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COMPOUNDS / SLEEP / CHLORPHENIRAMINE
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CHLORPHENIRAMINE

LOW RISK
BEST FOR:Allergy Relief●●●●●●●●○○8/10
CHLORPHENIRAMINE · CHLORPHENAMINE · CHLORPHENIRAMINE MALEATE · CHLOR-TRIMETON · PIRITON · CPM · ALLER-CHLOR
AntihistamineAllergyFirst-generationSedatingOTCAlkylamine

First-generation alkylamine antihistamine used for allergy relief; causes sedation via H1 blockade and anticholinergic activity.

ROUTE / DOSAGE
LOW2mg
STANDARD4mg
HIGH8-12mg
Note: Every 4-6 hours; max 24mg/day. Sustained-release forms 8-12mg every 8-12 hours.
CYCLE
Every 4-6 hours as needed max 24mg/day oral
BIOAVAILABILITY
~25-50% oral (significant first-pass metabolism)
ACTIVE DURATION
4-8h (subjective)
STORAGE
Room temperature dry away from light protect from moisture
HALF-LIFE
~20 hours (plasma)
DURATION BREAKDOWN
Total4-8 hours
Onset15-60 min
Come up30-60 min
Peak2-6 hours
Offset2-4 hours
After effects4-12 hours
Duration varies by route, dose, and individual. Source: community reports.
§ 01 — EFFECTS
6 documented
Allergy symptom relief
Sedation and drowsiness
Anticholinergic effects (dry mouth, blurred vision)
Reduced nasal congestion
Mild analgesia (preclinical)
Sleep promotion
§ 02 — RISKS
Rhabdomyolysis and acute kidney injury in massive overdose
Thrombocytopenia (rare, drug-dependent)
Agranulocytosis (rare)
CNS depression and anticholinergic toxicity in overdose
Sedation impairing driving and cognitive tasks
Paradoxical excitation in children and elderly
§ 03 — INTERACTIONS
Interaction data not yet available for this compound.
§ 04 — SCIENCE

Chlorpheniramine has been used clinically since the 1950s as an effective antihistamine for allergic rhinitis and urticaria. Its serum half-life is approximately 20 hours in adults, longer than previously reported, with wide interindividual pharmacokinetic variation influenced by age, renal function, and urinary pH. Preclinical studies in rats demonstrate dose-dependent cutaneous analgesic effects comparable to local anesthetics, suggesting potential peripheral analgesic utility. Overdose can produce severe CNS symptoms, and a case report documents rhabdomyolysis and acute kidney injury at 4000 mg ingestion. Rare hematologic adverse effects including thrombocytopenia and agranulocytosis have been reported. Evidence for off-label uses beyond allergy is limited.

§ 06 — SOURCES
[1]
Clinical pharmacokinetics of chlorpheniramine
pubmed.ncbi.nlm.nih.gov ↗
[2]
Chlorpheniramine poisoning as a potential cause of rhabdomyolysis
pubmed.ncbi.nlm.nih.gov ↗
[3]
Chlorpheniramine-dependent thrombocytopenia
pubmed.ncbi.nlm.nih.gov ↗
[4]
Hydrocodone/chlorpheniramine (Vituz)
pubmed.ncbi.nlm.nih.gov ↗
[5]
Chlorpheniramine produces cutaneous analgesia in rats
pubmed.ncbi.nlm.nih.gov ↗
[6]
Chlorpheniramine and agranulocytosis
pubmed.ncbi.nlm.nih.gov ↗
Disclaimer. Protokol.wiki is an informational reference. Nothing on this site is medical advice. Compounds listed may be unapproved, unregulated, or illegal in your jurisdiction. Consult a licensed physician before use. Data compiled from peer-reviewed literature.
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