Leader Allerhist Side Effects
Generic name: clemastine
Note: This document contains side effect information about clemastine. Some of the dosage forms listed on this page may not apply to the brand name Leader Allerhist.
Some side effects of Leader Allerhist may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to clemastine: oral syrup, oral tablet
Stop taking clemastine (the active ingredient contained in Leader Allerhist) and seek emergency medical attention if you experience an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives).
Other, less serious side effects may be more likely to occur. Continue to take clemastine and talk to your doctor if you experience
sleepiness, fatigue, or dizziness;
dry mouth; or
difficulty urinating or an enlarged prostate.
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.
For Healthcare Professionals
Applies to clemastine: compounding powder, oral syrup, oral tablet
Nervous system side effects have included central nervous system depression which has commonly resulted in drowsiness, dizziness, and headache. Dyskinesias have rarely been reported following chronic use of antihistamines.
Nearly all patients experience drowsiness. This drowsiness may subside in some patients with extended use. Patients should be warned against driving, as well as concomitant ingestion with alcohol and other sedative-hypnotic drugs.
Few cases of dyskinesias and tremors, often of the face, have been reported in patients whose chronic use of antihistamines extended over a period of 3 to 10 years. Some of these cases were only partially relieved by discontinuation of the drug. Haloperidol was successful in relieving symptoms.
Gastrointestinal side effects have included dry mouth and constipation due to anticholinergic effects. This has occurred in up to one-third of patients.
Cardiovascular side effects have included hypotension, tachycardia, and palpitations.
Ocular effects are due to the anticholinergic effects and may include blurred vision, diplopia, and dry eyes.
Genitourinary side effects have included dysuria, urinary hesitancy, decrease in urine flow, and in rare cases, acute urinary retention.
Hematologic side effects that have been reported with antihistamines include bone marrow suppression, thrombocytopenia, and aplastic anemia.
A fatal case of agranulocytosis has been reported in a patient taking chlorpheniramine, pseudoephedrine, acetaminophen, dextromethorphan, phenylpropanolamine, and aspirin. Chlorpheniramine was felt to be the cause.
Respiratory side effects have included thickening of bronchial secretions, wheezing, and tightness in the chest.
At least one case of toxic pustuloderma has been reported during clemastine (the active ingredient contained in Leader Allerhist) therapy.
Dermatologic side effects have included toxic pustuloderma.
More Leader Allerhist resources
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