The condition is usually the result of a problem with the immune system, which causes it to attack the outer layer of the adrenal gland (the adrenal cortex), disrupting the production of the steroid hormones aldosterone and cortisol. It's not clear why this happens, but it's responsible for 70% to 90% of cases in the UK.
Other potential causes include conditions that can damage the adrenal glands, such as tuberculosis (TB), although this is uncommon in the UK.
Read more about the causes of Addison's disease.
Addison's disease is treated with medication to replace the missing hormones. You'll need to take the medication for the rest of your life.
With treatment, symptoms of Addison's disease can largely be controlled. Most people with the condition have a normal lifespan and are able to live an active life with few limitations.
People with Addison's disease must be constantly aware of the risk of a sudden worsening of symptoms, called an adrenal crisis. This can happen when the levels of cortisol in your body fall significantly.
An adrenal crisis is a medical emergency. If left untreated, it can be fatal. If you or someone you know has Addison's disease and is experiencing severe symptoms, dial 999 for an ambulance.
Read more about treating Addison's disease.
If you have Addison's disease, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.