Addison's disease can be difficult to detect at first because early symptoms are similar to those of many other health conditions.

Initial symptoms of Addison's disease can include:

• lack of energy or motivation (fatigue)
• abnormal drowsiness or tiredness (lethargy)
• muscle weakness
• low mood (mild depression) or irritability
• loss of appetite and unintentional weight loss
• the need to urinate frequently
• increased thirst
• craving salty foods

Dehydration can also be an early sign of Addison's disease. It's caused by lack of the hormone aldosterone in your body, which is used to regulate the balance of salt and water.

Later symptoms

Further symptoms of Addison's disease tend to develop gradually over months or years. However, additional stress, caused by another illness or an accident, for example, may cause your symptoms to suddenly get worse.

You may go on to develop:

• low blood pressure when you stand up, which can cause dizziness and fainting 
• nausea (feeling sick)
• vomiting (being sick)
• diarrhoea
• abdominal, joint or back pain
• muscle cramps 
• chronic exhaustion, which may cause depression
• brownish discolouration of the skin, lips and gums (hyperpigmentation), particularly in the creases on your palms, on scars or on pressure points, such as your knuckles or knees
• a lack of interest in sex (reduced libido), particularly in women

Some women may also have irregular periods or miss some periods completely. Children with Addison's disease may go through puberty later than usual.

Some people with Addison's disease also develop low blood sugar (hypoglycaemia). This can cause symptoms such as difficulty concentrating, confusion, anxiety and even unconsciousness (particularly in children).

If you're experiencing symptoms of Addison's disease, see your GP so they can diagnose or rule out the condition. These symptoms will usually improve with appropriate treatment.

Read more about diagnosing Addison's disease and treating Addison's disease.

Adrenal crisis

If Addison's disease is left untreated, the levels of hormones produced by the adrenal gland gradually decrease in the body. This causes your symptoms to get progressively worse and eventually leads to a life-threatening situation called an adrenal or Addisonian crisis.

During an adrenal crisis, the symptoms of Addison's disease appear quickly and severely. This could happen when you're already experiencing initial symptoms or without any symptoms at all.

Signs of an adrenal crisis include:

• severe dehydration
• pale, cold, clammy skin
• sweating
• rapid, shallow breathing
• dizziness
• severe vomiting and diarrhoea
• severe muscle weakness
• headache
• severe drowsiness or loss of consciousness

An adrenal crisis is a medical emergency. If left untreated, it can be fatal. If you think you or someone you know with Addison's disease is having an adrenal crisis, dial 999 for an ambulance.

If an adrenal crisis is not treated, it can lead to a coma and death. There's also a risk your brain will not get enough oxygen if treatment is delayed, which can cause permanent disability.

Addison's disease develops when the outer layer of your adrenal glands (adrenal cortex) is damaged, reducing the levels of hormones it produces.

Problems with the immune system

A problem with the immune system is the most common cause of Addison's disease in the UK, accounting for 70% to 90% of cases.

The immune system is your body's defence against infection and disease. If you're ill, your immune system produces antibodies – a special type of protein that destroys disease-carrying organisms and toxins. These antibodies attack the cause of the illness.

However, if you develop a problem with your immune system, it can start to attack your own healthy tissues and organs. This is called an autoimmune disorder.

Addison's disease can develop if your immune system attacks your adrenal glands and severely damages your adrenal cortex.

When 90% of the adrenal cortex is destroyed, your adrenal glands will not be able to produce enough of the steroid hormones cortisol and aldosterone. Once levels of these start decreasing, you'll experience symptoms of Addison's disease.

It's not clear why some people develop this problem with their immune system, although it can run in families.

Genetics

Research has shown that some people with certain genes are more likely to develop autoimmune disorders.

It's not clear how these genes lead to Addison's disease and similar conditions, but it does mean your risk of developing Addison's disease is increased if you or a close family member have another autoimmune condition, such as:

• vitiligo – a long-term condition that causes pale, white patches to develop on the skin
• type 1 diabetes – a long-term condition caused by your body not producing insulin
• underactive thyroid gland (hypothyroidism)

Other causes

Tuberculosis (TB) is the most common cause of Addison's disease worldwide, but it's rare in the UK.

TB is a bacterial infection that mostly affects the lungs but can also spread to other parts of your body. It can cause Addison's disease if it damages your adrenal glands.

