2025 Guidelines for the Evaluation and Management of Adults With Congenital Heart Disease
December 19, 2025
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Brand Name :
Ahist
Synonyms :
chlorcyclizine
Class :
Antihistamine
Brand Name :
Ahist
Synonyms :
chlorcyclizine
Class :
Antihistamine
Dosage Forms & Strengths
Tablet
16 mg
12 mg
8 mg
4 mg
2 mg
Syrup
8 mg/5 ml
4 mg/5 ml
Take a dose of 4 mg orally every 4 to 6 hours
Maximum dose should not be more than six tablets in a day
Take a dose of 10 ml orally every 4 to 6 hours
Maximum dose should not be more than 6 doses in a day
Dosage Forms & Strengths
Tablet
16 mg
12 mg
8 mg
4 mg
2 mg
Syrup
8 mg/5 ml
4 mg/5 ml
For >12 years old:
Take a dose of 4 mg orally every 4 to 6 hours
For 6 to 12 years old:
Take a dose of one-half tablet of 4 mg orally every 4 to 6 hours
For >12 years old:
Take a dose of 10 ml orally every 4 to 6 hours
For 6 to 12 years old:
Take a dose of 5 ml orally every 4 to 6 hours
Refer to adult dosing
When ponesimod is used together with chlorcyclizine, this leads to enhanced risk or seriousness of bradycardia
When chlorcyclizine is used together with adenosine, this leads to enhanced risk or seriousness of QTc prolongation
When chlorcyclizine is used together with givinostat, this leads to enhanced risk or seriousness of Qtc prolongation
Actions and Spectrum:
Action:
As an antihistamine, chlorcyclizine works by preventing the effects of histamine, a chemical generated during allergic reactions, which helps with symptoms of allergies such as itching, sneezing, and runny nose.
Frequency not defined
Swelling of the face, lips, or tongue
Trouble passing urine
Skin rash
Itching or hives
Vision change
Black Box Warning
None
Contraindication/Caution:
Contraindication:
Hypersenstivity
Caution:
Liver or kidney disease
Narrow-angle glaucoma
Pregnancy consideration:
Pregnancy category: N/A
Lactation: Excretion into human milk is unknown
Pregnancy Categories:
Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.
Category B: There was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women.
Category C: There was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.
Category D: Adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.
Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.
Category N: There is no data available for the drug under this category.
Pharmacology
Antihistamines like chlorcyclizine also have sedative and anticholinergic effects.
Pharmacodynamics
By inhibiting histamine H1 receptors, chlorcyclizine stops allergic symptoms such as sneezing, runny nose and itching.
Pharmacokinetics
Absorption
Chlorcyclizine is absorbed in the GI tract.
Distribution
The distribution occurs throughout the body.
Metabolism
Chlorcyclizine undergoes metabolism primarily in the liver.
Excretion and Elimination
The excretion occurs through urine.
Administration
The route of administration is oral.
Patient information leaflet
Generic Name: chlorcyclizine
Why do we use chlorcyclizine?
The drug is used for treating rhinitis symptoms nasal congestion, runny nose, itching, sneezing & symptoms of pollen allergy.
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