Why does cortisone work?

Cortisone is an anti-inflammatory hormone. It's injected into areas that are inflamed - swollen joints, painful plantar fasciitis - or used systemically (e.g., allergy). It may also be used cutaneously as a cream (hydrocortisone) in the case of rashes. Sometimes it's a broader name given to corticosteroid injections, which are various types of steroid hormones.

Essentially, the drug utilizes the natural system of the body to alleviate pain caused by inflammation by getting rid of the inflammation.

Natural cortisone production

The adrenal gland naturally produces cortisone, which is then metabolized to cortisol, the major stress hormone in humans. A synthetic version of cortisone was developed after researchers noticed that women experienced alleviation of their rheumatoid arthritis during pregnancy (a state in which cortisol is not cleared as quickly). The cortisone injections, which are sometimes combined with local anesthetics to reduce pain, are used to treat adrenal insufficiency and inflammatory disorders, but hydrocortisone also plays a role in chemotherapy for cancer.

How cortisone exerts actions

Steroids like cortisone treat inflammation by decreasing the production of pro-inflammatory mediators in the body. The actions are carried out by its metabolite, cortisol. Briefly, this molecule binds to receptors in the cytoplasm of cells and then travels to the nucleus of the cell to affect DNA transcription. More specifically, cortisol is a glucocorticoid and binds the glucocorticoid receptor. The glucocorticoid complex translocates to the nucleus and binds the glucocorticoid response element to affect the expression of pro-inflammatory genes. Cortisol also has effects on metabolism and the immune response. 

 

We take advantage of their properties and inject them locally to increase their effects in that area (and some injections contain pain relievers that help) and systemically to give the system a boost. The hormone is metabolized to cortisol once it is in the body - the infamous stress hormone.

How cortisol affects inflammation

Specific actions of glucocorticoids such as cortisone in inflammation include blockade of the secretion of certain interleukins by macrophages, which reduces the number of circulating T cells and prevents B-cell proliferation. The production of lipocortin is stimulated, which prevents phosphatidyl choline from being converted to arachidonic acid. This blocks the synthesis and release of the pro-inflammatory mediators known as prostaglandins and thromboxanes by the enzyme cyclooxygenase (COX), which prevents vasodilation. The lack of arachidonic acid also blocks the actions of leukotrienes in the immune response.

Cortisone injections in local inflammation

Under normal conditions, the body regulates inflammatory responses via endogenous (i.e. produced by the body) hormones like cortisol. The endocrine system is stimulated by the stressors (there are many theories about inflammation and stress), which results in the secretion of hormones to counteract it. The actions of cortisol affect nearly every tissue and cell in the body. This is a systemic response. When the inflammation is localized, such as in plantar fasciitis, cortisone injections can help the body alleviate the inflammation at a more local level. Injection of the hormone into, for example, a swollen and inflamed joint can act on the cells in that area, reducing the inflammatory mediators and local inflammation. However, there are side effects due to the myriad actions of the molecule, which requires a limit on how often a person can be treated with the injections.