Understanding Ergot Alkaloids and Their Uses

Medications That Have a Variety of Uses

Ergot alkaloids include a group of medicines used to treat severe headaches and other conditions. Two major types of substance contain ergot alkaliods—naturally occurring chemicals and manufactured drugs. The naturally occurring chemicals are produced by fungal contamination of plants. The fungus can cause health problems if it’s consumed.

The manufactured drugs include a variety of prescription medications used to prevent bleeding during labor and delivery, for the treatment of headaches, Parkinson’s disease, dementia, and to create the recreational synthetic drug LSD (lysergic acid diethylamide), which causes hallucinations.

This article describes types of ergot alkaloids, their uses, and their side effects and toxicity. 

Rye grain with ergot

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What Are Ergot Alkaloids? 

The chemicals that are considered ergots are ergometrine, ergotamine, and ergosine. They can naturally occur, potentially leading to ergot poisoning, or they can be manufactured. 

Ergot Fungus

Ergot alkaloids are produced by Claviceps purpurea, a fungus that can grow on certain plants. Eating foods that contain rye grains that have been contaminated with ergot chemicals can cause a toxic reaction due to vasoconstriction (narrowing of the blood vessels).

The physical effects may include skin changes, tiredness, and confusion and may progress to gangrene. Gangrene is the death of tissue. When it’s due to ergot poisoning, it’s caused by narrowing of the blood vessels in the hands and feet.

Another type of ergot poisoning causes hallucinations and convulsions.

Ergot Poisoning Symptoms

Ergot poisoning due to contamination can cause:

  • Confusion
  • Fatigue
  • Gangrene
  • Convulsions
  • Hallucinations

What Are Ergot Alkaloids Used For? 

When used for medical treatment, different ergot alkaloids have different uses.

Migraines, including Migranal (dihydroergotamine), Cafergot (ergotamine): When used as a migraine therapy, these medications are taken during a migraine attack. They are not used on a preventative basis. 

Parkinson’s disease, including Parlodel, (bromocriptine), Permax (pergolide) and Dostinex (cabergoline): These medications are to be taken every day to control symptoms of this progressive brain disorder. They have also been prescribed for treating Tourette’s syndrome and certain types of pituitary tumors.

Dementia, including Hydergine (dihydroergotoxine mesylate): This medication, which is approved by the Food and Drug Administration (FDA) for the treatment of Alzheimer's disease, is prescribed for use on a daily basis to prevent the progression of dementia.

During labor and delivery, including Methergine (methylergometrine): This medication is used along with Pitocin (oxytocin) to promote uterine contractions and speed up labor. The ergot constricts (narrows) the blood vessels of the uterus the prevent excessive bleeding.

Side Effects

Caution is necessary when using ergot alkaloid therapies. These medications narrow the blood vessels, which can cause adverse effects. The side effects are not the same for each of the ergot medications. 

Side effects of ergots used for treating dementia include:

  • Nausea
  • Abdominal discomfort

Potential adverse effects of ergots used for treating migraines include:

  • Rebound headaches (medication overuse headaches)
  • Angina or heart attack 
  • Stroke
  • Harm to the fetus during pregnancy

Potential adverse effect of bromocriptine:

  • Heart valve disease 

If you are prescribed an ergot alkaloid, make sure you are familiar with the early signs of harmful effects of the medication that you’re taking so you can get medical attention if you develop warning signs.  


The formulations and doses vary widely for ergot drugs. Most are available in oral tablet or liquid form.

Additionally, some ergots for treating migraine are available in forms that can be inhaled or injected, which can be helpful for people who are having a hard time taking a liquid or pill due to nausea. Ergot treatments in labor and delivery are used intravenously (injected in a vein, IV).

Usually, ergot treatments are used regularly to prevent symptoms, such as when prescribed for treatment of Alzheimer’s dementia or Parkinson’s disease. When treating migraines, these medications are prescribed for use as needed, with limits on number take in a given amount of time.

When used during labor and delivery, the intravenous form of ergot alkaloid is given only during a short period of time.

Contraindications and Precautions

Because of their potential for adverse effects, ergot alkaloid medications are not appropriate for everyone. If you have certain conditions that put you at a high risk of harmful side effects, you would not be prescribed one of these medications. 

The contraindications—reasons not to take a certain treatment—are specific for each ergot drug.

Examples of contraindications:

  • All of the ergot medications should not be used (or should be used with extreme caution) if you've previously had an adverse reaction to an ergot drug.
  • Ergot drugs used for the treatment of migraine should not be taken when pregnant or if you have cardiovascular risk factors.
  • Ergot drugs used for the treatment of Parkinson’s disease should not be used if you have heart disease or lung disease.

Ergot Alkaloids and Drug Interactions

Ergot alkaloids are potent drugs, and they have many drug interactions. Each of the ergot alkaloids interacts with a specified set of medications. It’s crucial to tell your healthcare provider and pharmacist about all medical conditions you have, as well as all medications (even over-the-counter medications), supplements, vitamins, and herbs that you are using.


Ergot alkaloids are substances found in medications for treating migraines, Parkinson's disease, Alzheimer's disease, and prevention of excessive bleeding during labor and delivery. LSD, a hallucinogenic drug, is derived from ergot chemicals.

Eating food that's been contaminated with an ergot-producing fungus can cause ergot poisoning, which involves a variety of side effects, including gangrene (tissue death) due to the severe narrowing of blood vessels causing a loss of blood supply to a part of the body.

A Word From Verywell

Ergot alkaloids have been known for many years as toxins that can cause poisoning, and as medication or drugs of abuse. If you are prescribed an ergot alkaloid by your healthcare provider, take it as directed, and rest assured that your dose and prescription are safe for you.

As with any medical treatment, make sure you are familiar with the potentially harmful side effects and adverse effects so you can get medical attention if you need it. 

Frequently Asked Questions

  • Are ergot alkaloids helpful for migraines?

    There are several migraine medications that are ergot alkaloids. These include Cafergot and Migranal. They can be effective, but they are not commonly prescribed because of their potential side effects.

  • What are the effects of ergot fungus in humans?

    This condition has been called Saint Anthony’s fire, among other names. The effects of ergot fungus poisoning include:

    • Fatigue 
    • Confusion 
    • Skin changes 
    • Gangrene 
    • Hallucinations
    • Convulsions
  • Are ergot alkaloids safe in pharmacology?

    Yes, when they are used according to guidelines and recommendations, ergot alkaloids are safe. This means proper dosing and avoiding use with medications or supplements that can induce interactions.

    Ergot alkaloids can cause side effects and adverse reactions, especially when they are used by people who have certain risk factors, such as heart disease. Even when used properly, these medications have the potential to cause serious side effects.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.