Low cortisol: what it means, the symptoms, and what it is not
Low cortisol explained: what it means, the symptoms, what causes it, how doctors test for it, and how it differs from the low cortisol lifestyle trend.
The short answer
Low cortisol, medically, is adrenal insufficiency: the body does not make enough cortisol. It is uncommon, serious and treatable. Common symptoms are long-lasting tiredness, weakness, weight loss, loss of appetite and low blood pressure; causes are medical, including autoimmune disease and stopping steroid medicine suddenly.
- Doctors diagnose it with blood tests such as the ACTH stimulation test, not from symptoms or quizzes.
- It is different from the low cortisol lifestyle trend, which is about everyday stress. Severe worsening symptoms can be adrenal crisis, an emergency.
Low cortisol, in the medical sense, means your body is not making enough of the hormone cortisol. The condition is called adrenal insufficiency (or hypocortisolism), and it is uncommon, serious and treatable. Feeling tired or stressed does not mean you have it, and it is not the same thing as the "low cortisol lifestyle" you may have seen online, which is about calming stress. This guide explains the real condition: what it is, the symptoms, the causes, how doctors test for it, and when it is an emergency.
General information, not medical advice. If you think you have low cortisol, see a doctor; do not start, stop or change any medicine on your own.
What does low cortisol mean?
Cortisol is made by the adrenal glands, two small glands above your kidneys. The NIDDK explains that cortisol helps your body handle stress and also helps regulate blood pressure, blood sugar, inflammation and metabolism. Low cortisol means the body is not making enough of it to meet its needs. The medical name is adrenal insufficiency, and the Cleveland Clinic also calls it hypocortisolism. Your cortisol follows a daily rhythm: it is typically highest in the morning, just before you wake, and lowest in the evening. A single reading says little without knowing the time it was taken, which is one reason this is a doctor's diagnosis, not a guess.
Low cortisol symptoms
The NIDDK lists the common symptoms below. The NHS stresses that many of them overlap with other conditions, so a GP or doctor should assess them. Early symptoms can come on slowly, which is why the condition is often missed at first.
| Type | What you might notice |
|---|---|
| Most common | Long-lasting tiredness, muscle weakness, loss of appetite, weight loss, abdominal pain |
| Also reported | Nausea, vomiting, diarrhea; low blood pressure that drops further when you stand, causing dizziness or fainting; irritability and low mood; joint pain; salt cravings; low blood sugar; irregular or absent periods; less interest in sex |
| Addison's disease only | Darkening of the skin, most visible on scars, skin folds, pressure points such as elbows and knees, the lips and inside the cheek |
| Adrenal crisis | A medical emergency; see below |
Sources: NIDDK and NHS. The NHS notes darker patches are harder to see on brown or black skin.
What causes low cortisol?
The NIDDK describes three types, depending on where the problem starts. All three are medical problems. Everyday stress is not on the list of causes.
| Type | Where the problem is | Common causes |
|---|---|---|
| Primary (Addison's disease) | The adrenal glands are damaged | Autoimmune disease causes about 8 or 9 in 10 cases in developed countries; others include tuberculosis, HIV/AIDS, adrenal cancer, surgery, bleeding into the glands, genetic conditions, and certain medicines |
| Secondary | The pituitary gland does not make enough ACTH, the signal that tells the adrenals to make cortisol | Autoimmune disease, pituitary tumors or infection, pituitary bleeding or surgery, genetic conditions, head injury |
| Tertiary | The hypothalamus does not make enough of the hormone that starts the chain | Most often suddenly stopping long-term corticosteroid medicine; also after surgery that cures Cushing's syndrome |
Source: NIDDK. Doctors taper corticosteroid doses over weeks or months, and the adrenal glands can take many months to recover.
This is why you should never stop a steroid medicine such as prednisone on your own. The NIDDK says suddenly stopping corticosteroids taken for a long time is the most common cause of low cortisol overall.
How common is low cortisol?
Rare. According to the NIDDK, Addison's disease affects about 100 to 140 people per million in developed countries, and secondary adrenal insufficiency about 150 to 280 per million. Women are more likely than men to develop Addison's disease, and it most often appears between ages 30 and 50, but it can occur at any age. These figures come from a page last reviewed in 2018.
Adrenal crisis: when low cortisol is an emergency
Adrenal crisis is the most serious complication, and it can be fatal if not treated immediately. The NIDDK says it is triggered by the body's higher need for cortisol during illness, injury or surgery, and that symptoms sometimes first appear during a crisis. The NHS says to call for emergency help (999 in the UK; 911 in the US) if symptoms suddenly get worse, especially with:
- a fast heart rate or severe dizziness,
- severe stomach or side pain, muscle weakness or spasms,
- a persistent headache or vomiting,
- drowsiness or confusion, a seizure, or loss of consciousness.
