Decoding the Injection: What is a Steroid Shot Made Of?

October 7, 2025 •

4 min read

In a given year, trochanteric bursitis is a leading cause of hip pain in adults, and steroid injections can be curative in up to 83% of cases for other conditions like de Quervain tenosynovitis [1.7.1]. So, what is a steroid shot made of? It's a combination of powerful medications designed for targeted relief.

Quick Summary

A steroid shot primarily consists of a synthetic corticosteroid to reduce inflammation and often a local anesthetic for immediate pain relief, delivered in a sterile liquid suspension [1.2.1, 1.2.3].

Key Points

Primary Component: The main ingredient is a corticosteroid, a synthetic drug that mimics the body's natural anti-inflammatory hormone, cortisol [1.9.2].
Dual-Action Pain Relief: Many shots include a local anesthetic like lidocaine or bupivacaine to provide immediate pain relief while the slower-acting steroid takes effect [1.2.1, 1.4.4].
Inactive Ingredients: The solution contains excipients like sterile water, preservatives (e.g., benzyl alcohol), and suspending agents to ensure stability and safety [1.3.1, 1.3.5].
Mechanism of Action: Steroids work by blocking the production of inflammatory chemicals at the cellular level, which reduces swelling, stiffness, and pain [1.9.3].
Variable Formulations: Different types of corticosteroids (e.g., Triamcinolone, Methylprednisolone) are used depending on the specific condition and the desired duration of the anti-inflammatory effect [1.5.1, 1.6.4].

Inside the Vial: The Core Components of a Steroid Shot

When a healthcare provider recommends a steroid injection for conditions like arthritis, tendonitis, or bursitis, the goal is to deliver potent anti-inflammatory medication directly to the source of pain [1.5.4, 1.5.5]. These injections, also known as cortisone shots, are complex formulations. A typical steroid shot is a mixture that includes an active corticosteroid, a numbing agent, and various inactive ingredients that ensure the medication is safe and stable [1.2.1, 1.3.5].

The Active Ingredient: Corticosteroids

The primary component is a synthetic corticosteroid, which is a powerful drug that mimics cortisol, a hormone naturally produced by the body's adrenal gland [1.9.2]. Its main job is to suppress inflammation and the immune system's response in a specific area [1.9.2, 1.9.4]. By reducing inflammation, the injection helps to alleviate pain, swelling, and stiffness [1.9.1].

There are several types of corticosteroids used in these injections, chosen based on the condition being treated and the desired duration of action [1.5.2]. Common examples include:

Triamcinolone (Kenalog®) [1.5.1]
Methylprednisolone (Depo-Medrol®) [1.5.1]
Betamethasone (Celestone Soluspan®) [1.5.1]
Dexamethasone [1.2.1]

These drugs work at a cellular level, diffusing through the cell membrane to reduce the production of inflammatory substances like prostaglandins and leukotrienes [1.9.3].

The Supporting Agent: Local Anesthetics

Many steroid injections are prepared as a cocktail containing a local anesthetic [1.2.3, 1.2.4]. This addition serves two purposes: it provides immediate pain relief at the injection site, as the corticosteroid can take several days to become fully effective, and it can help a physician confirm diagnostically that they have targeted the correct source of pain [1.4.4, 1.7.1].

Commonly used local anesthetics include:

Lidocaine [1.2.1]
Bupivacaine [1.2.1]

Surveys of physicians show that lidocaine is the most frequently used anesthetic in these preparations [1.4.2].

The Vehicle: Inactive Ingredients (Excipients)

Beyond the active drugs, a steroid injection contains several inactive ingredients, also called excipients. These substances are crucial for the medication's stability, safety, and effectiveness. They create the sterile liquid suspension that carries the active components.

Examples of these excipients include:

Water for Injection: A sterile solvent that forms the base of the injection [1.3.1, 1.3.3].
Preservatives: Such as benzyl alcohol, which prevents microbial growth in multi-dose vials [1.3.1, 1.3.5].
Suspending Agents: Ingredients like carboxymethylcellulose or polysorbate 80 keep the steroid crystals evenly distributed throughout the liquid [1.3.5].
Buffers: Compounds like sodium citrate are used to adjust and maintain the pH of the solution to ensure it is safe for injection [1.3.1, 1.3.3].

