Corticosteroid injections, commonly known as cortisone shots, are medical treatments designed to manage inflammation and pain throughout the body. These injections deliver a synthetic version of the naturally occurring hormone cortisol directly to an affected area. While they offer rapid relief, patients often have concerns about potential side effects, with hair loss being a particular worry. Understanding how these shots interact with the hair growth cycle is necessary to separate common concerns from actual risks.
Understanding Cortisone Shots
Cortisone shots contain corticosteroids, which are anti-inflammatory drugs chemically similar to cortisol, a hormone produced by the adrenal glands. By suppressing the immune system’s response in a targeted area, these compounds reduce swelling, redness, and pain. The injection often includes a local anesthetic for immediate symptom relief while the steroid takes a few days to exert its full effect.
These injections are a routine treatment for a variety of conditions, including musculoskeletal issues like arthritis, bursitis, and tendonitis. They are also employed in dermatology to treat localized inflammatory skin diseases, such as keloid scars, severe acne cysts, and the autoimmune disorder alopecia areata.
The goal of the injection is highly localized action, depositing the medication precisely where inflammation is occurring. While the medication is primarily concentrated at the injection site, a small amount does enter the bloodstream. Repeat injections or high doses can increase the systemic absorption, which then raises the potential for effects on other body systems.
Localized Hair Changes at the Injection Site
The most direct link between a cortisone shot and hair loss occurs when the steroid is injected into or near the scalp, or when a musculoskeletal injection is placed too superficially. This specific type of hair loss is localized to the area immediately surrounding the injection site. The primary mechanism responsible for this effect is known as subcutaneous fat atrophy.
Fat atrophy refers to the thinning or depression of the layer of fat beneath the skin, a known side effect of concentrated corticosteroid exposure. Corticosteroids can inhibit the synthesis of collagen and damage the underlying fat cells, causing the skin surface to sink inward and create a visible dimple or depression.
When this atrophy occurs on the scalp, the loss of the supporting fat layer can disrupt the blood supply and structural integrity necessary for healthy hair follicle function. This disruption can prematurely push the hair follicles into a resting state, leading to localized hair shedding.
The risk of this side effect is higher when less soluble steroid preparations are used or when the injection is administered superficially. This localized hair loss typically presents as a small, non-scarring patch of thinning hair directly over the atrophied area. Physicians take careful steps to minimize this risk by using precise injection techniques and appropriate steroid concentrations.
Systemic Effects and Generalized Hair Shedding
While localized injections are not intended to affect the entire body, frequent, high-dose, or prolonged use of any corticosteroid, including systemic forms like oral tablets, can potentially trigger widespread hair shedding. This generalized hair loss is related to a condition called Telogen Effluvium (TE).
TE is a temporary hair cycle disturbance where a higher-than-normal number of growing hairs prematurely enter the resting phase. The hair growth cycle consists of a long growth phase (anagen), a short transition phase (catagen), and a resting phase (telogen). Normally, only about 10 to 15% of hairs are in the telogen phase at any given time.
Systemic physiological stress induced by large doses of corticosteroids acts as a shock to the system. This shock causes a sudden, synchronous shift of hairs out of the anagen phase and into the telogen phase. The actual, noticeable shedding typically occurs about two to four months after the systemic trigger or the start of the high-dose treatment. The result is a diffuse thinning across the entire scalp, not just a bald spot.
The occurrence of TE from a single, localized cortisone shot is rare due to minimal systemic absorption. However, patients on long-term or frequent systemic steroid therapy, or those with individual sensitivity, are more likely to experience this generalized shedding.
Recovery and When to Consult a Physician
The prognosis for cortisone shot-related hair loss is favorable, with both types of shedding being temporary.
For the localized hair loss caused by subcutaneous fat atrophy, the depression and associated hair thinning often resolve spontaneously as the body breaks down and absorbs the concentrated steroid crystals. This recovery process is gradual, often taking between six months to one year, though it can sometimes last up to two years.
In cases of generalized hair shedding due to Telogen Effluvium, the hair loss stops once the systemic trigger, such as the high-dose steroid treatment, is removed or stabilized. The shedding phase typically resolves within three to six months after the causative event, and full hair regrowth usually occurs within six to twelve months.
Individuals should consult with a physician, preferably a dermatologist, if hair loss is severe, persistent beyond a year, or accompanied by other systemic symptoms. A specialist can confirm the diagnosis, rule out other causes of hair loss, and discuss options to support hair regrowth, if necessary.