Two practical implications follow. First, don’t judge the shot too early: its full effect may not be apparent for a week. Second, if you’re scheduled for surgery, dental work, or lab tests, mention the recent injection; a steroid still dissolving in your tissue is relevant medical information. And if relief consistently fades after only a couple of weeks, that pattern is worth discussing, because it may signal that the diagnosis or treatment plan needs a second look rather than simply another needle.

What should you not do after a cortisone shot?

The instructions after an injection are short, but each one exists for a reason.

Don’t stress the area for the first day or two. Relative rest, normal walking is fine, a five-mile run is not, protects irritated tissue and gives the flare window a chance to pass quietly. For tendon injections in particular, many clinicians advise easing back into heavy loading over one to two weeks, because steroids can transiently soften tendon tissue.

Don’t be fooled by the numb hours. The anesthetic can make a damaged joint feel invincible for an afternoon. It isn’t. Injuries happen when people test the “cured” joint before the numbing wears off.

Don’t soak the site immediately. Keep the area clean and dry for about 24 hours; showers are fine, but skip pools, hot tubs, and baths that first day to reduce infection risk at the puncture site.

Don’t ignore your glucose if you have diabetes. As covered above, check more often for several days.

Don’t apply heat to a flaring joint. Ice for 15 to 20 minutes at a time is the better tool for the first couple of days; heat can amplify inflammation-related pain.

One thing you generally don’t need to avoid: an occasional alcoholic drink. The NHS notes there’s no direct interaction with local steroid injections, though moderation is sensible while flushing or sleep disturbance is in play.

The rare but serious risks: infection, tendon rupture, and bone damage

Now the fine print, worth knowing precisely because it’s rare, so you can recognize it rather than fear it.

Joint infection is the complication clinicians watch for most vigilantly. When bacteria enter a joint, the result is septic arthritis: escalating pain, swelling, warmth, fever, and a joint that resists any movement. Commonly cited estimates put the risk in the range of one in tens of thousands of injections when sterile technique is used. It is a medical emergency, same-day evaluation, not a wait-and-see situation.

Tendon weakening and rupture explains a piece of injection etiquette you may notice: physicians generally inject around inflamed tendons rather than into them, and they approach the Achilles and patellar tendons, the body’s heavy load-bearers, with particular caution. Repeated steroid exposure can degrade tendon structure, and rupture, while uncommon, is a serious outcome.

Bone effects are rarer still. Avascular necrosis, loss of blood supply to a segment of bone, usually near a hip or shoulder, has been associated with steroid exposure, far more often with long-term oral use than with occasional injections. Temporary weakening of nearby bone has also been described.

Nerve irritation can occur if the needle passes close to a nerve, usually causing transient tingling or numbness that resolves on its own.

None of this argues against a well-indicated injection. It argues for getting one from an experienced clinician, in a clean setting, for a clear diagnosis, and for taking fever after an injection seriously, every time.

Do repeated cortisone shots damage cartilage? What the evidence actually shows

This is where honest reporting matters, because the evidence is more nuanced than either “perfectly safe” or “destroys your joint.”

The study most often cited is a two-year randomized trial in people with knee osteoarthritis, published in 2017, in which one group received a steroid injection every three months on a fixed schedule and the other received placebo injections. The steroid group lost slightly more cartilage thickness over two years, a modest difference of roughly a tenth of a millimeter, and, notably, reported no better pain relief than the placebo group. Observational studies have raised similar cautions, though observational data can’t cleanly separate the effect of the shots from the severity of the arthritis that prompted them.

What can be reasonably concluded: injecting a joint on a rigid schedule, flare or no flare, is hard to justify: you accrue the cartilage question without a proven pain payoff. An occasional injection for a genuine, disabling flare sits on much firmer ground, especially when it buys a window to do physical therapy, strengthen supporting muscles, or manage weight-bearing load: the interventions with the strongest long-term evidence in osteoarthritis.

The most useful way to think about it: a cortisone shot is a bridge, not a destination. If you find yourself needing the bridge every few months indefinitely, that’s a signal to revisit the plan with your clinician, not simply to keep crossing.

Where is the most painful place to get a cortisone shot?

Patients compare notes on this, and the folklore is largely accurate. The injections most consistently described as painful share two features: densely packed nerve endings and tight, unyielding tissue with nowhere for the fluid to go.

By that logic, the usual winners are the sole of the foot, plantar fascia injections for heel pain have a fearsome reputation, and the palm of the hand, where injections for trigger finger or thumb arthritis meet skin that is thick, tightly anchored, and exquisitely sensitive. Injections near fingertips and around the nail beds rank similarly. Large joints like the knee or shoulder, by contrast, are roomy enough that many patients report the shot feels like a firm pressure and a brief sting.

The discomfort is real but short, typically seconds of sharp pain, then an ache that fades over a day or two. And clinicians have tools to blunt it: cold numbing spray on the skin, smaller needles, slower injection of the fluid, numbing medicine mixed into the syringe, and image guidance that places the needle precisely on the first pass.

Spinal injections deserve a separate mention, since patients often assume they top the pain chart. In practice they’re performed with local anesthetic and usually imaging guidance, and many patients describe pressure more than pain. If needle anxiety is significant for you, say so beforehand: it changes how the clinician approaches the procedure, and that conversation is entirely routine.

How many cortisone shots can you safely get?

There’s no biologically fixed ceiling written into your joints, but there is a widely observed rule of prudence. The Mayo Clinic’s guidance is representative: injections into the same joint are generally spaced at least six weeks apart and limited to about three or four per year.

The logic stacks several concerns together. Cartilage, as discussed, may fare worse with frequent repeated exposure. Tendons and ligaments near the injection site can weaken. Skin and fat changes become more likely with repetition. And although each shot delivers only a modest systemic dose, frequent injections add up, with enough cumulative exposure, corticosteroids can temporarily suppress the body’s own cortisol production and nudge blood pressure, glucose, and bone density in unwelcome directions.

There’s also a clinical logic that has nothing to do with toxicity. If a joint needs injections every couple of months just to stay functional, the shots are managing a symptom while the underlying problem advances. That pattern usually means it’s time to widen the conversation: physical therapy, activity modification, bracing, other medication classes, or, for advanced joint disease, a surgical consultation.

Diminishing returns are part of the same signal. Many patients notice each successive injection helps a little less or for a shorter stretch. That’s not imagination; it often reflects progressing disease. A good clinician treats injection frequency as diagnostic information, not just a scheduling question, and patients can, too.

The systemic surprises: sleep, mood, periods, and blood pressure

Because the medicine partially enters the bloodstream, a local shot can produce brief whole-body effects that catch patients off guard, mostly because nobody mentioned them.

Sleep and energy. Corticosteroids are chemically related to the hormone that governs your morning alertness surge, so a wired, restless night or two after an injection is a recognized effect. It passes on its own; skipping late-day caffeine helps in the meantime.

Mood. Some people notice feeling unusually energized, irritable, or emotionally amplified for a day or two. With a single local injection this is typically mild and self-limiting: a far cry from the mood effects seen with long-term, high-dose oral steroids.

Menstrual changes. A temporarily irregular, early, late, or heavier period after a steroid injection is a documented and underdiscussed effect, likely reflecting the hormone system’s brief recalibration. One altered cycle after a shot is generally not concerning; persistent changes warrant a routine check-in.

Blood pressure. A modest, temporary rise is possible, because corticosteroids influence how the body handles salt and fluid. People with hypertension may want to check their readings for a few days afterward.

The common thread across all four: onset within days of the shot, resolution within days after. Anything that lingers well beyond a week has probably outlived the injection’s systemic footprint and deserves its own evaluation rather than being filed under “the shot.”

When should you see a doctor after a cortisone shot?

Most post-injection questions can wait for a phone call during office hours. A few cannot. Here’s how to sort them.

Seek care the same daycall the injecting clinic, or go to urgent or emergency care if you can’t reach them, for:

• Fever or chills after the injection
• Pain that intensifies beyond 48 hours instead of easing
• Redness, warmth, or swelling spreading outward from the site
• A joint too painful to move or bear weight on
• Signs of allergic reaction: hives, facial or tongue swelling, wheezing, lightheadedness

Call within a day or two for blood sugar readings that stay high despite your usual management, drainage or bleeding from the injection site, new numbness or tingling that isn’t fading, or a blood pressure jump that concerns you.