The NHS adds that people who have an emergency steroid injection should still call for help even after using it.
How is low cortisol diagnosed?
A doctor starts with your history and symptoms and then orders tests. The NIDDK diagnosis page describes:
- The ACTH stimulation test, the most commonly used one. You get an injection of synthetic ACTH and blood is drawn before and 30 or 60 minutes after. A normal response is a rise in cortisol; people with Addison's disease show little or none.
- The insulin tolerance test, used if that result is unclear or a pituitary problem is suspected. It must be supervised and is not safe for everyone.
- The CRH stimulation test, used to tell secondary from tertiary insufficiency.
- Tests for the cause, such as antibody blood tests, a CT scan of the adrenal glands, tuberculosis tests, or an MRI of the pituitary.
None of the medical sources above diagnose low cortisol from symptoms alone or from a quiz. If you are worried, the step is a doctor's appointment, not an online test or a supplement.
How is low cortisol treated?
The NHS says there is no cure, but it is managed with daily steroid medicine to replace the missing hormones, usually for life. The medicines it lists are hydrocortisone, prednisolone and fludrocortisone, with extra doses when you are unwell, having surgery or under unusual stress. People are advised to carry a steroid emergency card and an emergency injection kit. The NIDDK adds that with treatment, most people with adrenal insufficiency can lead normal, active lives.
Low cortisol vs the "low cortisol lifestyle"
The two are different things that share a name. The online trend is about lowering everyday stress: better sleep, calmer mornings, gentler workouts. It is not a medical condition, and wanting a calmer routine is reasonable. But "low cortisol" as a goal is a misleading phrase, because cortisol is essential to life and is supposed to rise every morning. A healthy pattern has a peak and a quiet evening, not as little cortisol as possible.
If your goal is the lifestyle one, our guide to how to lower cortisol covers what the research does and does not support, and the guide to falling asleep covers the habit most people struggle with first. If your concern is a rounder face, our guide to cortisol face explains the high-cortisol side.
Low cortisol vs high cortisol
They are opposite problems. Low cortisol (adrenal insufficiency) is too little of the hormone, with symptoms such as weight loss, low blood pressure and fatigue. High cortisol is too much, and it has its own medical causes and signs. Neither can be sorted out by feel, which is why testing matters.
When to see a doctor
- You have long-lasting tiredness with weight loss, loss of appetite, dizziness when you stand, salt cravings or darker patches of skin.
- You have taken steroid tablets for a long time and feel unwell after a dose is reduced or missed.
- You have symptoms that keep getting worse, even if you are not sure what is causing them.
- You have any of the emergency signs above: do not wait for an appointment.
Write down your symptoms, when they started, your medicines (including steroid creams, inhalers and tablets) and your questions before you go. The cause is what decides the treatment, so the more specific you can be, the faster a doctor can narrow it down.
Sources: NIDDK: adrenal insufficiency, symptoms and causes
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Questions people ask about this
What does low cortisol mean?
It means your body is not making enough cortisol, a hormone made by the adrenal glands. The medical name is adrenal insufficiency, or hypocortisolism. It is uncommon and treatable.
What are the symptoms of low cortisol?
Long-lasting tiredness, muscle weakness, loss of appetite, weight loss and abdominal pain are the most common. Others include low blood pressure that drops when you stand, salt cravings, low mood and, in Addison's disease, darker skin patches.
What causes low cortisol?
Damage to the adrenal glands (often autoimmune, called Addison's disease), a problem with the pituitary or hypothalamus that signals them, or suddenly stopping long-term steroid medicine. Everyday stress is not a listed cause.
Is low cortisol serious?
It can be. Untreated, it can lead to adrenal crisis, which can be fatal. With treatment, most people live normal, active lives.
Can stress cause low cortisol?
The causes listed by the NIDDK are medical: autoimmune disease, infections, pituitary problems, surgery and steroid withdrawal. Everyday stress is not on that list, though illness, injury or surgery raise your need for cortisol.
How do doctors test for low cortisol?
Most often with an ACTH stimulation test, where cortisol is measured in blood before and after an injection of synthetic ACTH. Other tests look for the cause, such as antibody tests, scans and tuberculosis tests.
What is the low cortisol lifestyle?
An online trend about lowering everyday stress through sleep, calmer routines and gentler exercise. It is not a medical condition and is not the same as having low cortisol.
When is cortisol highest?
Cortisol is typically highest in the morning, just before you wake, and lowest in the evening.
