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Potentially life-threatening emergency
Ergotism - Skin
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Potentially life-threatening emergency

Ergotism - Skin

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Contributors: Laurie Good MD, Jeffrey D. Bernhard MD, Noah Craft MD, PhD, Lindy P. Fox MD, Lowell A. Goldsmith MD, MPH, Michael D. Tharp MD
Other Resources UpToDate PubMed


Ergotism, or "St. Anthony's Fire," is a vasospastic disorder that historically resulted from ingestion of ergot, which is produced by a rye-wheat fungus called Claviceps purpurea. Modern ergotism is most commonly the result of toxic ingestion of ergotamine alkaloids, which are used in the treatment of migraines, or toxicity from a combination of ergot-containing substances (caffeine, cigarettes, and ergotamine alkaloids). Modern ergotism is very rare (0.001-0.002% of people taking an ergot-derived medication are affected), but all clinicians should be aware of such medications' association with ergotamine toxicity.

Ergotism can take two forms: convulsive (neurologic) and gangrenous (ischemic). Convulsive ergotism shares many clinical features with serotonin syndrome, while gangrenous ergotism is a form of dry gangrene due to vasoconstriction, most often of the lower limbs. While both forms existed in epidemics historically, modern ergotism is usually related to chronic toxicity from overuse of ergotamine alkaloids and typically takes the "gangrenous" (ischemic) form. Acute ergotism, although less common, can present with signs and symptoms of both convulsive and gangrenous forms.

In both convulsive and gangrenous ergotism, the initial symptoms consist of gastrointestinal disturbances, vague flu-like symptoms, and distal extremity paresthesias. In the convulsive type, the disorder then progresses to involuntary, spastic movements, opisthotonus, hallucinations, mental status changes, seizures, and even death. Symptoms can be episodic with short periods during which the patient seems unaffected.

In the gangrenous form of modern ergotism, patients are mentally intact, and peripheral vasculature is the target of the disorder, due to alpha-adrenergic stimulation. Symptoms are typically claudication and a burning sensation in the lower limbs, decreased distal pulses, and skin that is cool to the touch with a bluish discoloration in severe cases.

Perianal ulcers and even anorectal strictures and rectovaginal fistulas have been reported in association with ergotamine tartrate suppositories, which are used for migraines. Ergotamine-induced perianal ulcers are typically painless and clear up with the cessation of the medication. Local vasoconstriction is the presumed cause.


T62.94XA – Toxic effect of unspecified noxious substance eaten as food, undetermined, initial encounter

51510002 – Ergotism

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Differential Diagnosis & Pitfalls

This is a clinical diagnosis, and the index of suspicion must be high. The differential diagnosis includes all diseases associated with limb ischemia:
  • Atherosclerosis – Patients will usually have obvious risk factors that are not often present in patients with ergotism.
  • Vasculitis
  • Buerger's disease
  • Drug-induced vasospasm
  • Aneurysm
  • Thromboembolism
If the presentation involves perianal ulcers, stricture, or fistulas, the differential includes:
Ankle-brachial index (ABI) is a useful test for establishing whether the patient has ischemic disease, but it does not help pinpoint the underlying etiology. Duplex ultrasound can then be used to identify the specific cause of the ischemia. If no clots or plaques are seen, vasospasm favors an ischemic cause such as ergotism. Arteriography is the gold standard in diagnosing vasospasm, and it is also therapeutic for most cases of ergotamine-associated vasospasm.

For patients presenting with ergotamine-induced perianal ulcerations, strictures, or fistulas, a thorough history will establish frequent use of ergotamine tartrate suppositories. Infectious and neoplastic causes should be ruled out.

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Updated: 05/13/2019
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Potentially life-threatening emergency
Ergotism - Skin
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Ergotism (Convulsive) : Agitation, Altered mental state, Seizures, Fever, Dystonia, Ergot alkaloid, Fasciculations, Opisthotonic posturing, Diaphoresis, Hallucination
Clinical image of Ergotism
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