Low Cortisol Symptoms: Drugs That Cause or Treat It

How Cortisol Production Works and Why Drugs Disrupt It

The hypothalamic-pituitary-adrenal (HPA) axis controls cortisol secretion through a tightly regulated feedback loop. The hypothalamus releases corticotropin-releasing hormone (CRH), the pituitary responds with adrenocorticotropic hormone (ACTH), and the adrenal cortex produces cortisol. Any drug that suppresses CRH, ACTH, or adrenal enzymatic activity can drive cortisol below the threshold your body needs to maintain blood pressure, glucose homeostasis, and immune function.

The Endocrine Society's 2016 clinical practice guideline defines adrenal insufficiency as inadequate cortisol production and recommends a morning serum cortisol <3 mcg/dL as highly suggestive of the diagnosis. Values between 3 and 15 mcg/dL require confirmatory testing with a 250 mcg cosyntropin stimulation test, where a peak cortisol <18 mcg/dL at 30 or 60 minutes confirms insufficiency [1]. Drug-induced suppression of the HPA axis accounts for the majority of secondary adrenal insufficiency cases encountered in clinical practice, far exceeding pituitary tumors or autoimmune adrenalitis as a cause [2].

Symptoms appear gradually in most drug-induced cases. Fatigue, orthostatic hypotension, nausea, weight loss, and hypoglycemia accumulate over weeks. The insidious onset means the diagnosis is frequently missed until a physiologic stressor (surgery, infection, trauma) unmasks a full adrenal crisis with hypotension and altered mental status.

Exogenous Glucocorticoids: The Most Common Culprit

Chronic exogenous glucocorticoid use suppresses ACTH secretion, leading to adrenal atrophy. This is the single most frequent drug cause of low cortisol after the medication is stopped. A systematic review published in the Journal of Clinical Endocrinology & Metabolism found that adrenal insufficiency occurred in 48.7% of patients after glucocorticoid withdrawal across all routes of administration, including oral, inhaled, topical, and intra-articular [3].

The risk scales with dose, duration, and potency. Prednisone at 5 mg per day or higher for more than three weeks is widely cited as the threshold above which HPA suppression becomes likely, though individual susceptibility varies. Even inhaled corticosteroids such as fluticasone at doses exceeding 500 mcg per day have triggered clinically significant adrenal suppression, particularly in children [4].

Recovery is slow. A prospective study in Annals of Internal Medicine demonstrated that HPA axis recovery after prolonged glucocorticoid therapy required a median of 12 months, with some patients still suppressed at 24 months [5]. The Endocrine Society recommends a gradual taper rather than abrupt cessation, reducing the dose by approximately 10% to 20% every one to two weeks once a physiologic-equivalent dose (prednisone 5 mg or hydrocortisone 20 mg daily) is reached [1].

Dr. Lynnette Nieman, Senior Investigator at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), has stated: "Patients who have received supraphysiologic glucocorticoids for more than a few weeks should be assumed to have HPA axis suppression until proven otherwise by biochemical testing" [6].

Opioid-Induced Adrenal Insufficiency

Opioids suppress cortisol production through direct inhibition of CRH and ACTH release. The condition is underrecognized. A meta-analysis in the Journal of Clinical Endocrinology & Metabolism pooled data from 21 studies and reported that opioid-induced adrenal insufficiency affected 15.4% of patients on chronic opioid therapy, with prevalence ranging from 9% to 29% depending on the population studied [7].

Morphine equivalents matter. Patients on daily doses exceeding 60 morphine milligram equivalents (MME) carry higher risk, though suppression has been documented at lower doses. Both short-acting and long-acting formulations contribute. Intrathecal opioid delivery carries a particularly high rate of HPA suppression, with one series reporting adrenal insufficiency in 15 of 47 patients (31.9%) receiving intrathecal morphine [8].

Symptoms overlap heavily with opioid side effects. Fatigue, nausea, and decreased appetite are attributed to the opioid itself, delaying recognition of adrenal insufficiency for months or years. The Endocrine Society recommends screening with a morning cortisol level in opioid-dependent patients who develop unexplained fatigue, hypotension, or hyponatremia, followed by ACTH stimulation testing if the cortisol value is equivocal [1].

