What Happens When You’re Just Mind Blanking
December 27, 2025
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Brand Name :
Tavist Allergy, Tavist-1, Allerhist-1, Dailyhist-1, Contac 12 Hour Allergy
Synonyms :
clemastine
Class :
First Generation, Antihistamines
Brand Name :
Tavist Allergy, Tavist-1, Allerhist-1, Dailyhist-1, Contac 12 Hour Allergy
Synonyms :
clemastine
Class :
First Generation, Antihistamines
Dosage Forms & Strengths
Syrup
0.67mg/5ml
Tablet
1.34 mg
2.68 mg
Take dose of 1.34 mg orally every 12 hours and a maximum daily dose up to 8.04 mg for syrup or 2.68 mg for tablets
Take dose of 2.68 mg orally daily every 8 hours and a maximum daily dose up to 8.04 mg
Dosage Forms & Strengths
Syrup
0.67mg/5ml
Tablet
1.34 mg
2.68 mg
<6 years old: take 0.05 mg/kg daily as clemastine base divided every 8 to 12 hours and dose not more than 1.34 mg
6 to 12 years old: take 0.67 to 1.34 mg clemastine fumarate every 12 hours and a daily dose not more than 4.02 mg
>12 years old: follow dose as per adults
<6 years old: take 0.05 mg/kg daily as clemastine base divided every 8 to 12 hours and dose not more than 1.34 mg
6 to 12 years old: take 0.67 to 1.34 mg clemastine fumarate every 12 hours and a daily dose not more than 4.02 mg
>12 years old: follow dose as per adults
Refer to adult dosing
it may enhance the risk of QTc prolongation when combined with amifampridine
MAO inhibitors increase the anticholinergic action of clemastine
MAO inhibitors increase the anticholinergic action of clemastine
MAO inhibitors increase the anticholinergic action of clemastine
MAO inhibitors increase the anticholinergic action of clemastine
MAO inhibitors increase the anticholinergic action of clemastine
When clemastine is used together with medazepam, the risk or seriousness of CNS depression is enhanced
When clemastine is used together with levosulpiride, the risk or seriousness of CNS depression is enhanced
When clemastine is used together with melitracen, this leads to enhanced risk or seriousness of CNS depression
When ponesimod is used together with clemastine, this leads to enhanced risk or seriousness of bradycardia
When clemastine is used together with aenosine, this leads to enhanced risk or seriousness of QTc prolongation
When clemastine is used together with givinostat, this leads to enhanced risk or seriousness of Qtc prolongation
When emylcamate is used together with clemastine, this leads to enhanced risk or seriousness of CNS depression
When acepromazine is used together with clemastine, this leads to enhanced risk or seriousness of CNS depression
may increase the effects of pharmacodynamic synergism
Actions and Spectrum
clemastine inhibits histamine’s ability to attach to H1 histamine receptors, preventing the allergic reactions that histamine causes.
By inhibiting acetylcholine’s ability to activate muscarinic receptors, clemastine demonstrates anticholinergic effect.
Sneezing, itching, runny nose, and nasal congestion are just a few of the allergic rhinitis symptoms that clemastine is frequently used to treat.
Frequency not defined
CNS depression
Dysuria
Urinary retention
Disturbed coordination
Anorexia
Leukopenia
Pancytopenia
Impotence
Vertigo
Diarrhea
Wheezing
Chills
Thrombocytopenia
Muscular weakness
Nervousness, delirium, palpitation, seizures, restlessness, insomnia, tremors, euphoria is less common
Dizziness
Visual disturbances
Acute labyrinthitis
Palpitation ECG changes, Arrhythmias, Tachycardia
Tightness of the chest
Hypotension
Blurred vision
Diplopia, tinnitus
Hypertension
Facial dyskinesia
Nasal stuffiness
Toxic psychosis
Headache
Sweating
Thickening of bronchial secretions
Hypotension, dizziness and sedation may occur in geriatric patients
Dryness of mouth, throat and nose
Lassitude
Paresthesia
Hemolytic anemia
Early menses
Faintness
Agranulocytosis
Nervousness
Irritability
Nausea
Vomiting
Cholestasis, hepatic function abnormality, jaundice, hepatitis, hepatic failure is rare
Insomnia
Tremors
Pruritus, inflammation, rash, eczema, erythema on exposed skin may occur with topical formulation
Constipation
Epigastric distress
Drowsiness
Sedation ranging from mild drowsiness to deep sleep
Black Box Warning
None
Contraindication/Caution:
Contraindication:
Caution:
Pregnancy warnings:
Pregnancy category: B
Lactation: Enters human breast milk and it is not recommended
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
First-generation antihistamine with anticholinergic effects is clemastine.
At H1 histamine receptors, clemastine functions as a competitive antagonist.
Pharmacodynamics
clemastine exhibits anticholinergic effects by blocking the action of acetylcholine on muscarinic receptors. The H1 histamine receptor is specifically blocked by clemastine.
Sedation is produced when clemastine interacts with central histamine receptors after crossing the blood-brain barrier.
Pharmacokinetics
Absorption
It is well absorbed from the gastrointestinal tract after oral administration.
Distribution
clemastine has a high plasma protein binding capacity, primarily binding to albumin.
Metabolism
clemastine undergoes extensive hepatic metabolism.
Elimination and excretion
clemastine and its metabolites are primarily eliminated through renal excretion.
Administration
clemastine is administered orally in the form of tablets or syrup.
Patient information leaflet
Generic Name: clemastine
Why do we use clemastine?
clemastine is used to alleviate symptoms of allergic rhinitis, such as sneezing, itching, runny nose, and nasal congestion.
clemastine is effective in relieving symptoms associated with hives, including itching, redness, and swelling.
It can be used to alleviate symptoms of allergic conjunctivitis, such as redness, itching, and watering of the eyes.
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