Dichlorobenzyl Alcohol: Antiseptic for Throat and Oral Infections / Articles

Introduction

Dichlorobenzyl alcohol (2,4-dichlorobenzyl alcohol, DCBA) is a chlorinated derivative of benzyl alcohol with pronounced antiseptic properties. The compound is widely known as the active ingredient in over-the-counter throat lozenges such as Strepsils, Neo-Angin, Lorsept, and Gorpils. Due to its dual mechanism of action — antimicrobial and local anesthetic — dichlorobenzyl alcohol is effective in treating throat and oral infections caused by both bacteria and viruses. The compound also finds use as a preservative and antimicrobial component in cosmetic and hygiene products.

Chemical Structure and Physicochemical Properties

Dichlorobenzyl alcohol is an aromatic compound with the molecular formula C₇H₆Cl₂O and a molecular weight of 177.02 g/mol. The most common and pharmacologically active isomer is 2,4-dichlorobenzyl alcohol (CAS 1777-82-8), in which two chlorine atoms are located at positions 2 and 4 of the benzene ring.

Key physicochemical parameters:

CAS Number: 1777-82-8
Molecular formula: C₇H₆Cl₂O
Molecular weight: 177.03 g/mol
Melting point: 55–58 °C
Solubility: approximately 1 g/L in water
SMILES: OCC1=CC=C(Cl)C=C1Cl
UNII: 1NKX3648J9

The presence of two chlorine atoms on the benzene ring significantly increases the lipophilicity of the molecule, facilitating its penetration through microbial cell membranes and enhancing antimicrobial activity. The compound contains no chiral centers and is optically inactive.

Mechanism of Action

Dichlorobenzyl alcohol exerts its therapeutic effects through two complementary mechanisms.

Antimicrobial Action. The primary mechanism involves disruption of microbial cell membrane integrity. Dichlorobenzyl alcohol interacts with lipids in cell membranes, causing destabilization, which leads to cell dehydration and protein coagulation. This chaotropic membrane action provides a broad spectrum of activity against Gram-positive and Gram-negative bacteria, as well as fungi. No reduction in efficacy is observed with prolonged use.

A key feature is the activity of dichlorobenzyl alcohol against respiratory viruses. Studies show that lozenges containing dichlorobenzyl alcohol in combination with amylmetacresol have direct virucidal effects against respiratory syncytial virus (RSV), influenza A virus, and SARS-CoV coronavirus.

Local Anesthetic Action. In addition to its antimicrobial effect, dichlorobenzyl alcohol provides rapid relief of sore throat pain through reversible blockade of voltage-gated sodium channels (Nav) in sensory neurons. This mechanism is similar to that of local anesthetics such as lidocaine and ensures rapid onset of analgesic effect.

Pharmacokinetics and Metabolism

Dichlorobenzyl alcohol is rapidly absorbed from mucous membranes and rapidly eliminated from the body. Metabolism occurs with the formation of 2,4-dichlorobenzoic acid, which is excreted by the kidneys either in free form or as a glycine conjugate.

The compound is characterized by low absorption from mucous membranes, ensuring primarily local action with minimal systemic exposure. At therapeutic doses (1.2 mg per lozenge), systemic absorption is minimal.

Clinical Applications

Throat and Oral Infections. Dichlorobenzyl alcohol is a key component of many over-the-counter lozenges for the treatment of acute pharyngitis, tonsillopharyngitis, and other inflammatory throat conditions. In a clinical study, lozenges with amylmetacresol and 2,4-dichlorobenzyl alcohol (Strepsils) demonstrated rapid analgesic effects lasting up to 2 hours. Combination with lidocaine provides additional pain relief.

Studies show that preoperative use of lozenges containing dichlorobenzyl alcohol reduces the incidence of postoperative sore throat and cough.

Dentistry. Dichlorobenzyl alcohol shows activity against 115 strains of dental plaque microorganisms, with highest efficacy against Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis — pathogens associated with aggressive forms of periodontitis. A dentifrice containing 0.3 % dichlorobenzyl alcohol maintains antimicrobial activity for 5–10 minutes after brushing.

Cosmetic and Pharmaceutical Industries. Dichlorobenzyl alcohol is used as a preservative and antimicrobial component in cosmetic products (creams, lotions, shampoos) at concentrations up to 0.5 %. It is also used as a preservative in pharmaceutical preparations to inhibit bacterial and fungal growth.

Safety and Toxicology

Dichlorobenzyl alcohol is characterized by low acute systemic toxicity. In animal studies, the oral LD₅₀ is 2,300 mg/kg in mice and 3,000 mg/kg in rats.

In a prenatal developmental toxicity study in rats, adverse effects were observed only at a dose of 800 mg/kg/day, significantly higher than human therapeutic doses. The NOAEL (no-observed-adverse-effect level) was determined to be 400 mg/kg/day for both maternal and prenatal development.

With topical use, dichlorobenzyl alcohol may cause irritation of mucous membranes. Rare cases of allergic contact dermatitis have been reported. The compound is classified as having low risk for carcinogenicity, allergenicity, and reproductive toxicity.

Storage and Handling

Dichlorobenzyl alcohol should be stored in tightly sealed containers in a dry, cool place protected from light. The melting point of 55–58 °C indicates the need to avoid heating above this temperature. When handling the compound, personal protective equipment is recommended: gloves and safety goggles. In case of skin or mucous membrane contact, rinse thoroughly with water.

Conclusion

Dichlorobenzyl alcohol (2,4-dichlorobenzyl alcohol, CAS 1777-82-8) is an effective and safe antiseptic agent with broad-spectrum antibacterial and antiviral activity. Its unique dual mechanism — direct antimicrobial action on microbial cell membranes and local anesthetic effect through sodium channel blockade — provides rapid symptom relief in throat and oral infections. Its use in lozenges, oral hygiene products, and cosmetics is supported by extensive clinical experience and scientific research. The favorable safety profile and minimal systemic absorption make dichlorobenzyl alcohol the agent of choice for topical antiseptic therapy in adults and children over 6 years of age.