Alimemazine: Essential Guide To Uses, Dosage, And Risks
Comprehensive guide to alimemazine: uses for itching, urticaria, sedation, off-label sleep aid in children, dosage, side effects, and precautions.
Alimemazine is a phenothiazine derivative antihistamine primarily used to treat itching (pruritus) and urticaria (hives). It also provides sedative and antiemetic effects, making it suitable for premedication before surgery and off-label management of sleep disorders in children under specialist guidance.
About Alimemazine
Alimemazine, also known as trimeprazine, belongs to the phenothiazine class of drugs. Unlike antipsychotic phenothiazines like chlorpromazine, alimemazine focuses on antihistamine, antipruritic, sedative, and antiemetic properties. It competitively antagonizes histamine at H1 receptors, reducing allergic symptoms such as itching and skin reactions.
Available in the UK as branded liquids: Alfresed (sugar-containing syrup, 7.5mg/5ml and 30mg/5ml) and Itzenal (sugar-free oral solution, 7.5mg/5ml and 30mg/5ml). These formulations are preferred for cost-effectiveness and lack of propylene glycol.
Alimemazine is not approved in the US but is licensed in the UK and other regions for specific indications. It is approved for veterinary use in some contexts.
Key Uses of Alimemazine
Pruritus and Urticaria
The primary licensed indication is prevention and relief of allergic conditions causing pruritus and urticaria. It effectively reduces itching from eczema, poison ivy, or other skin allergies by blocking histamine effects.
Sedation and Premedication
Alimemazine has a central sedative effect similar to chlorpromazine but without significant anti-adrenergic actions. It is used to reduce awareness or relax children before operations.
Off-Label Use: Sleep Disorders in Children
In South Yorkshire ICB shared care protocols, alimemazine is repurposed off-label as a second-line treatment for behavioral insomnia in children after 3-6 months of maximal melatonin fails. It is used alongside sleep hygiene and parental education. Recommended by tertiary sleep services at Sheffield Children’s Hospital (SCH).
Not age-dependent; dosing based on response. Maximum 60mg daily.
Other Uses
- Antiemetic for motion sickness prevention.
- Adjunct in cough and cold preparations (historically).
Structurally related to tricyclic antidepressants, explaining some shared side effects.
Before Taking Alimemazine
Contraindications
- Severe respiratory depression.
- Comatose states.
- Children under 1 year (risk of death from respiratory depression).
Cautions
- Parkinson’s disease, epilepsy, narrow-angle glaucoma, prostatic hypertrophy, hepatic/renal impairment, hypothyroidism, myasthenia gravis.
- Pyloro-duodenal obstruction, bladder neck obstruction.
- Cardiovascular disease, hypotension history.
- Susceptibility to angle-closure glaucoma.
- Use lowest effective dose in elderly.
Pregnancy and Breastfeeding
Avoid unless essential; potential neonatal respiratory depression, jaundice, extrapyramidal effects. Present in milk; may cause sedation/irritability in infants.
Interactions
Potentiates CNS depressants (alcohol, hypnotics, anxiolytics). Avoid with MAOIs. Increases anticholinergic effects with atropine-like drugs. May enhance QT prolongation with certain medications.
| Drug Class | Interaction |
|---|---|
| Alcohol | Potentiates CNS depression |
| Antipsychotics | Increased sedation, extrapyramidal effects |
| Antidepressants (TCAs) | Enhanced anticholinergic effects |
| Antihypertensives | Hypotension risk |
How to Take Alimemazine
Take as directed, usually orally as liquid. Shake well. Use provided measure. Take after meals to reduce drowsiness.
Dosage Guidelines
Licensed Uses (Adults)
- Pruritus/Urticaria: 10mg 2-3 times daily; intractable up to 100mg daily.
- Elderly: 10mg once or twice daily.
Premedication (Children)
- 2-7 years: Up to 2mg/kg 1-2 hours pre-procedure.
Off-Label Sleep in Children
- Start: 5mg at bedtime.
- Increase: By 2.5-5mg steps if inadequate response.
- Max: 60mg daily.
- Specialist optimizes dose (min 3 months), then transfers to primary care after 12 weeks stable.
Weaning: After 6 months, gradual reduction over 1-2 weeks during school holidays. Restart if rebound insomnia after 7-14 days.
Side Effects of Alimemazine
Common: Drowsiness, dry mouth, blurred vision, constipation, urinary retention.
Serious Side Effects
- Extrapyramidal symptoms (dystonia, akathisia, parkinsonism).
- Neuroleptic malignant syndrome (rare).
- Blood dyscrasias, photosensitivity, jaundice.
- Overdose: Severe drowsiness, seizures, hallucinations, muscle spasms, respiratory issues.
Report serious reactions immediately. Stop if adverse effects occur.
Understanding Shared Care for Off-Label Use
In shared care (e.g., South Yorkshire ICB), specialist initiates, optimizes, and monitors for 3-12 weeks. GP continues prescribing post-transfer with review. Specialist handles dose changes unless agreed.
- Treatment duration: Specialist-determined based on response.
- Monitoring: Baseline bloods, ECG if cardiac risk; annual reviews.
- Discontinuation: GP stops if serious ADR.
Overdose and Management
Symptoms: Unsteadiness, seizures, severe drowsiness, hallucinations, muscle spasms, shortness of breath. Seek emergency help. No specific antidote; supportive care (activated charcoal, ventilation).
Frequently Asked Questions (FAQs)
Is alimemazine safe for children?
Yes for licensed uses over 1 year; off-label sleep under specialist only. Max 60mg daily.
What brands of alimemazine are recommended?
Alfresed (sugar syrup) or Itzenal (sugar-free).
Can alimemazine be used long-term?
For sleep, typically 6 months then wean; longer if specialist advises.
Does alimemazine cause drowsiness?
Yes, significant sedative effect; avoid driving/operating machinery.
Is alimemazine available over-the-counter?
No, prescription only.
Patient Resources
- Sleep hygiene advice from SCH tertiary services.
- MHRA Yellow Card for side effect reporting.
References
- South Yorkshire ICB Shared Care Protocol for Alimemazine — South Yorkshire Integrated Care Board. 2023. https://mot.southyorkshire.icb.nhs.uk/south-yorkshire/files/South%20Yorkshire%20Shared%20Care%20Alimemazine.pdf
- Alimemazine: Uses, Interactions, Mechanism of Action — DrugBank Online. 2024-01-10. https://go.drugbank.com/drugs/DB01246
- Itzenal 7.5 mg/5 ml Oral Solution SmPC — electronic Medicines Compendium (emc). 2023-05-15. https://www.medicines.org.uk/emc/product/13888/smpc
- Alimemazine Dosage Information — MIMS Singapore. 2024. https://www.mims.com/singapore/drug/info/alimemazine?mtype=generic
- Alfresed 30mg/5ml Syrup PIL — electronic Medicines Compendium (emc). 2023. https://www.medicines.org.uk/emc/product/11999/pil
- MHRA Products: ALIMEMAZINE TARTRATE — Medicines and Healthcare products Regulatory Agency. 2025-01. https://products.mhra.gov.uk/substance/?substance=ALIMEMAZINE+TARTRATE
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