Other possible causes of Addison's disease include:

• infections – such as those linked to AIDS, or fungal infections
• a haemorrhage – very heavy bleeding into the adrenal glands, sometimes associated with meningitis or other types of severe sepsis
• cancer – if cancer cells from elsewhere in your body spread to your adrenal glands
• amyloidosis – a disease where amyloid, a protein produced by your bone marrow cells, builds up in and damages your adrenal glands
• surgical removal of both adrenal glands (adrenalectomy) – for example, to remove a tumour
• adrenoleukodystrophy (ALD) – a rare, life-limiting inherited condition that affects the adrenal glands and nerve cells in the brain, and is mostly seen in young boys
• certain treatments needed for Cushing's syndrome – a collection of symptoms caused by very high levels of cortisol in the body

Secondary adrenal insufficiency

The production of hormones from the adrenal gland can also be affected by damage to the pituitary gland – a pea-sized gland located below the brain that produces a hormone that stimulates the adrenal gland. This is called secondary adrenal insufficiency and is a separate condition to Addison's disease.

Secondary adrenal insufficiency can occur if your pituitary gland becomes damaged – for example, because of a tumour on the pituitary gland (pituitary adenoma).

To help diagnose Addison’s disease, your GP will first ask about your symptoms and review your medical history.

They're also likely to ask if anyone in your family has an autoimmune disorder (a condition caused by a problem with their immune system).

Your GP will examine your skin for any evidence of brownish discolouration (hyperpigmentation), particularly in certain areas, such as:

• the creases on your palm
• your elbow crease
• on any scars
• your lips and gums

However, hyperpigmentation does not occur in all cases of Addison's disease.

You'll also be tested for low blood pressure (hypotension) while you're lying down and again shortly after you stand up. This is to see whether you have low blood pressure when you change position (postural or orthostatic hypotension).

Blood tests

If Addison's disease is suspected, blood tests will be carried out to measure the levels of sodium, potassium and cortisol in your body. A low sodium, high potassium or low cortisol level may indicate Addison's disease.

You may need to see a hospital hormone specialist (endocrinologist) for your blood to be tested for the following:

• a low level of the hormone aldosterone
• a high level of adrenocorticotrophic hormone (ACTH)
• a low level of glucose (sugar used for energy)
• positive adrenal antibodies (antibodies designed to attack the adrenal gland)

Any of the above could be a sign of Addison's disease.

Synacthen stimulation test

If cortisol in your blood is low or your symptoms strongly suggest Addison's disease, you'll need to have a synacthen stimulation test to confirm the diagnosis.

Your GP may refer you to an endocrinology unit (a unit that specialises in the study of hormones) for the test. How urgent the referral is will depend on how severe your symptoms are.

Synacthen is a man-made (synthetic) copy of the adrenocorticotrophic hormone (ACTH). ACTH is naturally produced by the pituitary gland (a pea-sized gland below the brain) to encourage the adrenal glands to release cortisol and aldosterone.

When synacthen is given, the adrenal glands should respond in the same way as they would to ACTH by releasing cortisol and other steroid hormones into the blood.

A blood sample will be taken and tested for cortisol before an injection of synacthen is given into your arm. Further blood samples will be taken to measure cortisol after 30 minutes and after 60 minutes.

If the ACTH level is high but the cortisol and aldosterone levels are low, it's usually confirmation of Addison's disease.

Thyroid function test

Your thyroid gland may also be tested to see if it's working properly.

Your thyroid gland is found in your neck. It produces hormones that control your body's growth and metabolism.

People with Addison's disease often have an underactive thyroid gland (hypothyroidism), where the thyroid gland does not produce enough hormones.

By testing the levels of certain hormones in your blood, your endocrinologist (a specialist in hormone conditions) can determine whether you have hypothyroidism.

Scans

In some cases, your specialist may refer you for a scan of your adrenal glands – this could be a CT scan or an MRI scan.

Diagnosis during an adrenal crisis

If Addison's disease is left untreated, it eventually leads to an adrenal crisis. This is where the symptoms of Addison's disease appear quickly and severely.

During an adrenal crisis, there's not enough time to perform a synacthen stimulation test to confirm Addison's disease.

If possible, blood will be taken and tested for any of the abnormalities listed above. While you're waiting for the results, treatment may be started with steroid injections, and fluids containing salt and glucose.

Read more about treating Addison's disease.

Driving

If you're diagnosed with Addison's disease and have a bus, coach or lorry licence, it's your legal obligation to inform the Driver and Vehicle Licensing Agency (DVLA).

Read about driving and Addison's disease on the GOV.UK website.

If you have Addison's disease, you'll need to take daily medication to replace the lost hormones. This should help you to live an active life, although many people find they still need to manage their fatigue.

In some cases, the underlying causes of Addison's disease can be treated. For example, tuberculosis (TB) is treated with a course of antibiotics over a period of at least 6 months.

However, most cases are caused by a problem with the immune system that cannot be cured.

Medication for Addison's disease

Treatment usually involves corticosteroid (steroid) replacement therapy for life. Corticosteroid medication is used to replace the hormones cortisol and aldosterone that your body no longer produces. It's usually taken in tablet form 2 or 3 times a day.

In most cases, a medication called hydrocortisone is used to replace the cortisol. Other possible medicines are prednisolone or dexamethasone, although these are less commonly used. 

