Cortisol is a hormone that is mainly released at times of stress. Cortisol has many important functions in the body. Having the right cortisol balance is essential for human health and you can have problems if you produce too much or too little cortisol.

What is cortisol?

Cortisol is a steroid hormone that is produced by the adrenal glands, which sit on top of each kidney. When released into the bloodstream, cortisol can act on many different parts of the body and can help:

• the body respond to stress or danger
• increase the body’s metabolism of glucose
• control blood pressure
• reduce inflammation

Cortisol is also needed for the fight or flight response, which is a healthy, natural response to perceived threats. The amount of cortisol produced is highly regulated by your body to ensure the balance is correct.

What triggers the adrenal glands to produce cortisol?

Cortisol production by the adrenal glands is regulated by the pituitary gland. The pituitary is a pea-sized gland at the base of the brain that is sometimes referred to as the "master gland" because of its wider effects on the body.

When you wake up, exercise or you’re facing a stressful event, your pituitary gland reacts. It sends a signal to the adrenal glands to produce just the right quantity of cortisol.

What happens when you produce too much or little cortisol?

The body usually produces the right amount of cortisol. In a condition such as Cushing’s syndrome, it produces too much. In a condition such as Addison’s disease, it produces too little.

Symptoms of too much cortisol include:

• weight gain, particularly around the abdomen and face
• thin and fragile skin that is slow to heal
• acne
• for women, facial hair and irregular menstrual periods

Symptoms of not enough cortisol include:

• continual tiredness
• nausea and vomiting
• weight loss
• muscle weakness
• pain in the abdomen

If you experience any of these symptoms, your doctor may suggest you have a blood test to measure your cortisol levels.

What are corticosteroids?

If your body does not produce enough cortisol, your doctor may prescribe corticosteroids for you. Corticosteroids are synthetic versions of cortisol that can be used to treat a variety of conditions including:

• inflammatory conditions (such as asthma)
• Addison’s disease
• skin conditions (such as psoriasis)

Some people take anabolic steroids to build muscles, without a doctor’s prescription. This is risky. Anabolic steroids are different to corticosteroids.

Are there any side effects of corticosteroid therapy?

Because corticosteroids are powerful medications, side effects are quite common. These may include:

• thinning skin
• osteoporosis
• weight gain, especially around the face, and increased appetite
• high blood sugar or diabetes
• rapid mood changes, feeling irritable and anxious
• an increased chance of infections
• Cushing's syndrome
• eye conditions, such as glaucoma and cataracts
• depression or suicidal thoughts
• high blood pressure