Treatment involves hydrocortisone replacement if the opioid cannot be discontinued. When opioid tapering is feasible, repeat HPA axis testing three to six months after dose reduction can document recovery.

Immune Checkpoint Inhibitors and Hypophysitis

Checkpoint inhibitors (ipilimumab, nivolumab, pembrolizumab, and combination regimens) have introduced a new pattern of drug-induced hypocortisolism through autoimmune hypophysitis. The anterior pituitary becomes inflamed, ACTH-secreting cells are destroyed, and cortisol production collapses.

The incidence varies by regimen. Ipilimumab monotherapy causes hypophysitis in approximately 3.2% of patients. Combination ipilimumab plus nivolumab raises the rate to 6.4% to 17%, according to a pooled analysis published in JAMA Oncology examining 6,472 patients across 38 trials [9]. Anti-PD-1 monotherapy (nivolumab or pembrolizumab) carries a lower but non-negligible risk of 0.4% to 1.5%.

Onset typically occurs 6 to 12 weeks after treatment initiation. Headache, fatigue, and visual disturbances may precede biochemical evidence of cortisol deficiency. MRI often shows pituitary enlargement in the acute phase. The National Comprehensive Cancer Network (NCCN) guidelines on immune-related adverse events recommend holding the checkpoint inhibitor and starting high-dose glucocorticoids (prednisone 1 mg/kg) for grade 3 to 4 hypophysitis, with transition to physiologic hydrocortisone replacement once the acute phase resolves [10].

A key clinical distinction: ACTH deficiency from checkpoint inhibitor hypophysitis is usually permanent. Unlike glucocorticoid-withdrawal adrenal insufficiency, where recovery is expected, most patients with checkpoint-induced ACTH loss require lifelong hydrocortisone replacement. Dr. Patrizio Caturegli, Professor of Pathology at Johns Hopkins, noted in a 2018 review: "Corticotroph destruction from immune checkpoint inhibitor hypophysitis appears irreversible in the majority of cases, necessitating indefinite glucocorticoid replacement" [11].

Other Drugs That Suppress Cortisol

Several additional medications lower cortisol through distinct mechanisms.

Ketoconazole inhibits multiple adrenal steroidogenic enzymes, including 11-beta-hydroxylase and 17-alpha-hydroxylase. This property makes it useful for treating Cushing syndrome (FDA-approved as Nizoral for this indication at 400 to 1 to 200 mg daily), but the same mechanism can cause iatrogenic hypocortisolism if dosing is not monitored. The European Medicines Agency's assessment documented that 10% to 15% of ketoconazole-treated patients with Cushing syndrome required temporary hydrocortisone supplementation due to cortisol oversuppression [12].

Etomidate, an intravenous anesthetic, blocks 11-beta-hydroxylase even in single induction doses. A Cochrane systematic review confirmed that a single intubating dose of etomidate (0.3 mg/kg) suppresses cortisol for 12 to 24 hours, though the clinical significance in non-critically-ill patients remains debated [13]. In critically ill or septic patients, the 2017 Society of Critical Care Medicine guidelines recommend against etomidate given its adrenal suppressive effects [14].

Metyrapone and mitotane are additional adrenal enzyme inhibitors used in Cushing syndrome management. Mitotane is directly adrenolytic and causes permanent adrenal insufficiency in most patients, requiring concomitant hydrocortisone and fludrocortisone replacement throughout treatment.

Megestrol acetate, a synthetic progestational agent used as an appetite stimulant, has intrinsic glucocorticoid activity. When discontinued abruptly, patients can develop symptomatic adrenal insufficiency because the exogenous glucocorticoid effect suppressed endogenous ACTH during use [15].

How Low Cortisol Is Diagnosed

Diagnosis follows a stepwise biochemical approach. The morning serum cortisol drawn between 8:00 and 9:00 AM is the initial screening test. A value below 3 mcg/dL confirms insufficiency in the right clinical context. Values above 15 mcg/dL make the diagnosis unlikely.

The standard-dose (250 mcg) cosyntropin stimulation test resolves indeterminate cases. Synthetic ACTH is injected intravenously or intramuscularly, and serum cortisol is measured at baseline, 30 minutes, and 60 minutes. A peak below 18 mcg/dL confirms adrenal insufficiency [1]. The American Association of Clinical Endocrinology (AACE) recommends pairing the stimulation test with a simultaneous ACTH level to distinguish primary (ACTH elevated) from secondary (ACTH low or inappropriately normal) adrenal insufficiency [16].