Aldosterone is replaced with a medication called fludrocortisone. Your GP may also ask you to add extra salt to your daily diet, although if you're taking enough fludrocortisone medicine this may not be necessary. Unlike most people, if you feel the urge to eat something salty, then you should eat it.

In general, the medications used for Addison's disease don't have side effects, unless your dose is too high. If you take a higher dose than necessary for a long time, there's a risk of problems such as weakened bones (osteoporosis), mood swings and difficulty sleeping (insomnia).

Living with Addison's disease

Many people with Addison's disease find that taking their medication enables them to continue with their normal diet and exercise routines.

However, bouts of fatigue are also common, and it can take some time to learn how to manage these periods of low energy.

Some people find that needing to take regular doses of medication is restrictive and affects their daily life or emotional health. Missing a dose of medication, or taking it late, can also lead to exhaustion or insomnia.

Some people can develop associated health conditions, such as diabetes or an underactive thyroid, which require extra treatment and management.

You'll usually need to have appointments with an endocrinologist every 6 to 12 months so they can review your progress and adjust your medication dose, if necessary. Your GP can provide support and repeat prescriptions in between these visits.

Failing to take your medication could lead to a serious condition called an adrenal crisis, so you must:

• remember to collect your repeat prescriptions
• keep spare medication as necessary – for example, in the car or at work, and always carry some spare medication with you
• take your medication every day at the right time
• pack extra medication if you're going away – usually double what you would normally need, plus your injection kit (see below)
• carry your medication in your hand luggage if you are travelling by plane, with a note from your doctor explaining why it is necessary

You could also inform close friends or colleagues of your condition. Tell them about the signs of adrenal crisis and what they should do if you experience one.

Medical alert bracelets

It's also a good idea to wear a medical alert bracelet or necklace that informs people you have Addison's disease.

After a serious accident, such as a car crash, a healthy person produces more cortisol. This helps you cope with the stressful situation and additional strain on your body that results from serious injury. As your body cannot produce cortisol, you'll need a hydrocortisone injection to replace it and prevent an adrenal crisis.

Wearing a medical alert bracelet will inform any medical staff treating you about your condition and what medication you require.

Medical alert bracelets or necklaces are pieces of jewellery engraved with your medical condition and an emergency contact number. They are available from a number of retailers. Ask your GP if there's one they recommend, or go to the MedicAlert website. 

If you need to stay in hospital, the healthcare professionals responsible for your care will also need to know you need steroid replacement medication throughout your stay. It's important to note that this advice still applies even if you're not supposed to eat or drink (nil by mouth) for any reason.

Adjusting your medication

At certain times, your medication may need to be adjusted to account for any additional strain on your body. For example, you may need to increase the dosage of your medication if you experience any of the following:

• an illness or infection – particularly if you have a high temperature of 38C or above
• an accident, such as a car crash
• an operation, dental or medical procedure – such as a tooth filling or endoscopy
• strenuous exercise that's not usually part of your daily life

This will help your body cope with the additional stress. Your endocrinologist will monitor your dosage and advise about any changes.

Over time, as you get used to the condition and learn what can trigger your symptoms, you may learn how to adjust your medication yourself. However, always consult your GP or specialist if you're unsure.

Emergency treatment

You and a partner or family member may be trained to administer an injection of hydrocortisone in an emergency.

This could be necessary if you go into shock after an injury, or if you experience vomiting or diarrhoea and are unable to keep down oral medication. This may occur if you're pregnant and have morning sickness. Your endocrinologist will discuss with you when an injection might be necessary.

If you need to administer emergency hydrocortisone, always call your GP immediately afterwards. Check what out-of-hours services are available in your local area, in case the emergency is outside normal working hours.

You can also register yourself with your local ambulance service, so they have a record of your requirement for a steroid injection or tablets, if you need their assistance.

Treating adrenal crisis

Adrenal crisis, or Addisonian crisis, needs urgent medical attention. Dial 999 for an ambulance if you or someone you know are experiencing adrenal crisis.

Signs of an adrenal crisis include:

• severe dehydration
• pale, cold, clammy skin
• sweating
• rapid, shallow breathing
• dizziness
• severe vomiting and diarrhoea
• severe muscle weakness
• headache
• severe drowsiness or loss of consciousness

In hospital, you'll be given lots of fluid through a vein in your arm to rehydrate you. This will contain a mixture of salts and sugars (sodium, glucose and dextrose) to replace what your body is lacking. You'll also be injected with hydrocortisone to replace the missing cortisol hormone.

Any underlying causes of the adrenal crisis, such as an infection, will also be treated.

Free prescriptions

If you're receiving treatment for Addison's disease, you're entitled to a medical exemption certificate. This means you don't have to pay for any prescriptions you need.

See help with prescription costs for more information.