Chlorpheniramine 12mg CR Tablets
It is used to ease allergy signs.
Drug Class
Antihistamine
Pharmacologic Class
H1 Receptor Antagonist (First-Generation)
Pregnancy Category
B
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Chlorpheniramine is an antihistamine used to relieve symptoms of allergies like sneezing, runny nose, itchy eyes, and watery eyes. The 'CR' or 'Extended-Release' means it's designed to work for a longer period, typically 12 hours, so you don't have to take it as often.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If it causes stomach upset, take it with food to help minimize this side effect. It's essential to swallow the medication whole and not chew, break, or crush it.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry location, avoiding the bathroom. Keep all medications in a safe place, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Avoid taking two doses at the same time or taking extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If it causes stomach upset, take it with food to help minimize this side effect. It's essential to swallow the medication whole and not chew, break, or crush it.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry location, avoiding the bathroom. Keep all medications in a safe place, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Avoid taking two doses at the same time or taking extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
Lifestyle & Tips
- Avoid alcohol and other sedating medications while taking this drug.
- Be cautious when driving or operating machinery until you know how this medication affects you.
- Drink plenty of fluids to help with dry mouth.
- Avoid prolonged exposure to high temperatures, as this medication can reduce sweating and increase risk of heat stroke.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
12 mg orally every 12 hours
Dose Range:
12 - 12 mg
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not recommended for children under 12 years for 12mg extended-release formulation.
Adolescent:
12 mg orally every 12 hours (for ages 12 years and older)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed
Moderate:
Consider dose reduction (e.g., 50%)
Severe:
Significant dose reduction (e.g., 50-75%) or avoid
Dialysis:
Not significantly dialyzable; consider reduced dose based on residual renal function
Hepatic Impairment:
Mild:
No specific adjustment needed
Moderate:
Consider dose reduction (e.g., 50%)
Severe:
Significant dose reduction (e.g., 50-75%) or avoid
Pharmacology
Mechanism of Action
Chlorpheniramine is a first-generation antihistamine that competitively antagonizes H1 histamine receptors, thereby preventing histamine from binding and exerting its effects. This leads to a reduction in symptoms such as sneezing, rhinorrhea, and itching. It also possesses significant anticholinergic (antimuscarinic) properties, contributing to its drying effects and common side effects like sedation.
Pharmacokinetics
Absorption:
Bioavailability:
25-60% (variable due to first-pass metabolism)
Tmax:
6-12 hours (for extended-release formulation)
FoodEffect:
Food may delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
1-10 L/kg (highly variable)
ProteinBinding:
69-72%
CnssPenetration:
Yes (readily crosses the blood-brain barrier, contributing to sedation)
Elimination:
HalfLife:
12-43 hours (highly variable, prolonged in elderly and renal impairment)
Clearance:
Not readily available as a single rate; primarily renal excretion of metabolites.
ExcretionRoute:
Renal (urine)
Unchanged:
19-34% (variable)
Pharmacodynamics
OnsetOfAction:
30-60 minutes (for immediate release; delayed for extended-release)
PeakEffect:
6-12 hours (for extended-release)
DurationOfAction:
10-24 hours (for extended-release)
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
In rare cases, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek immediate medical attention:
- Signs of an allergic reaction, such as 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 Possible Side Effects
Like all medications, this drug can cause side effects, although not everyone will experience them. Some people may have no side effects or only mild ones. If you are bothered by any of the following side effects or if they do not go away, contact your doctor:
- Feeling sleepy
- Feeling nervous and excitable
Additional Information
This list does not include all possible side effects. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
In rare cases, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek immediate medical attention:
- Signs of an allergic reaction, such as 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 Possible Side Effects
Like all medications, this drug can cause side effects, although not everyone will experience them. Some people may have no side effects or only mild ones. If you are bothered by any of the following side effects or if they do not go away, contact your doctor:
- Feeling sleepy
- Feeling nervous and excitable
Additional Information
This list does not include all possible side effects. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe drowsiness or dizziness
- Difficulty urinating
- Blurred vision
- Rapid or irregular heartbeat
- Confusion or hallucinations
- Seizures
- Severe allergic reaction (rash, itching/swelling, severe dizziness, trouble breathing)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial to avoid potential interactions between this medication and other substances.
* Any existing health problems you have, as they may affect the safety and efficacy of this medication.
To ensure your safety, it is vital to verify that it is safe to take this medication with all your current medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial to avoid potential interactions between this medication and other substances.
* Any existing health problems you have, as they may affect the safety and efficacy of this medication.
To ensure your safety, it is vital to verify that it is safe to take this medication with all your current medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
To minimize the risk of severe side effects, do not exceed the dosage prescribed by your doctor. Taking more than the recommended amount can increase your chance of experiencing severe side effects. Additionally, do not take this medication for a longer duration than specified by your doctor.
Until you understand how this medication affects you, avoid operating a vehicle, performing tasks that require alertness, or engaging in activities that demand your full attention. It is also recommended to avoid consuming alcohol while taking this medication.
Before using marijuana, other forms of cannabis, or prescription and over-the-counter (OTC) medications that may cause drowsiness or slow your reactions, consult with your doctor.
If you are considering giving this medication to a child, it is crucial to discuss the appropriateness of the medication with your doctor, as different brands may be suitable for different age groups. When administering this medication to a child, exercise caution, as children may be at a higher risk of experiencing excitability. This medication should not be used as a sleep aid for children; instead, consult with your doctor to explore alternative solutions.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor. It is necessary to discuss the potential benefits and risks of taking this medication to ensure the well-being of both you and your baby.
