July 28, 2016
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Clemastine Fumarate Syrup

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Clemastine Fumarate Syrup

Clemastine Fumarate Syrup Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 5/26/2016

Clemastine Fumarate Syrup 0.5 mg/5 mL is an antihistamine used for the relief of symptoms associated with allergic rhinitis such as sneezing, runny nose, itching, and watery eyes. Clemastine Fumarate Syrup is available in generic form. Common side effects of Clemastine Fumarate Syrup include:

  • drowsiness
  • dizziness
  • headache
  • constipation
  • stomach upset
  • blurred vision
  • trouble walking
  • clumsiness, or
  • dry mouth/nose/throat

The starting dose of clemastine fumarate syrup is 2 teaspoonfuls (1 mg clemastine) twice daily. Dosage may be increased as required, but not to exceed 12 teaspoonfuls daily (6 mg clemastine). Clemastine fumarate syrup may interact with barbiturates, tranquilizers, alcohol, and monoamine oxidase inhibitors (MAOIs). Tell your doctor all medications and supplements you use. During pregnancy, clemastine fumarate should be taken only if prescribed. This drug passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breastfeeding.

Our Clemastine Fumarate Syrup 0.5 mg/5 mL Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Clemastine Fumarate Syrup FDA Prescribing Information: Side Effects
(Adverse Reactions)


The most frequent adverse reactions are italicized:

Nervous System

Sedation, sleepiness, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, euphoria, paresthesia, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthitis, hysteria, neuritis, convulsions.

Gastrointestinal System

Epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation.

Respiratory System

Thickening of bronchial secretions, tightness of chest and wheezing, nasal stuffiness.

Cardiovascular System

Hypotension, headache, palpitations, tachycardia, extrasystoles.

Hematologic System

Hemolytic anemia, thrombocytopenia, agranulocytosis.

Genitourinary System

Urinary frequency, difficult urination, urinary retention, early menses.


Urticaria, drug rash, anaphylactic shock, photosensitivity, excessive perspiration, chills, dryness of mouth, nose and throat.

Read the entire FDA prescribing information for Clemastine Fumarate Syrup (Clemastine Fumarate Syrup)

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Allergies & Asthma

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