Clemastine
Clemastine is a first-generation antihistamine used to treat allergic conditions such as hay fever, allergic rhinitis, and urticaria. It works by blocking histamine H1 receptors, reducing symptoms like sneezing, itching, and runny nose. This medication is available by prescription and over-the-counter in some formulations.
Clemastine is an antihistamine medication used to relieve allergy symptoms like sneezing, itching, and runny nose.
Key facts at a glance
- ATC
- D04AA14
- RxNorm
- 2578
- Generic
- Clemastine
- Class
- atc-d04
- Brands
- Dayhist-1, Wal-Hist 12 HR Relief, Clemasz, Clemsza, Tavist
- Availability
- rx
- Pregnancy
- B
- Lactation
- safe
- Routes
- oral
- Forms
- tablet, solution
- Regions
- US, EU, CN, JP
- Monitoring
- —
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
- Usual dose
- 2mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 1mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 1mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
9 groupspregnancy
first trimesteruse lowest effective dose
use only if clearly needed, avoid during first trimester unless benefits outweigh risks
standard prenatal monitoring
Use with caution and monitor for adverse effects.
pregnancy
third trimesteravoid close to delivery
may cause fetal tachycardia or neonatal sedation if used near term
fetal monitoring in third trimester
Use with caution and monitor for adverse effects.
lactation
breastfeedingavoid or use lowest dose
passes into breast milk, may cause infant sedation
monitor infant for excessive drowsiness
Use with caution and monitor for adverse effects.
pediatric_age
under 12 yearsnot recommended
not approved for children under 12, avoid use due to sedation and anticholinergic effects
monitor for sedation and anticholinergic effects
Use with caution and monitor for adverse effects.
geriatric
elderlystart with lower dose
use with caution due to increased sensitivity to sedation, anticholinergic effects, and fall risk
monitor for sedation, confusion, and fall risk
Use with caution and monitor for adverse effects.
renal_impairment
mild to moderateno adjustment typically needed
use with caution, monitor renal function
periodic renal function monitoring
Use with caution and monitor for adverse effects.
renal_impairment
severereduce dose or increase interval
reduce dose or use less frequently in severe renal impairment
regular renal function monitoring
Use with caution and monitor for adverse effects.
hepatic_impairment
mild to moderateuse with caution
use with caution, may require dose adjustment
monitor liver function
Use with caution and monitor for adverse effects.
hepatic_impairment
severereduce dose
use with caution in severe hepatic impairment, consider dose reduction
regular liver function monitoring
Use with caution and monitor for adverse effects.
Statistics and clinical data
Commonly prescribed since
General prescribing information
Drug class
Drug class information
Common uses
Common therapeutic uses
Mechanism of action
Pharmacological mechanism
Treatment of seasonal and perennial allergic rhinitis (hay fever), allergic conjunctivitis, urticaria (hives), and other allergic skin conditions causing itching or rash.
Blocks histamine H1 receptors in the body, preventing histamine from binding and causing allergic symptoms. It also has anticholinergic properties that help reduce nasal secretions and has mild sedative effects.
May cause drowsiness; avoid alcohol and operating machinery until aware of effects. Use with caution in patients with glaucoma, urinary retention, or thyroid disorders. Not recommended for use in newborns or premature infants. May interact with other sedating medications or MAO inhibitors.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
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.
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 24, 2026. · Read our editorial policy