First-generation phenothiazine antihistamine, strongly sedating
ATC code: R06AD02 (Promethazine)
Blocker of H1, D2 receptors, anticholinergic. Strong sedation (used as hypnotic and antiemetic). High anticholinergic activity. In children <2, associated with fatal respiratory depression – black box.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Acute allergic reaction and urticaria when 2nd-generation unavailable. Per 2022 – not first-line due to strong sedation and anticholinergic effects. Limited use in adults with severe reactions accompanied by nausea or insomnia. Dose 25 mg oral or IM.
Not recommended
Promethazine while breastfeeding is undesirable. RID not precisely estimated, Hale L3 due to limited data. Infant risks marked sedation, apnea, paradoxical excitation. Due to black box on fatal respiratory depression in children <2, nursing mothers should avoid regular use. If prescribed long-term, consider a second opinion.
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Boxed warning
FDA black box: fatal respiratory depression in children <2, contraindicated at this age.
Use as indicated, avoid high doses near delivery – neonatal depression risk.
Not preferred during breastfeeding. Hale L3. Regular use not recommended. Alternatives – loratadine, cetirizine.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Promethazine is evaluated for the following indications with varying evidence strength: Urticaria (evidence tier C), Allergy during breastfeeding (evidence tier D). See the full indication matrix with dosing and citations above on this page.
Common side effects of Promethazine (≥ 1 in 100): Marked drowsiness, Dry mouth, Dizziness, Confusion. See the Safety section for uncommon and serious reactions.
FDA category C. Use as indicated, avoid high doses near delivery – neonatal depression risk.
Not preferred during breastfeeding. Hale L3. Regular use not recommended. Alternatives – loratadine, cetirizine.
Promethazine is contraindicated in: Hypersensitivity to phenothiazines; Age <2 years (FDA black box); Coma, CNS depression; Narrow-angle glaucoma; Severe renal or hepatic impairment. Full list in the Safety section.
FDA black box: fatal respiratory depression in children <2, contraindicated at this age.