Mention at your next routine visit: skin lightening or dimpling, a changed menstrual cycle that has since normalized, or the sense that the shot helped less than previous ones.

The pattern behind the triage is worth internalizing. Expected side effects arrive early, stay local or mild, and improve on a predictable clock. Red flags escalate, spread, or make you feel systemically unwell. If your symptoms are moving in the wrong direction after 48 hours, don’t talk yourself out of the phone call, clinicians would far rather rule out an infection at hour 50 than treat one at day five.

Frequently asked questions

How long does cortisone stay in the body after a shot?

The injected steroid typically dissolves from the injection site over days to weeks, longer-acting preparations release medicine for roughly two to six weeks, while systemic effects like flushing or elevated blood sugar usually resolve within days. The pain-relieving benefit can outlast the drug itself, lasting weeks to several months, because interrupting inflammation can break the cycle that was driving the pain.

What should you not do after a cortisone shot?

Avoid strenuous use of the injected area for 24 to 48 hours, and ease back into heavy loading over one to two weeks after tendon injections. Skip pools, hot tubs, and baths for the first day to protect the puncture site, use ice rather than heat if a flare develops, and don’t overexert the joint while the numbing medicine is masking pain. People with diabetes should check glucose more often for several days.

Where is the most painful place to get a cortisone shot?

The sole of the foot and the palm of the hand are the injections patients most consistently describe as painful, because both areas have dense nerve endings and tight tissue with little room for injected fluid. Large joints like the knee or shoulder usually hurt less. The sharp pain lasts seconds, and numbing spray, smaller needles, and image guidance can all reduce it, ask beforehand if needles worry you.

What are five common side effects of steroid injections?

The five most common are soreness or bruising at the injection site, a temporary pain flare in the first 24 to 48 hours, facial flushing and warmth, a blood sugar rise lasting several days in people with diabetes, and a night or two of restlessness or poor sleep. All five typically resolve on their own within days and don’t affect whether the injection ultimately works.

How long does a cortisone flare last?

A typical cortisone flare begins within 24 hours of the injection, peaks on the first or second day, and settles within 48 to 72 hours. Ice and relative rest are usually enough to manage it. Pain that keeps worsening past 48 hours, or a flare accompanied by fever, spreading redness, or a joint that won’t bear weight, is not a flare pattern and needs same-day medical evaluation to rule out infection.

Can a cortisone shot raise your blood pressure?

Yes, a modest and temporary rise is possible, because corticosteroids influence how the body handles salt and fluid. With a single local injection the effect is usually small and resolves within days as the medicine clears. People with existing hypertension may want to check readings at home for a few days afterward and contact their clinician if numbers stay unusually high beyond a week.

Can you drink alcohol after a cortisone shot?

Generally yes, in moderation: the NHS notes no direct interaction between alcohol and local steroid injections. That said, alcohol widens blood vessels, which can worsen post-injection facial flushing, and it can compound the sleep disruption some people experience for a night or two after a shot. If you’re monitoring blood sugar after the injection, remember alcohol can also complicate glucose readings.

How long does it take for a cortisone shot to work?

The steroid typically begins reducing inflammation within two to seven days, with full effect often apparent by the end of the first week. The immediate relief many people feel on the day of the shot comes from numbing medicine mixed into the injection, which wears off within hours, so a temporary return of pain before the steroid kicks in is expected and doesn’t mean the shot failed.

How many cortisone shots can you get in a year?

Most clinicians limit injections into the same joint to about three or four per year, spaced at least six weeks apart, per Mayo Clinic guidance. The limit reflects concerns about cartilage, tendon, and skin changes with frequent repetition, plus cumulative systemic exposure. If a joint needs injections that often just to function, that pattern itself signals the treatment plan should be broadened rather than the shots simply repeated.

Can a cortisone shot affect your menstrual period?

Yes, temporarily. A period that arrives early, late, heavier, or irregularly after a steroid injection is a documented effect, likely reflecting a brief recalibration of the hormone system as the medicine circulates. One altered cycle after a shot generally isn’t cause for concern and resolves on its own. Menstrual changes that persist beyond a cycle or two deserve their own evaluation, since they’ve likely outlasted the injection’s effect.

References

• Steroid injections: NHS
• Hydrocortisone injections: NHS
• Steroids: MedlinePlus

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.