Chlorpheniramine Side Effects
Some side effects of chlorpheniramine 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 chlorpheniramine: oral liquid, oral suspension extended release, oral syrup, oral tablet, oral tablet chewable, oral tablet extended release
Get emergency medical help if you have any of these signs of an allergic reaction while taking chlorpheniramine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using chlorpheniramine and call your doctor at once if you have a serious side effect such as:
fast or uneven heart rate;
tremor, seizure (convulsions);
easy bruising or bleeding, unusual weakness;
feeling short of breath; or
urinating less than usual or not at all.
Less serious side effects of chlorpheniramine may include:
dry mouth, nose, or throat;
blurred vision; or
feeling nervous or restless.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
For Healthcare Professionals
Applies to chlorpheniramine: compounding powder, injectable solution, oral capsule extended release, oral liquid, oral suspension extended release, oral syrup, oral tablet, oral tablet chewable, oral tablet extended release
Central nervous system side effects have included depression resulting in drowsiness in 75% or more of treated patients. Dyskinesias have rarely been reported following chronic use of chlorpheniramine.
Nearly all patients treated with chlorpheniramine experience drowsiness. This drowsiness may subside in some patients with extended use.
Few cases of dyskinesias and tremors, often of the face, have been reported in patients whose chronic use of chlorpheniramine 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 in up to one-third of treated patients.
Cardiovascular side effects have included hypotension, tachycardia, and palpitations.
Ocular side effects of chlorpheniramine may include blurred vision, diplopia, and dry eyes due to anticholinergic effects.
Genitourinary side effects have included dysuria, urinary hesitancy, and a decreased urine flow. In rare cases, the anticholinergic effect of chlorpheniramine has precipitated acute urinary retention.
Hematologic side effects have included 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.
More chlorpheniramine resources
- chlorpheniramine Concise Consumer Information (Cerner Multum)
- chlorpheniramine MedFacts Consumer Leaflet (Wolters Kluwer)
- Aller-Chlor syrup MedFacts Consumer Leaflet (Wolters Kluwer)
- Chlorpheniramine Maleate, Dexchlorpheniramine Maleate Monograph (AHFS DI)
- Ed ChlorPed suspension drops MedFacts Consumer Leaflet (Wolters Kluwer)
- Pediox-S suspension MedFacts Consumer Leaflet (Wolters Kluwer)
- QDALL AR sustained-release capsules MedFacts Consumer Leaflet (Wolters Kluwer)
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