Written by Aisling Moran BSc (Hons)
30th Mar 2023 • 4 minute read
Dr Noel Young
Reviewed by
Dr Noel Young MBBS BSc, Medicine

Cortisol is a stress hormone that’s produced by your body. It’s essential for your health, but too much cortisol can cause problems, ranging from anxiety to diabetes. When high cortisol causes symptoms and conditions, it’s known as Cushing’s syndrome. Here's how to spot the signs of high cortisol, how to test your levels, and what you can do to lower them.

What is cortisol?

Cortisol is a hormone that plays a key role in how you respond to stress. For example, if you’re in danger, your body releases adrenaline and cortisol hormones. These increase your heart rate and energy levels so you can quickly react if you're in danger.

On top of helping you respond to stress, cortisol also helps:

  • regulate your blood pressure
  • regulate the metabolism of carbohydrates, fats, and proteins 
  • regulate the effects of insulin — a hormone that controls your blood sugar levels
  • reduce inflammation
  • maintain your sleep-wake cycle

So while cortisol often gets a bad reputation, it’s important for your health and survival. It only becomes problematic if your cortisol levels are high for long periods of time.

What are the symptoms of high cortisol levels?

Regular and prolonged exposure to high cortisol levels can wreak havoc on your body. Over time this can cause Cushing’s syndrome. Some of the most common signs of high cortisol levels include:

Over time, high cortisol can put you at risk of heart disease, osteoporosis, diabetes, and poor mental health.

What causes high cortisol levels?

Many things can cause high cortisol levels, including:

  • physical and emotional stress — your body can't gauge the seriousness of a stressful situation, so something simple like a traffic jam can kick-start your stress response system, as can being ill with a cold
  • medication — certain medications like corticosteroids and oral contraceptives might increase your cortisol levels
  • oestrogen — high oestrogen levels in women, for example, in pregnancy, is linked to raised cortisol levels
  • an adrenal gland tumour — your adrenal glands produce cortisol, so any issues with them can affect your cortisol levels
  • a pituitary gland issue — an overactive pituitary gland stimulates your adrenal glands to make too much cortisol
  • malnutrition — for example, if you suffer from an eating disorder like anorexia nervosa

Conditions like depression, diabetes, PCOS, and alcoholism are also linked to high cortisol levels.

How to test your cortisol levels

A blood, saliva, or urine test can be done to measure your cortisol levels. Depending on the cause, your GP might sometimes arrange a cortisol test, most commonly a blood test.

Cortisol blood test

A cortisol blood test is usually done in the morning when your cortisol levels are at their highest. Cortisol levels tend to fall as the day progresses, reaching their lowest point at night before bed.

Cortisol urine test

A cortisol urine test involves collecting all of your urine over the course of a day. This can help to show how your cortisol levels change throughout the day. 

How to lower your cortisol levels

If your cortisol levels are high, how you lower them will depend on the underlying cause. If it’s because of issues with your pituitary gland, adrenal glands, or medication, you’ll need to work with your GP or health professional to lower them. If it’s because of chronic stress, there are lots of lifestyle changes you can make to lower your stress levels:

  • enjoy yourself (a lot) — do something you love every day, like dancing or listening to music, to improve your mood
  • practice mindfulness — for example, daily meditation or yoga
  • connect with your friends, family, and even your pet — a strong social support system is important for your mental health
  • make sleep a priority — do your best to get at least 7 hours of sleep every night
  • break a sweat — aim for at least 75 vigorous minutes of activity or 150 minutes of moderate aerobic activity each week
  • eat a healthy diet — aim for a lot of fruit, vegetables, whole grains, nuts, seeds, and oily fish
  • breathing exercises — for example, deep nose breathing or counting breaths
  • try a supplementomega-3, vitamin B-complex, magnesium, L-theanine, lemon balm, valerian root, and ashwagandha are linked to lower cortisol levels (it's a good idea to work with a health professional when starting a supplement, particularly if you're on any medication)