A Comparison of Common Injectable Steroids

Clinicians choose between different corticosteroids based on their potency and solubility, which affects how long they last and where they can be safely used [1.6.4]. Here’s a comparison of two common options:


Feature	Methylprednisolone (Depo-Medrol®)	Triamcinolone (Kenalog®)
Potency	Both are intermediate-acting glucocorticoids, approximately five times stronger than natural cortisol [1.6.4].	Both are intermediate-acting glucocorticoids, approximately five times stronger than natural cortisol [1.6.4].
Common Uses	Used for a wide range of inflammatory conditions, including asthma, allergies, and arthritis [1.6.3].	Often used for osteoarthritis, skin conditions like alopecia or keloids, and allergies [1.6.2, 1.6.3].
Solubility & Onset	It is more soluble, which means it may be absorbed a bit faster [1.6.4]. This makes it a safer choice for injections near tendons where skin thinning is a concern [1.6.4].	Less soluble, which contributes to a potentially longer duration of action at the injection site [1.6.4].
Duration	The biological half-life is around 12-36 hours, but clinical effects can last for weeks [1.6.4].	The biological half-life is around 12-36 hours, but clinical effects can last for weeks [1.6.4].

Potential Side Effects and Considerations

While generally safe, steroid injections carry potential risks. It's common to experience a temporary 'cortisone flare,' which is an increase in pain for a day or two after the injection before the steroid takes effect [1.8.3].

Local side effects at the injection site can include:

Pain or swelling [1.8.3]
Skin thinning or atrophy [1.7.1]
Loss of skin color (depigmentation) [1.8.2]
Infection (rare, with a risk of about 1 in 1,000) [1.7.1]

Systemic side effects are less common with injections compared to oral steroids but can occur [1.8.2]. These include temporary elevation of blood sugar levels (an important consideration for diabetics), facial flushing, insomnia, and mood changes [1.8.1, 1.8.3]. To minimize risks, healthcare providers typically limit the number of injections a person receives in a single area per year [1.8.4].

Conclusion

A steroid shot is a carefully formulated medical treatment, not a single substance. It is primarily composed of a powerful anti-inflammatory corticosteroid like triamcinolone or methylprednisolone, which is often mixed with a fast-acting local anesthetic such as lidocaine [1.2.1, 1.2.2]. These active drugs are suspended in a sterile solution containing various excipients that ensure the product is stable and safe for administration [1.3.1, 1.3.5]. This combination allows for targeted, effective relief from pain and inflammation for a variety of musculoskeletal conditions, providing a window for healing and rehabilitation [1.9.1].

For more information, you can review this guide on Cortisone Shots from the Mayo Clinic.

Frequently Asked Questions

Yes, the terms are often used interchangeably. Cortisone is a specific type of corticosteroid, and these injections deliver a dose of corticosteroid medication to a targeted area [1.9.1, 1.9.4].

While the local anesthetic provides immediate numbing, the corticosteroid itself typically begins to work within two to seven days [1.2.1]. Some people report gradual pain reduction over several days or weeks [1.9.2].

A steroid shot delivers medication directly to a localized area of inflammation, which minimizes exposure to the rest of the body [1.9.4]. Oral corticosteroids affect the entire body and are more likely to cause systemic side effects [1.8.2].

The duration of pain relief is variable, ranging from a few days to several months or longer. A typical effective duration is around three to six months [1.2.1, 1.9.1].

A cortisone flare is a temporary increase in pain and swelling at the injection site that can occur in the first 24 to 48 hours after the injection. It happens before the steroid's anti-inflammatory effects begin to work [1.8.1, 1.8.3].

Yes, different types of corticosteroids like methylprednisolone and triamcinolone have different potencies and are available in various concentrations. The doctor chooses the type and dose based on the patient's specific condition [1.5.2, 1.6.4].

A local anesthetic is often included for two main reasons: to provide immediate pain relief since the steroid can take days to work, and to help the physician confirm they have injected the correct area causing the pain [1.4.4, 1.7.1].