moleculefinder

Promethazine

C17H20N2S284.4 g/mol Calculated

Also called proazamine.

A sedating antihistamine used for allergy, motion sickness, nausea and, in combination syrups, cough.

Sources and notes
  • The introductionfrom sourceMoleculeFinder curated
  • Other namesfrom sourceWikidataIts English label and aliases on Wikidata.
  • Formula and weightcomputedPubChem
  • 2D drawingcomputedPubChem structure, drawn by RDKit
  • 3D modelfrom sourcePubChem 3D conformerLoaded after the page has painted, and on a phone only when you ask for it; the 2D drawing shows until it arrives.

Where you encounter it

Dispensed on prescription, not sold on a shelf. Promethazine on the product labels we hold.

Medicines

PhenerganAdded by the makerActive ingredient

Every product and list we hold

Sources and notes
  • The product labels and their strengthsfrom sourceDailyMed (FDA label)Each label lists the molecule as an ingredient, and an active ingredient at the strength shown.
  • How it gets therefrom sourceMoleculeFinder curatedEach mark is set by hand on our lists, never inferred; a label's ingredient is added by the maker. A row with no mark data says Not marked.
  • The line abovefrom sourceMoleculeFinder curatedFrom the group the molecule belongs to.

Explore its structure

Choose a part to light it up.

A nitrogen bonded to three carbons, with no hydrogen of its own. Its spare pair of electrons can still pick up a hydrogen ion, so a tertiary amine is a base.

From: standard chemistry.

Sources and notes
  • The drawingcomputedPubChem structure, drawn by RDKitThe page's one shipped drawing, with the chosen part lit in amber under it.
  • The partscomputedFound by ruleEach part is found by a chemical pattern, never picked by hand atom by atom; its words say where they come from.

Properties and sources

Calculated by PubChem

Molecular formula
C17H20N2S
Molecular weight
284.4 g/mol
XLogP3octanol/water, log units
4.8
Polar surface areatopological
31.8 Ų
H-bond donors
0
H-bond acceptors
3
Rotatable bonds
3
Complexity
298

Measured LD50, HSDB via PubChem

580 mg/kg pure promethazine, rabbit, oral

An LD50 is an animal study measurement, not a dose for a person.

Reported Hazard label (GHS), ECHA via PubChem

Danger Corrosive pictogram (GHS05), Irritant pictogram (GHS07) and Environmental pictogram (GHS09); hazard statements H302, H317, H318, H319, H410, H411

Reported Licence

The US Food and Drug Administration licenses Promethazine for human use (ANDA 083312, authorized September 19, 1973). Drugs@FDA

Groups it belongs to

Category
Prescription medicine
Family
Antihistamines
Chemical groups
Aromatics
Elements
Nitrogen, Sulfur
Hazard classes
Corrosive, Irritant, Environmental hazard, GHS Danger
SMILESCC(CN1C2=CC=CC=C2SC3=CC=CC=C31)N(C)C

PubChem CID 4927 · Wikidata Q422970 · InChIKey PWWVAXIEGOYWEE-UHFFFAOYSA-N · Data refreshed

How MoleculeFinder sources and labels its data

Questions
What is Promethazine?
A sedating antihistamine used for allergy, motion sickness, nausea and, in combination syrups, cough.
How toxic is Promethazine?
The reported LD50 of Promethazine is 580 mg/kg (rabbit, oral). An LD50 is an animal study measurement, not a dose for a person. Its GHS hazard label carries the signal word Danger and the hazard pictograms Corrosive, Irritant and Environmental. from sourcefrom source
What kind of molecule is Promethazine?
Promethazine has the formula C17H20N2S and a molecular weight of 284.4 g/mol. MoleculeFinder files it under antihistamines, in the prescription medicine group. from sourcefrom sourcefrom sourcefrom source
What else is Promethazine called?
Promethazine is also called proazamine. from source
Who licenses Promethazine as a medicine?
The US Food and Drug Administration licenses Promethazine for human use (ANDA 083312, authorized September 19, 1973). from source
Sources and notes
  • Calculated valuescomputedPubChemComputed from the structure, so no laboratory conditions apply; complexity is PubChem's own structural score.
  • LD50from sourceHSDB via PubChemOther values the sources report: rabbit, intravenous, 19 mg/kg; mouse, intravenous, 40 mg/kg; mouse, another route, 175 mg/kg. The page shows the one LD50 the site uses everywhere.
  • Hazard labelfrom sourceECHA via PubChemThe label combines these classifications.
  • ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
  • Licencefrom sourceDrugs@FDARead 2026-10-21.
  • Data refreshedfrom sourceMoleculeFinder2026-11-09

Keep exploring

Both carry an aromatic ring.ChlorpromazineC17H19ClN2S
Sources and notes
  • Similar in shapecomputedRDKit Morgan/TanimotoNeighbours by structural fingerprint; the sentence names the chemical groups the two share.
  • The drawingscomputedPubChem structures, drawn by RDKit