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[Pharmacology](https://durgical.com/en/pharmacology/) · Class

# Ergot alkaloids

Drugs derived from the ergot fungus that cause strong, sustained contraction of the uterus and of blood vessels; used for bleeding after birth and for migraine.

Updated 2026-11-01

## What they are

Ergoline derivatives that act on serotonin and alpha-adrenergic receptors. Methylergometrine and ergometrine contract the uterus and treat postpartum haemorrhage; ergotamine narrows cranial vessels and treats migraine attacks.

## Mechanism of action

They are partial agonists or antagonists at serotonin (5-HT) and alpha-adrenergic receptors. On the uterus they cause a sustained contraction that controls bleeding; on blood vessels they cause vasoconstriction, which explains hypertension, coronary spasm and ischaemia of the limbs. They are metabolised by CYP3A4.

Target: Serotonin (5-HT) and alpha-adrenergic receptors

## Key points

- Contraindicated in hypertension and pre-eclampsia: they can cause hypertensive crises and stroke.
- Strong CYP3A4 inhibitors (macrolides, protease inhibitors, azoles) can cause severe ischaemia (ergotism).
- Contraindicated in pregnancy before birth (uterine contraction).
- Coronary vasospasm: avoid in coronary artery disease.
- Long-term use of ergotamine: fibrosis of heart valves, pleura or retroperitoneum.

## Drugs in this class

- [**Methylergometrine** Ergot derivative that causes a strong, sustained contraction of the uterus after the placenta is delivered. It raises… Serotonin 5-HT2 and alpha-adrenergic receptors of the myometrium](https://durgical.com/en/pharmacology/methylergometrine/)
- [**Ergometrine** Ergot alkaloid on the WHO essential list that contracts the uterus to control bleeding after birth. Like… Serotonin 5-HT2 and alpha-adrenergic receptors of the myometrium](https://durgical.com/en/pharmacology/ergometrine/)
- [**Ergotamine** Ergot alkaloid that narrows cranial blood vessels to stop migraine attacks. Dangerous with CYP3A4 inhibitors and… Serotonin 5-HT1B/1D receptors (and alpha-adrenergic receptors)](https://durgical.com/en/pharmacology/ergotamine/)

## Others in the class

- Dihydroergotamine
- Methysergide

## Test yourself

Think of the answer, then tap the question to see it.

## Why are ergot alkaloids avoided in pre-eclampsia?

They constrict blood vessels and can cause sudden hypertension, seizures and stroke.

## Which group of antibiotics should not be combined with ergot alkaloids, and why?

Macrolides such as clarithromycin or erythromycin: they inhibit CYP3A4, ergot levels rise and severe ischaemia (ergotism) can occur.

## Which ergot alkaloid is used for migraine rather than for bleeding after birth?

Ergotamine.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - METHYLERGONOVINE MALEATE injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a9a3079e-b62b-4858-920e-d8f5cb38481e) (DailyMed (U.S. National Library of Medicine), 2026); [DailyMed - ERGOTAMINE TARTRATE AND CAFFEINE tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=41f88ae7-c124-5b9c-e054-00144ff88e88) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=G02AB) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Source: https://durgical.com/en/pharmacology/classes/ergot-alkaloids/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/ergot-alkaloids/