CHLORAMPHENIRAMINE 4MG TABS
CHLORAMPHENIRAMINE
What it does
Chlorampheniramine is an antihistamine that helps relieve allergy symptoms.
Commonly used for: allergic rhinitis (hay fever), itching, runny nose, sneezing …
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Source: Pharmacy and Poisons Board · fetched 2026-01-28 20:15:54 · updated 2026-08-03 04:16:15
About this medicine
Chlorampheniramine is an antihistamine that helps relieve allergy symptoms.
What it treats
- allergic rhinitis (hay fever)
- itching
- runny nose
- sneezing
- hives (urticaria)
How it works
It blocks the effects of histamine, a substance in the body that causes allergic symptoms.
Who it's for
Chlorampheniramine is for adults and children experiencing allergy symptoms.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: chlorampheniramine
Chlorampheniramine is an antihistamine that is commonly used to relieve symptoms associated with allergic reactions, such as hay fever, urticaria, and allergic conjunctivitis. It works primarily by blocking the action of histamine at the H1 receptor sites, which helps to alleviate symptoms such as sneezing, itching, and runny nose. Chlorampheniramine is available in various formulations including tablets, syrups, and nasal sprays.
Indications
- Allergic rhinitis (hay fever)
- Urticaria (hives)
- Allergic conjunctivitis
- Common cold symptoms
Dosage
Children: Refer to BNF for Children for appropriate dosing information.
Adults: Refer to BNF for appropriate dosing information.
Mechanism of action
Chlorampheniramine acts as a competitive antagonist of the H1 histamine receptor. By binding to these receptors, it prevents histamine from exerting its effects, thereby reducing allergy symptoms. Additionally, it has some degree of anticholinergic activity, which can contribute to its efficacy in alleviating symptoms such as rhinorrhea.
Pharmacodynamics
Chlorampheniramine has a rapid onset of action and provides symptomatic relief from allergic conditions. Its antihistamine effects can last for several hours, making it suitable for once or twice daily dosing depending on the formulation and severity of symptoms. The anticholinergic properties may lead to sedation and dry mucous membranes, which can be beneficial in certain cases but may also pose risks in sensitive populations.
Pharmacokinetics
Chlorampheniramine is well absorbed from the gastrointestinal tract, with peak plasma concentrations occurring 1-2 hours post-administration. It is extensively metabolized in the liver, primarily through glucuronidation, and has a half-life of approximately 12-15 hours. The drug is excreted mainly in the urine, with both unchanged drug and metabolites present.
Contra-indications
- Hypersensitivity to chlorampheniramine or any component of the formulation
- Severe liver impairment
- Porphyria
- Use in neonates is contraindicated due to the risk of 'grey baby syndrome'
Adverse effects
- Drowsiness
- Dizziness
- Dry mouth
- Constipation
- Blurred vision
- Urinary retention
- Allergic reactions including rash and anaphylaxis
Interactions
- CNS depressants may enhance sedative effects
- Monoamine oxidase inhibitors (MAOIs) can increase the risk of hypertensive crisis
- Anticholinergic drugs may increase the risk of adverse effects
- Alcohol may enhance drowsiness and impairment
Precautions
- Use with caution in patients with glaucoma
- Prostatic hypertrophy
- Epilepsy or seizure disorders
- Patients with cardiovascular disease
- Elderly patients may be more sensitive to effects
Pregnancy
Chlorampheniramine is generally not recommended during pregnancy, especially in the first trimester, due to potential risks to the fetus.
Breast-feeding
Chlorampheniramine is excreted in breast milk; caution is advised in nursing mothers as it may cause sedation in infants.
Storage
Store in a cool, dry place away from direct sunlight. Keep out of reach of children.
Formulations
- Tablets
- Syrup
- Oral suspension
- Injectable form
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.
This drug in other countries
The same active ingredient registered across other registries we cover - including different brands.