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Pyrilamine

Published: July 26, 2026Updated: August 25, 2026

Pyrilamine is a first-generation antihistamine used to relieve symptoms of allergies, hay fever, and the common cold. It works by blocking histamine H1 receptors, reducing allergic reactions such as sneezing, itching, watery eyes, and runny nose. Due to its sedative properties, it is sometimes included in over-the-counter sleep aids and combination products.

Quick summary

Pyrilamine is an antihistamine that treats allergy symptoms like sneezing and itching by blocking histamine receptors, but causes drowsiness.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

ATC
atc-d04
RxNorm
1113
Generic
Pyrilamine
Class
atc-d04
Brands
Pamprin Multi-Symptom, Premsyn PMS, Ninjacof, Ninjacof A, Vanacof AC, Pediaclear, Poly Hist PD
Availability
otc
Pregnancy
B
Lactation
caution
Half-life (h)
2.5
Onset (min)
30
Duration (h)
6
Routes
oral, topical, nasal
Forms
tablet, capsule, syrup, liquid, cream, nasal spray
Regions
United States, Canada, United Kingdom, Australia, Europe, India
Monitoring
sedation, drowsiness, dry mouth, blurred vision

This page is for informational purposes only.

Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.

Dosage and administration

adult (standard)tablet
Usual dose
25-50mg every 4-6 hours
Maximum
consult physician
Frequency
every 4-6 hours as needed
Instructions
Follow physician instructions
Duration limits
as prescribed
Monitoring
standard
pediatric (children_6_and_older)tablet
Usual dose
12.5-25mg every 4-6 hours
Maximum
consult physician
Frequency
every 4-6 hours as needed
Instructions
Follow physician instructions
Duration limits
as prescribed
Monitoring
standard
geriatric (standard)tablet
Usual dose
25mg every 4-6 hours
Maximum
consult physician
Frequency
every 4-6 hours as needed
Instructions
Follow physician instructions
Duration limits
as prescribed
Monitoring
standard

Overdose information

Important overdose information
Toxic dose: Single dose that may cause serious toxicity or potentially fatal outcomes in adults
Chronic overdose: Prolonged use exceeding recommended daily doses may lead to cumulative CNS depression and anticholinergic toxicity
Immediate actions
Gastric lavage within 1-2 hours of ingestion if large dose, activated charcoal administration, supportive care, airway management
Antidote
No specific antidote exists(Treatment is supportive; no antidote will reverse pyrilamine toxicity)
Poison Control: 1-800-222-1222

Special Populations

8 groups
⚠

pregnancy

first trimester
caution
FDA Category
C
Dose Adjustment

avoid if possible

Key Recommendations

avoid use during pregnancy unless benefits outweigh risks; use only if clearly necessary

Monitor

regular prenatal monitoring

Use with caution and monitor for adverse effects.

⚠

pregnancy

third trimester
caution
FDA Category
C
Dose Adjustment

avoid close to delivery

Key Recommendations

avoid use near term; may affect fetal heart rate and cause neonatal respiratory depression

Monitor

fetal monitoring in third trimester

Use with caution and monitor for adverse effects.

✗

lactation

breastfeeding
unsafe
FDA Category
N
Dose Adjustment

discontinue breastfeeding or avoid drug

Key Recommendations

pyrnilamine is excreted in breast milk; avoid use while breastfeeding

Monitor

monitor infant for excessive drowsiness

Use of this medication in this population requires careful consideration of risks and benefits.

⚠

geriatric

elderly
caution
FDA Category
N
Dose Adjustment

reduce dose and increase dosing interval

Key Recommendations

use lower initial dose; increased sensitivity to anticholinergic effects; monitor for dizziness and sedation

Monitor

monitor for falls, confusion, and anticholinergic effects

Use with caution and monitor for adverse effects.

✗

pediatric_age

infants and toddlers
contraindicated
FDA Category
N
Dose Adjustment

do not use

Key Recommendations

do not use in children under 2 years of age; risk of severe CNS depression

Monitor

not applicable

Use of this medication in this population requires careful consideration of risks and benefits.

⚠

pediatric_age

children 2 to 12
caution
FDA Category
N
Dose Adjustment

use weight-based dosing

Key Recommendations

use with caution; may cause paradoxical excitement; avoid in children with asthma

Monitor

monitor for behavioral changes and respiratory depression

Use with caution and monitor for adverse effects.

⚠

renal_impairment

severe
caution
FDA Category
N
Dose Adjustment

reduce dose by 50%

Key Recommendations

use with caution; drug is partially excreted renally; monitor renal function

Monitor

monitor renal function and adjust dose accordingly

Use with caution and monitor for adverse effects.

⚠

hepatic_impairment

severe
caution
FDA Category
N
Dose Adjustment

reduce dose by 50%

Key Recommendations

use with caution; drug is metabolized in liver; monitor liver function

Monitor

monitor liver function tests

Use with caution and monitor for adverse effects.

Statistics and clinical data

prescribingFDA
2023

First FDA approval

Value:1940s

Historical prescribing information for pyrilamine

drug_classWHO
2023

Drug class

Value:First-generation antihistamine

Antihistamine classification

usageMedical guidelines
2023

Common uses

Value:Allergic rhinitis, motion sickness, insomnia, cold symptoms

Therapeutic applications

mechanismFDA
2023

Mechanism of action

Value:H1 receptor antagonist

Pharmacological mechanism

Pyrilamine is used to treat allergic conditions including seasonal allergies, hay fever, allergic rhinitis, urticaria (hives), and pruritus (itching). It is also found in some cold medications and sleep aids for its antihistamine and sedative effects.

Pyrilamine is a competitive antagonist at H1 histamine receptors. By blocking histamine from binding to these receptors, it prevents allergic inflammatory responses and reduces symptoms such as sneezing, itching, nasal discharge, and watery eyes.

As a first-generation antihistamine, pyrilamine commonly causes drowsiness and should be used with caution when operating machinery or driving. It may also cause dry mouth, blurred vision, and urinary retention. Alcohol and other sedatives can enhance drowsiness. This medication is generally not recommended for use in children without medical supervision.

Contraindications

Conditions and patient states where this medication should be avoided or used with caution.

Do not use (1)

ABSOLUTEhypersensitivity

Known allergy to this medication or its components

Use caution (1)

RELATIVEpregnancy

Consult healthcare provider for benefits vs risks assessment

Official drug label

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy