Cortisol vs Cortisone

Cortisol and cortisone are two closely related steroid molecules whose names are easy to mix up. Cortisol is the body's main active stress hormone, while cortisone is a related, largely inactive form that the body can convert to and from cortisol. This page compares them for general understanding.

What cortisol is

Cortisol is a steroid hormone made by the adrenal glands, which sit on top of the kidneys. It is often called the body's main stress hormone because its release rises in response to stress, but it does far more than that. Cortisol helps regulate metabolism, influences blood sugar, affects the immune response, and follows a daily rhythm — generally higher in the morning and lower at night. Its production is governed by signals from the brain and pituitary gland, forming a feedback loop. When clinicians measure "cortisol," they are usually looking at this biologically active hormone.

What cortisone is

Cortisone is a steroid closely related to cortisol. In the body, it is essentially an inactive partner: cortisone itself has little direct hormonal effect until it is converted into cortisol. The two interconvert through enzymes that switch cortisol to cortisone and back again, depending on the tissue. This conversion is one way the body manages how much active cortisol reaches different tissues. The word "cortisone" is also widely used in everyday language to describe certain steroid medications, which is a separate, medical use of the term and a common source of confusion.

How they relate

The relationship between cortisol and cortisone is a conversion partnership. Specific enzymes turn active cortisol into inactive cortisone in some tissues, and turn cortisone back into cortisol in others. This local control lets the body fine-tune how much active hormone is available in a given place, rather than relying only on the total amount circulating. Because they interconvert, the two are best thought of as different states of a closely related molecule — one active, one largely inactive — rather than as two unrelated substances.

How they compare side by side

The points below summarise commonly discussed differences. They describe general distinctions, not rules, and the entries here are illustrative; the biology varies by tissue and situation.

For background on these hormones, see the hormones index; for how the cortisol sample is collected and timed, see the blood tests overview. Related conditions appear in the conditions index, treatment context lives in the treatments index, and you can browse more side-by-side explanations in the comparisons index.

When each matters

The distinction matters most when reading about adrenal function or steroid medications. In clinical testing, cortisol is usually the molecule of interest because it is the active hormone, and its daily rhythm means timing of a sample is important. Cortisone matters more as part of the conversion system that controls how much active cortisol reaches tissues. The everyday medical use of "cortisone" for certain steroid treatments is a separate topic — what links them is the underlying chemistry. For a related theme of natural versus laboratory-made hormones, see progesterone vs progestin.

Common points of confusion

The most common confusion is treating cortisol and cortisone as the same word for the same thing; they are different molecules, one active and one largely inactive. A second is the everyday use of "cortisone" to mean steroid medications, which blends a chemical name with a treatment category. A third is assuming the body keeps them entirely separate — in reality the two interconvert, so they are linked rather than independent. Keeping the active hormone (cortisol) distinct from its inactive partner (cortisone) makes discussions of adrenal physiology much clearer, and a clinician can explain how either term applies in a specific situation.