Allergy Relief Side Effects
Generic name: chlorpheniramine
Medically reviewed by Drugs.com. Last updated on Sep 21, 2022.
Note: This document contains side effect information about chlorpheniramine. Some dosage forms listed on this page may not apply to the brand name Allergy Relief.
Applies to chlorpheniramine: oral syrup, oral tablet, oral tablet extended release.
Serious side effects of Allergy Relief
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
Other side effects of Allergy Relief
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
- Feeling sleepy.
- Feeling nervous and excitable.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.
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.
Very common (10% or more): Sedation, somnolence
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.[Ref]
Common (1% to 10%): Blurred vision[Ref]
Common (1% to 10%): Nausea, dry mouth
Common (1% to 10%): Fatigue
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.[Ref]
Frequency not reported: Muscle twitching, muscle weakness[Ref]
Frequency not reported: Thickening of bronchial secretions[Ref]
Frequently asked questions
- What's the difference between Xhance and Flonase Allergy Relief?
- Is Xyzal available over-the-counter?
- Can you take antihistamines when pregnant?
More about Allergy Relief (chlorpheniramine)
- Check interactions
- Dosage information
- During pregnancy
- Drug class: antihistamines
- En español
Related treatment guides
1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Some side effects may not be reported. You may report them to the FDA.