Is cosyntropin FDA-approved, and what does the research show?

What is cosyntropin?

Cosyntropin is a diagnostic test agent for the adrenal glands ¹, not a wellness, weight or performance peptide. It is a synthetic peptide made of the first 24 of the 39 amino acids of ACTH, in the same order ¹. The pituitary sits at the base of the brain. Its ACTH makes the adrenal glands release cortisol ².

The label calls cosyntropin "synthetic beta 1 - 24 corticotropin, a synthetic subunit of ACTH" ¹. Its international name is tetracosactide, and FDA's substance registry also lists tetracosactrin and "ADRENOCORTICOTROPIC HORMONE FRAGMENT 1-24 HUMAN, RAT" as names for it ⁶. Amphastar Pharmaceuticals holds the approval for Cortrosyn, and Sandoz holds an approved generic ³. It is not the same as Acthar Gel, repository corticotropin, "a naturally sourced complex mixture of adrenocorticotropic hormone analogs and other pituitary peptides" from pig pituitary, approved as a treatment for several conditions ¹, ².

Is cosyntropin FDA-approved?

Yes. Cosyntropin is approved by FDA as the prescription product Cortrosyn, "indicated, in combination with other diagnostic tests, for use as a diagnostic agent in the screening of adrenocortical insufficiency in adults and pediatric patients" ¹. The label's "adrenocortical insufficiency" ¹ is the condition the research papers call adrenal insufficiency ⁵, ⁴. That is the label's only indication ¹.

Drugs@FDA, FDA's public register of approved drugs, shows Amphastar's new drug application (NDA) 016750 approved on April 22, 1970, with marketing status "Prescription" ³. One generic, Sandoz's abbreviated new drug application (ANDA) 202147, the form a generic takes, was approved June 29, 2012 and carries the same status ³. Two further applications, a Sandoz solution form approved in 2008 and a second generic approved in 2009, are listed as discontinued ³. The 2023 label's own header reads "Initial U.S. Approval: 2008" ¹.

FDA approved the current label on December 22, 2023 ³. A clinician orders it by prescription ³.

See the FDA status of every peptide, updated weekly.

How does cosyntropin work?

Cosyntropin "exhibits the full corticosteroidogenic activity of natural ACTH," the label says, meaning it drives the adrenal cortex to make its steroid hormones as the natural hormone does ¹. The adrenal cortex is the outer layer of the gland, which ACTH stimulates "to secrete cortisol, corticosterone, aldosterone," two related steroid hormones, "and a number of weakly androgenic substances," weak male-type hormones ². The label says studies place ACTH's biological activity in its first 20 amino acids ¹. Shortening the chain below 20 amino acids loses part or all of the activity ¹. The label states that the adult dose stimulates the adrenal cortex "maximally," as natural ACTH does ¹.

The 1-24 fragment has a second property the label names. The label places the greatest antigenicity, the power to provoke an immune response, in amino acids 22 to 39 ¹. Peptides of 1-24, it says, "have very little immunologic although full biologic activity" ¹. The label says this matters "in view of the known antigenicity of natural ACTH" ¹.

The test rests on that response. The label times blood draws at 30 and 60 minutes ¹. A gland that cannot respond gives a low reading ¹.

What does the research show?

What the test measures. A cortisol level after the injection that falls below the label's cutoff is "suggestive of adrenocortical insufficiency," and the label adds that cutoffs "may vary according to the assay used" ¹. Two kinds of adrenal insufficiency are tested: the papers call them secondary ⁴, or hypothalamic-pituitary ⁵, and primary ⁷. Secondary adrenal insufficiency is a shortage of ACTH from the pituitary or the hypothalamus above it, which leaves the glands understimulated. Primary adrenal insufficiency is disease of the adrenal glands themselves.

Studied in people: a 2008 meta-analysis, a study that combines the results of separate studies. This one, published online August 12, 2008, used each patient's own record rather than each study's summary ⁵. It pooled 679 people from 13 of 23 eligible studies, all tested because chronic secondary adrenal insufficiency was suspected ⁵. The benchmark was the insulin hypoglycemia or metyrapone test, two other tests of the same system that are accepted as the reference standard ⁵. Studies of intensive-care patients or of healthy controls alone were excluded ⁵.

It compared the standard-dose test, which the 2015 review below calls high-dose ⁴, ¹, with a low-dose version ⁵. Accuracy was measured as the area under the ROC curve ⁵, a summary score of a test's accuracy on which 1.0 is a perfect test and 0.5 is a coin toss. The low-dose test scored 0.92, with a 95 percent confidence interval, the range the true value most likely lies in, of 0.89 to 0.94 ⁵.

The standard-dose test scored 0.79, with an interval of 0.74 to 0.84 ⁵. In the 254 people from seven studies who had both tests, the scores were 0.94 and 0.85 ⁵. The authors concluded that the low-dose test "was superior to standard-dose test for diagnosing chronic HPAI, although it has technical limitations," HPAI being the secondary kind of adrenal insufficiency ⁵.

