Addison’s disease is a rare condition in which the adrenal glands, two small glands sitting on top of your kidneys, stop producing enough of the hormones your body needs to regulate blood pressure, metabolism, and stress responses. It affects roughly 82 to 221 people per million depending on geographic region, with higher rates in Northern Europe. The average age at diagnosis falls between the late 30s and early 40s for both men and women.
What the Adrenal Glands Normally Do
Your adrenal glands produce two critical hormones. The first, cortisol, helps your body convert food into energy, manage blood sugar, respond to stress, and control inflammation. The second, aldosterone, tells your kidneys how much sodium to hold onto and how much potassium to release. Together, these hormones keep your blood pressure stable, your electrolytes balanced, and your energy levels functional throughout the day.
In Addison’s disease, the outer layer of the adrenal glands is gradually destroyed, and cortisol production drops first. Aldosterone follows. As both hormones decline, the brain’s pituitary gland tries to compensate by pumping out higher and higher levels of a stimulating hormone called ACTH, essentially shouting at the adrenal glands to work harder. That rising ACTH level is responsible for one of the disease’s most distinctive signs: darkening skin.
Why It Happens
In 70 to 90% of cases, Addison’s disease is caused by the body’s own immune system attacking the adrenal glands. This autoimmune destruction happens slowly, often over months or years, and symptoms don’t typically appear until about 90% of the adrenal cortex has been damaged. People with one autoimmune condition, such as type 1 diabetes or thyroid disease, face a higher risk of developing another, including Addison’s.
Tuberculosis accounts for 7 to 20% of cases and was historically the leading cause before antibiotics became widely available. Less commonly, fungal infections, cancer that has spread to the adrenal glands, bleeding into the glands, or certain genetic conditions can trigger the disease.
Recognizing the Symptoms
Because the hormone decline is gradual, early symptoms are easy to dismiss. Extreme fatigue, decreased appetite, unintentional weight loss, and nausea are often the first signs. Many people also experience low blood pressure that causes dizziness when standing up quickly, along with muscle cramps and an unusual craving for salty foods (your body’s way of signaling that it’s losing too much sodium).
The most characteristic physical sign is hyperpigmentation, patches of unusually dark skin that show up in areas exposed to friction like the knuckles, elbows, armpits, and creases of the palms. The lips and inside of the mouth can darken too. This happens because the excess ACTH the pituitary releases shares a chemical pathway with a hormone that stimulates pigment-producing cells in the skin. The more ACTH circulates, the darker certain areas become.
Women may notice a loss of underarm and pubic hair due to shifts in adrenal hormones involved in sexual characteristics. Blood work often reveals low sodium (below 135 mEq/L), elevated potassium (above 5 mEq/L), and low blood sugar. Some people develop mild anemia or changes in white blood cell counts.
How Addison’s Disease Is Diagnosed
The key diagnostic test is the ACTH stimulation test. A healthcare provider injects a synthetic version of ACTH into your bloodstream, then measures your cortisol levels 30 to 60 minutes later. In a healthy person, cortisol rises sharply in response. In someone with Addison’s disease, cortisol barely moves because the damaged adrenal glands can’t respond to the signal.
If the stimulation test confirms adrenal insufficiency, a follow-up test called the CRH stimulation test can help pinpoint the cause. CRH is the hormone that normally tells the pituitary to release ACTH. Blood samples are drawn before and at 30, 60, 90, and 120 minutes after a CRH injection. If ACTH rises normally but cortisol doesn’t, the problem is in the adrenal glands themselves, confirming primary adrenal insufficiency. If ACTH fails to rise, the issue lies in the pituitary gland instead.
Blood tests checking sodium, potassium, and blood sugar levels provide supporting evidence. Antibody tests can confirm autoimmune adrenalitis, and imaging of the adrenal glands can reveal shrinkage, calcification from tuberculosis, or other structural damage.
Daily Hormone Replacement
Addison’s disease is a lifelong condition, but it’s manageable with daily hormone replacement. The standard approach replaces cortisol with oral hydrocortisone, typically 15 to 25 mg per day split into two or three doses that mimic the body’s natural rhythm of higher cortisol in the morning and lower levels at night. Some people take an alternative steroid at equivalent doses.
Since the adrenal glands also stop making aldosterone, most people with Addison’s disease take a separate medication to replace that hormone and keep sodium, potassium, and blood pressure in balance. Periodic check-ins monitor weight, blood pressure, electrolyte levels, and general well-being to make sure the doses stay appropriate.
One important consideration with long-term treatment is bone health. Studies have found that the replacement doses commonly used for Addison’s disease, which tend to slightly exceed what the body would naturally produce, can reduce bone mineral density in the spine and hips over time. Research suggests that lowering doses when clinically appropriate can improve bone density without increasing the risk of adrenal crisis, which is why keeping replacement doses as low as effectively possible matters.
Stress Dosing and Sick Day Rules
A healthy body naturally ramps up cortisol production during illness, injury, or physical stress. When your adrenal glands can’t do that, you need to manually increase your medication. These adjustments follow what doctors call “sick day rules,” and learning them is one of the most important parts of managing Addison’s disease.
Rule one covers moderate illness: if you develop a fever, an infection requiring antibiotics, or any illness that keeps you in bed, you double your normal oral dose. The same applies before minor procedures like dental work. You should keep at least a week’s extra supply of medication on hand at all times. Rule two covers more serious situations: if you’re vomiting and can’t keep pills down, facing surgery, experiencing severe trauma, or fasting for a medical procedure, you need an injectable form of the medication because oral tablets won’t be absorbed reliably.
Educating family members and close contacts on these rules is just as important as knowing them yourself, since an adrenal crisis can impair your ability to manage your own care.
Adrenal Crisis: The Emergency to Prepare For
An adrenal crisis is the most dangerous complication of Addison’s disease. It occurs when cortisol levels drop so low that the body can no longer maintain basic functions. It can be triggered by an infection, a missed dose of medication, surgery, or severe physical stress, and it progresses quickly.
Early warning signs include sudden worsening of fatigue, nausea, vomiting, abdominal or back pain, dizziness, and confusion. Without treatment, blood pressure drops to dangerous levels (systolic below 100 mmHg or at least 20 mmHg below your usual baseline), and the situation can escalate to shock, loss of consciousness, and coma. With prompt treatment, including intravenous fluids and injectable hydrocortisone, most people see significant improvement within one to two hours, with blood pressure beginning to stabilize in the first hour.
People with Addison’s disease are generally advised to wear a medical alert bracelet and carry an emergency injection kit. Because the early symptoms of a crisis overlap with many common illnesses, having that identification can make the difference between rapid, appropriate treatment and a dangerous delay.