Merck Manual

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Some Antihistamines

Some Antihistamines

Drug

Degree of Anticholinergic Effects*

Degree of Drowsiness†

Nonprescription (over-the-counter)

Brompheniramine

Moderate

Some

Cetirizine

Few to none

Little to none in most people and moderate in some people

Chlorpheniramine

Moderate

Some

Clemastine

Strong

Moderate

Desloratadine

Few to none

Little to none

Diphenhydramine

Strong

Extreme

Fexofenadine

Few to none

Little to none

Loratadine

Few to none

Little to none

Prescription

Acrivastine‡

Few to none

Little to none

Azelastine

Few to none

Some

Cyproheptadine

Moderate

Some

Dexchlorpheniramine

Moderate

Some

Hydroxyzine

Moderate

Extreme

Levocetirizine

Few to none

Little to none

Mizolastine

Few to none

Little to none

Promethazine

Strong

Extreme

* Anticholinergic effects include dry mouth, blurred vision, constipation, difficulty with urination, confusion, and light-headedness (particularly after a person stands up). Older people are particularly susceptible to these effects.

† The degree of drowsiness varies, depending on the dose, other active ingredients in the formulation (as in formulations that contain a decongestant plus an antihistamine), and the person.

‡ Acrivastine is available only in combination with pseudoephedrine (a decongestant). The combination is taken by mouth.