For suspected drug-induced cases, the clinical timeline is often diagnostic on its own. Onset of fatigue, hypotension, and hyponatremia within weeks of starting or stopping a known offending drug, combined with a low morning cortisol, should trigger confirmatory testing and immediate treatment without waiting for stimulation test results if the patient is hemodynamically unstable.

Additional laboratory findings that support the diagnosis include hyponatremia (present in 80% of adrenal crisis episodes), hypoglycemia, mild eosinophilia, and, in primary adrenal insufficiency, hyperkalemia. Renin and aldosterone levels help confirm primary versus secondary disease.

Treatment: Hydrocortisone Replacement and Stress Dosing

Physiologic cortisol replacement with oral hydrocortisone is the standard treatment. The Endocrine Society guideline recommends 15 to 25 mg daily in two or three divided doses, with the largest dose given upon waking to mimic the diurnal cortisol rhythm [1]. A typical regimen is 10 mg on waking, 5 mg at noon, and 5 mg in the late afternoon. Some clinicians prefer modified-release hydrocortisone (Plenadren), which provides a more physiologic cortisol profile with once-daily dosing.

Prednisolone (3 to 5 mg daily) or dexamethasone (0.25 to 0.5 mg daily) are alternatives when hydrocortisone is unavailable or adherence to multiple daily doses is poor. Dexamethasone lacks mineralocorticoid activity entirely, and prednisolone has minimal mineralocorticoid effect, so neither substitutes for fludrocortisone in primary adrenal insufficiency.

Fludrocortisone at 0.05 to 0.2 mg daily is added only in primary adrenal insufficiency, where aldosterone production is also impaired. Secondary adrenal insufficiency (the category encompassing most drug-induced cases) preserves the renin-angiotensin-aldosterone axis, so mineralocorticoid replacement is unnecessary [1].

Stress dosing prevents adrenal crisis during physiologic stress. The Endocrine Society recommends doubling or tripling the oral hydrocortisone dose during febrile illness (temperature above 38°C). For major surgery, the guideline specifies hydrocortisone 100 mg IV bolus followed by 50 mg every 8 hours, tapered over one to three days as the patient recovers [1]. Every patient on chronic glucocorticoid replacement should carry a medical alert identification and an emergency injection kit containing 100 mg hydrocortisone for intramuscular self-administration.

A retrospective cohort study in the Journal of Clinical Endocrinology & Metabolism found that among 423 patients with adrenal insufficiency followed over 10 years, adrenal crisis occurred at a rate of 6.3 episodes per 100 patient-years, with gastrointestinal illness and infection as the most common precipitants [17]. Mortality from adrenal crisis remains 0.5 per 100 patient-years in well-managed populations, underscoring that replacement therapy must be paired with patient education on sick-day rules.

When to Worry: Red Flags for Adrenal Crisis

Not all low cortisol presents gently. Adrenal crisis is a medical emergency defined by acute hemodynamic collapse (systolic blood pressure <100 mmHg) in the setting of cortisol deficiency. It carries a case-fatality rate of approximately 6% even with treatment [17].

Seek emergency care immediately if you or a patient on known adrenal-suppressive therapy develops sudden severe hypotension, altered consciousness, unexplained abdominal pain with vomiting, or fever unresponsive to antipyretics. Empiric hydrocortisone 100 mg IV should be administered before waiting for confirmatory labs. A normal saline bolus of 1 to 2 liters addresses the concurrent volume depletion.

Patients transitioning off chronic glucocorticoids, those recently started on checkpoint inhibitors (especially combination regimens), and chronic opioid users who abruptly reduce their dose represent the highest-risk groups for precipitous cortisol decline. Proactive HPA axis screening in these populations, rather than waiting for symptoms, is the approach most likely to prevent crisis events.

The minimum monitoring interval for patients tapering off chronic glucocorticoids: repeat morning cortisol every four to six weeks once the dose reaches physiologic range (prednisone 5 mg or equivalent), continuing until a value above 10 mcg/dL or a normal cosyntropin stimulation test confirms HPA recovery [1].