Studied in people: a 2015 systematic review, a review that searches for every study by a set method. This larger review, published online December 9, 2015, searched six databases through February 2014 ⁴. It pooled 30 studies of secondary adrenal insufficiency, enrolling 1,209 adults and 228 children ⁴. The high-dose and low-dose tests "had similar diagnostic accuracy in adults and children using different peak serum cortisol cutoffs" ⁴.

Both had low sensitivity, the share of true cases a test catches, and high specificity, the share of people without the condition it clears: "Both tests are adequate to rule in, but not rule out, secondary adrenal insufficiency" ⁴. A likelihood ratio says how much a result shifts the odds of the condition, up when it is above 1 and down when it is below. In adults, the likelihood ratio for a positive high-dose test was 9.1 and for a negative one 0.39; in children, 43.5 and 0.65 ⁴. For primary adrenal insufficiency, five studies of 100 patients allowed only an estimate of the high-dose test's sensitivity, 92 percent, with a 95 percent confidence interval of 81 to 97 ⁴. The authors rated their confidence in these estimates "low to moderate because of the likely risk of bias, heterogeneity, and imprecision," heterogeneity meaning the studies differed from one another ⁴.

The guideline. The Endocrine Society, the professional body of hormone specialists, published a guideline on primary adrenal insufficiency online on January 13, 2016 ⁷. It recommends the standard-dose test, which it calls the short corticotropin test, as the "gold standard" diagnostic tool ⁷. Where that test cannot be done first, it recommends measuring morning plasma ACTH and cortisol as a screen ⁷. Its task force "received no corporate funding" ⁷.

Not studied as a treatment. ClinicalTrials.gov, the U.S. registry of clinical trials, held 42 studies with cosyntropin as an intervention on November 10, 2026. At least four of them tested it as a treatment, and the label lists no such use ⁸, ⁹, ¹⁰, ¹¹, ¹. Two were for headache after a spinal puncture ⁸, ⁹, one for membranous nephropathy, a kidney disease ¹⁰, and one for infantile spasms, a seizure disorder of infancy ¹¹. None of the 42 registered studies cited here tests it for weight loss, energy or aging ¹²; one tested a cosyntropin product in Duchenne muscular dystrophy ¹³, a muscle-wasting disease.

What are the side effects?

The label lists reactions reported since approval, from "a population of uncertain size," so their frequency cannot be reliably estimated: "anaphylactic reaction, bradycardia, tachycardia, hypertension, peripheral edema, and rash" ¹. Anaphylaxis is a severe, whole-body allergic reaction, and bradycardia and tachycardia are a slow and a fast heartbeat. Hypertension is high blood pressure, and peripheral edema is swelling of the legs or hands from fluid.

The label's contraindication, the case in which it must not be given, is "a history of hypersensitivity," an allergic reaction, "to cosyntropin or to any excipients," the inactive ingredients, "of CORTROSYN," and it says "Reactions have included anaphylaxis" ¹. The label's first warning is to monitor for hypersensitivity reactions and treat them ¹. It asks clinicians to tell patients the early signs: rash, hives, itching, facial swelling, tightness of the chest and wheezing ¹.

The label's second warning concerns the test's accuracy. Glucocorticoids, the cortisol-like steroid medicines, and spironolactone, a diuretic, "may result in falsely elevated cortisol levels" ¹. Estrogen-containing drugs raise cortisol binding globulin, the blood protein that carries cortisol, which raises the measured total cortisol ¹. Cirrhosis, scarring of the liver, and nephrotic syndrome, a kidney condition, can lower cortisol binding globulin and so lower the measured cortisol ¹.

Pregnancy and children. The label says case reports "over decades of use" in pregnancy "have not identified an increased risk of major birth defects, miscarriage or adverse maternal or fetal outcomes" ¹. It warns that unidentified adrenal insufficiency in pregnancy "can result in maternal and/or fetal death," so the diagnosis "should not be delayed" ¹. There are no data on cosyntropin in human milk, and the label's indication covers pediatric patients ¹.

No animal studies of cancer risk, mutation or fertility have been done ¹. The two meta-analyses report accuracy, not adverse events ⁵, ⁴.

In sport

WADA, the World Anti-Doping Agency, names cosyntropin on its 2026 Prohibited List under its international name, tetracosactide ¹⁴, ⁶. Section S2.2.2 reads, in full: "Corticotrophins and their releasing factors, e.g. corticorelin and tetracosactide" ¹⁴. Class S2, "Peptide hormones, growth factors, related substances, and mimetics," is "prohibited at all times (in- and out-of-competition)" ¹⁴.

What JumpstartMD offers

JumpstartMD does not prescribe cosyntropin. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

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Compounded medications are not FDA-approved, and FDA does not review their safety, effectiveness, or quality before they are marketed. A licensed clinician decides after an evaluation whether a peptide is appropriate for you, and not every patient will qualify.