Drug reference

Clemastine

Antihistamine · Allergy Relief

Also known as Clemastine hydrogen fumarate, Tavegil, TAVIST

AntihistamineAllergy Relief

CDSCO approved

EXCRETION

—

not curated

INTERACTIONS

6 major

SEVERE in our sources

PREGNANCY

Most manufacturers of antihistamines advise avoiding their use during pregnancy; however, there is no evidence of teratogenicity. Use in the latter part of the third trimester may cause adverse effects in neonates such as irritability, paradoxical excitability, and tremor.

FDA category + note

Top interactionssee all 6 →

DextropropoxypheneSevereDatabaseDDInter
Potassium ChlorideSevereDatabaseDDInter
Potassium CitrateSevereDatabaseDDInter
Sodium OxybateSevereDatabaseDDInter

Mechanism

Clemastine is a first-generation H1 receptor antagonist. It competitively blocks the action of histamine at H1 receptors, thereby preventing histamine-mediated effects such as vasodilation, increased capillary permeability, and smooth muscle contraction. This action helps to alleviate symptoms of allergic reactions like itching, sneezing, and rhinorrhea.

Indications

Symptomatic relief of allergy such as hay feverUrticaria

Dosing

Adult: BY MOUTH: 1 mg twice daily, increased if necessary up to 6 mg daily
Max dose: 6 mg daily

Pharmacokinetics

Duration

4-6 hours

Contraindications

Acute porphyrias

Side effects

Common

AstheniaSedationdiminished alertnesslight headednessmotor incoordinationfatiguetendency to fall asleepdry mouthalteration of bowel movementurinary hesitancyblurring of vision

Serious

Abdominal pain
Agitation
Constipation
Dry mouth
Dyspnoea
Headache
Nausea
Palpitations
Rash
Tachycardia

Pregnancy & lactation

Pregnancy

Lactation

Most antihistamines are present in breast milk in varying amounts; although not known to be harmful, most manufacturers advise avoiding their use in mothers who are breast-feeding.