To minimize the risk of severe side effects, do not exceed the dosage prescribed by your doctor. Taking more than the recommended amount can increase your chance of experiencing severe side effects. Additionally, do not take this medication for a longer duration than specified by your doctor.
Until you understand how this medication affects you, avoid operating a vehicle, performing tasks that require alertness, or engaging in activities that demand your full attention. It is also recommended to avoid consuming alcohol while taking this medication.
Before using marijuana, other forms of cannabis, or prescription and over-the-counter (OTC) medications that may cause drowsiness or slow your reactions, consult with your doctor.
If you are considering giving this medication to a child, it is crucial to discuss the appropriateness of the medication with your doctor, as different brands may be suitable for different age groups. When administering this medication to a child, exercise caution, as children may be at a higher risk of experiencing excitability. This medication should not be used as a sleep aid for children; instead, consult with your doctor to explore alternative solutions.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor. It is necessary to discuss the potential benefits and risks of taking this medication to ensure the well-being of both you and your baby.
Overdose Information
Overdose Symptoms:
- Severe drowsiness or sedation
- Dilated pupils
- Flushed skin
- Fever
- Dry mouth
- Urinary retention
- Agitation, hallucinations, confusion
- Seizures
- Coma
- Respiratory depression
- Cardiovascular collapse
What to Do:
Seek immediate medical attention or call 911. For poison control, call 1-800-222-1222.
Drug Interactions
Contraindicated Interactions
- Monoamine Oxidase Inhibitors (MAOIs) (concurrent use or within 14 days of MAOI therapy)
Major Interactions
Moderate Interactions
- Potassium chloride (wax-matrix formulations - increased risk of GI lesions)
- Betahistine (pharmacodynamic antagonism)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Patient history (e.g., pre-existing conditions like glaucoma, prostatic hypertrophy, asthma, cardiovascular disease)
Rationale: To identify contraindications or conditions where anticholinergic effects could worsen symptoms.
Timing: Prior to initiation
Routine Monitoring
Symptom relief (e.g., sneezing, rhinorrhea, itching)
Frequency: Daily, as needed
Target: Reduction or resolution of allergic symptoms
Action Threshold: Lack of efficacy after appropriate trial, or worsening symptoms
Adverse effects (e.g., sedation, dry mouth, urinary retention, blurred vision, dizziness)
Frequency: Daily, as needed
Target: Absence or tolerability of side effects
Action Threshold: Intolerable side effects requiring dose adjustment or discontinuation
Symptom Monitoring
- Allergic symptom relief (sneezing, runny nose, itchy eyes/nose/throat)
- Sedation/drowsiness
- Dry mouth/nose/throat
- Blurred vision
- Urinary retention
- Constipation
- Dizziness
- Paradoxical excitation (restlessness, nervousness, insomnia)
Special Patient Groups
Pregnancy
Generally considered Pregnancy Category B. Use with caution, especially in the third trimester due to potential for adverse effects in the neonate (e.g., irritability, tremors, respiratory distress) if used close to delivery. Consult a healthcare provider.
Trimester-Specific Risks:
First Trimester:
Low risk, generally considered safe for occasional use.
Second Trimester:
Low risk, generally considered safe for occasional use.
Third Trimester:
Potential for adverse effects in neonate (e.g., irritability, tremors, respiratory distress) if used close to delivery. Avoid if possible.
Lactation
L3 (Moderately Safe). Can cause drowsiness/sedation in the infant and may decrease milk supply, especially with prolonged use or high doses. Use with caution; observe infant for drowsiness or irritability. Consider alternative non-sedating antihistamines if possible.
Infant Risk:
Moderate risk of sedation/irritability; low risk of decreased milk supply.
Pediatric Use
Not recommended for children under 12 years for the 12mg extended-release formulation due to risk of overdose and potential for paradoxical excitation (hyperactivity, restlessness) in younger children. For children 6-12 years, lower dose immediate-release formulations or other antihistamines may be considered under medical supervision.
Geriatric Use
Increased susceptibility to anticholinergic side effects (e.g., sedation, dizziness, confusion, dry mouth, urinary retention, constipation). Use with caution, start with lower doses, and monitor closely. Avoid in elderly patients with narrow-angle glaucoma, prostatic hypertrophy, or significant cognitive impairment.
Clinical Information
Clinical Pearls
- Chlorpheniramine is a first-generation antihistamine known for its significant sedative and anticholinergic side effects. Patients should be warned about impaired ability to drive or operate machinery.
- Extended-release formulations help reduce dosing frequency but do not eliminate side effects.
- Avoid concurrent use with alcohol or other CNS depressants due to additive sedative effects.
- Caution in patients with narrow-angle glaucoma, prostatic hypertrophy, bladder neck obstruction, or stenosing peptic ulcer due to anticholinergic effects.
- Paradoxical excitation (restlessness, nervousness, insomnia) can occur, especially in children and occasionally in adults.
Alternative Therapies
- Second-generation antihistamines (e.g., loratadine, fexofenadine, cetirizine - generally less sedating)
- Other first-generation antihistamines (e.g., diphenhydramine, brompheniramine)
- Intranasal corticosteroids (for allergic rhinitis)
- Nasal saline rinses
Cost & Coverage
Average Cost:
$10-30 per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist. If you have any questions or concerns about this medication, don't hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide detailed information about the overdose, including the medication taken, the amount, and the time it occurred.