General medical words
What Is an Alkaloid? Plant-Based Medicine Chemicals
Alkaloid · say it: AL-kuh-loydAlso written: alkaloids, plant alkaloid, ergot alkaloids, vinca alkaloids, belladonna alkaloids
Short answer
An alkaloid is a natural nitrogen-containing chemical, usually from plants, such as morphine, caffeine, quinine or colchicine.
What it means
Alkaloids are a large group of natural chemicals, mostly from plants, that contain nitrogen and often have strong effects on the body. Familiar examples include caffeine, nicotine, morphine and codeine (from the opium poppy), quinine (from cinchona bark), atropine (from belladonna), colchicine and the vinca alkaloids used in some cancer treatments.
Labels use the word in a few ways. A medicine may be described as 'an alkaloid' or 'belladonna alkaloids' in its description. Labels for some medicines warn against combining them with 'ergot alkaloids' (such as ergotamine, used for migraine), because certain medicines can raise their levels and cause dangerous narrowing of blood vessels.
'Natural' does not mean mild: many alkaloids are powerful and can be toxic at the wrong dose. The word describes a type of chemical, not how safe or strong a medicine is.
Where you may see it
- Medicine label 'Description' sections
- 'Contraindications' sections mentioning ergot alkaloids
- Cancer treatment information on vinca alkaloids
📄 How it looks on a report
Coadministration with ergot alkaloids is contraindicated due to the potential for serious and/or life-threatening reactions.
🙅 What it does not mean
- Natural plant origin does not make an alkaloid safe or gentle.
- Seeing 'alkaloid' on a label is not a warning by itself; it describes the chemical type.
- Not all alkaloids are related in effect; caffeine and morphine act very differently.
🗒️ Questions to ask your doctor
🧾 Reports where you will see “Alkaloid”
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💊 Medicines whose labels mention “Alkaloid”
Plain-English explanations of each medicine, from its official FDA label.
- Colchicine
an alkaloid medicine, a compound obtained from the autumn crocus plant (colchicum autumnale)
- Fluconazole
an azole antifungal medicine, a type of medicine that treats fungal (yeast) infections
🔗 Read more from trusted sources
- “Alkaloid” on MedlinePlus ↗
US National Library of Medicine
- NCI Dictionary definition ↗
US National Cancer Institute: “alkaloid”
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.