A cortisone shot typically contains two main ingredients: a synthetic corticosteroid that reduces inflammation and a local anesthetic that numbs the area. The exact formulation varies depending on the joint being treated and the condition being addressed, but those two components make up the bulk of what’s in the syringe.
The Steroid Component
Despite the name “cortisone shot,” the injection rarely contains actual cortisone. Instead, it uses a more potent synthetic version of the hormone your adrenal glands naturally produce. The most common options are methylprednisolone acetate, triamcinolone acetonide, betamethasone, and dexamethasone. These are all lab-made compounds designed to mimic cortisol’s anti-inflammatory effects but at much higher potency and with longer-lasting results.
These steroids vary in strength and duration. Hydrocortisone is the weakest and shortest-acting, while betamethasone sits at the high end for both potency and duration. Some formulations combine a short-acting compound with a long-acting suspension in the same syringe. This gives you faster initial relief while the longer-acting ingredient kicks in and sustains the effect over weeks. Potency is measured relative to hydrocortisone, and the stronger agents require smaller doses to achieve the same result.
The Numbing Agent
Most cortisone shots also include a local anesthetic mixed into the syringe. The two most common are lidocaine and bupivacaine. Lidocaine works quickly and wears off within a couple of hours. Bupivacaine takes a bit longer to start working but lasts several hours longer. In some cases, providers use ropivacaine as an alternative.
The anesthetic serves two purposes. First, it reduces the pain of the injection itself and provides immediate, short-term relief in the area. Second, it acts as a diagnostic tool: if your pain disappears within minutes of the shot, it confirms that the provider injected the right spot. The steroid itself takes a day or two (sometimes longer) to start working, so any immediate relief you feel is the numbing agent doing its job.
Typical volumes of anesthetic are small, often just 0.5 to 2 mL of bupivacaine or a similar amount of lidocaine, depending on the size of the joint.
How the Steroid Works in Your Body
Once injected, the corticosteroid tackles inflammation through several pathways. It limits the widening and leaking of tiny blood vessels at the injury site, which is what causes swelling and redness. It also blocks immune cells from flooding into the area and reduces the release of chemical signals called prostaglandins that amplify pain and inflammation. On top of that, it inhibits enzymes that break down tissue indiscriminately around an injury, which helps protect healthy surrounding structures.
The net effect is a significant reduction in swelling, pain, and stiffness at the injection site. Relief typically lasts anywhere from a few weeks to several months, depending on the steroid used and the severity of the condition being treated.
How Doses Differ by Joint Size
The amount of steroid in the syringe changes based on where it’s going. Large joints like the knee or shoulder receive a higher dose, while smaller joints in the hand or foot get considerably less. Soft tissue injections for conditions like tennis elbow or plantar fasciitis also use lower amounts. Your provider selects both the type of steroid and the dose based on the joint, the diagnosis, and your history with previous injections.
The total volume of fluid in a cortisone shot is small, usually just a few milliliters combining the steroid and anesthetic together. For a knee injection, you might receive around 1 to 2 mL of steroid plus 1 to 2 mL of anesthetic. For a finger joint, the total volume could be under 1 mL.
What Else Might Be in the Syringe
Beyond the steroid and anesthetic, the formulation includes inactive ingredients that keep the medication stable and injectable. Many corticosteroid preparations are suspensions, meaning tiny crystite particles are suspended in liquid rather than fully dissolved. This is why the vial often needs to be shaken before drawing up the medication. Some formulations contain preservatives like benzyl alcohol, and others include buffering agents to adjust the pH so the injection is less irritating to tissue.
These inactive ingredients are worth knowing about if you have known allergies. Rare allergic reactions to cortisone shots are usually triggered by a preservative or the anesthetic rather than the steroid itself. If you’ve had a reaction to a local anesthetic at the dentist, for example, that’s worth mentioning before getting a cortisone shot.
Limits on How Often You Can Get One
Because the steroid component can affect surrounding tissue over time, there are limits on how frequently you can receive cortisone shots in the same joint. Repeated injections carry a risk of cartilage damage, and the exact number your provider will allow depends on the specific joint, your diagnosis, and how you’ve responded to previous shots. Most providers space injections at least several months apart and cap the total number per year, though there’s no single universal rule that applies to every situation.