Lidocaine for mouth and throat

Generic Name: Lidocaine (topical use in oral and pharyngeal mucosa)
Drug Class: Amide-type local anesthetic
Pharmacological Class: Sodium channel blocker

ATC Code: A01AD02 (for oromucosal use)

Common Brand Names
– Viscous Lidocaine (e.g., Xylocaine Viscous 2%)
– Lidocaine lozenges or sprays (e.g., Strepsils Max, Tantum Verde Lidocaine)
– Lidocaine + Antiseptic combinations (e.g., Difflam Plus, Cepacol Ultra)

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Mechanism of Action

Lidocaine exerts its anesthetic effect by reversibly blocking voltage-gated sodium channels in the neuronal membranes of oral and pharyngeal tissues. This:

• Inhibits nerve signal transmission

• Results in temporary localized numbness

• Reduces pain, burning, and irritation in the mouth or throat

Its onset is rapid due to the rich vascular supply in the mucosa, and effects are typically short-lived (15–60 minutes depending on form).

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Therapeutic Indications

Lidocaine is indicated for local oromucosal and pharyngeal anesthesia, including relief from:

1. Painful oral lesions:

   • Aphthous ulcers (canker sores)

   • Mucositis (e.g., chemotherapy/radiotherapy-induced)

   • Denture irritation or trauma

   • Herpetic lesions (adjunct only)

2. Pharyngitis and sore throat:

   • Relief of pain or irritation due to viral or bacterial causes

   • Used in combination with antiseptics or anti-inflammatories

3. Dental or medical procedures:

   • Pre-anesthesia for dental injections

   • Before dental impressions

   • To suppress gag reflex for endoscopy or throat swabs

4. Laryngoscopy or Intubation (prescription use):

   • Topical lidocaine sprays to numb the throat and reduce discomfort or cough

5. Pediatric use (restricted):

   • Oral pain due to teething (rarely used due to safety concerns)

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Formulations and Strengths

• Lidocaine Viscous Oral Solution (Rx):

  • Typically 2% w/v (20 mg/mL)

  • Used as a mouth rinse or gel-like application

• Lozenges/Sprays (OTC/Rx):

  • Lidocaine 1.5–3 mg per lozenge

  • Lidocaine sprays 5–10% (prescription strength)

  • Many contain combinations with chlorhexidine, cetylpyridinium, benzalkonium, or anti-inflammatories like benzydamine

• Gels (Topical for oral mucosa):

  • Lidocaine 5% oral gel (for mucosal ulcerations or wounds)

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Dosage and Administration

Lidocaine Viscous Oral Solution (2%):

• Adults: 5–10 mL swished in the mouth, held and gargled for 30 seconds, then expectorated (or swallowed if directed)

• Frequency: Every 3–4 hours as needed, not exceeding 4–6 doses per day

• Children (>3 years): Adjusted by weight; often ≤5 mL per dose

• Avoid eating or drinking for at least 1 hour post-application to avoid choking or aspiration

Lozenges and Sprays:

• Lozenges: 1 every 2–3 hours; maximum 6–8/day depending on brand

• Sprays: 1–2 sprays directed at throat; maximum 8–12 sprays/day

Pediatric Use Caution:

• Avoid in children <3 years due to choking and risk of methemoglobinemia

• Dosing should be prescribed by a pediatrician

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Pharmacokinetics (Mucosal Use)

• Absorption: Rapid from oral mucosa; increased with inflamed or abraded tissue

• Onset of action: 30 seconds to 5 minutes

• Duration: 15–45 minutes (shorter with saliva dilution)

• Metabolism: Hepatic (CYP1A2, CYP3A4)

• Excretion: Renal (as inactive metabolites)

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Contraindications

• Hypersensitivity to lidocaine or other amide-type local anesthetics

• Severe hepatic impairment (impaired metabolism)

• Ingestion in young children or patients with swallowing difficulties (risk of aspiration)

• Presence of severely infected or ulcerated oral tissues (increased absorption risk)

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Warnings and Precautions

1. Swallowing/Numbing Risk:

   • Lidocaine may numb the tongue, gums, and pharynx, impairing swallowing reflex

   • Increases choking and aspiration risk if used before meals or in children

2. Systemic Toxicity (overdose):

   • Especially from viscous solutions when swallowed in large volumes

   • CNS symptoms: agitation, seizures, drowsiness

   • Cardiovascular: bradycardia, hypotension, arrhythmias

3. Methemoglobinemia:

   • Rare but serious; most commonly in infants or with concurrent oxidizing agents (e.g., benzocaine, nitrates)

4. Repeated Use Caution:

   • Prolonged use may delay healing, especially in ulcerative conditions

   • Not recommended for chronic sore throat without evaluation

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Adverse Effects

Common (≥1%):

• Local numbness

• Altered taste

• Mild burning or stinging

• Sore or dry mouth

• Tingling of lips or tongue

Less Common:

• Nausea or vomiting (if swallowed)

• Swelling or erythema of oral mucosa

• Allergic rash

Rare/Severe:

• Anaphylaxis (very rare)

• Methemoglobinemia

• Seizures, CNS depression (with overdose)

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Drug Interactions

• Beta-blockers, cimetidine: May reduce lidocaine clearance at high doses

• Class I antiarrhythmics (e.g., mexiletine): Potentiated effects

• CYP3A4 inhibitors: May increase systemic levels (relevant in chronic or large applications)

• Other local anesthetics (e.g., benzocaine): Additive toxicity risk

• Nitrates, sulfonamides, or dapsone: May increase risk of methemoglobinemia

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Use in Pregnancy and Lactation

Pregnancy:

• Category B (US FDA): No teratogenicity observed; safe for short-term topical use on oral mucosa if needed

Lactation:

• Lidocaine is excreted in breast milk in low levels

• Short-term topical use is considered compatible with breastfeeding

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Overdose and Toxicity

Symptoms of lidocaine toxicity:

• Early: numb tongue, metallic taste, agitation

• Advanced: seizures, confusion, cardiac arrhythmias, hypotension

• Methemoglobinemia signs: cyanosis, headache, dyspnea, low oxygen saturation unresponsive to O₂

Treatment:

• Supportive care

• IV benzodiazepines for seizures

• Methylene blue for methemoglobinemia

• Activated charcoal (if ingestion is recent and toxic amount suspected)

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Patient Counseling Points

• Swish or apply only the amount recommended

• Do not eat or drink for 30–60 minutes after use

• Avoid repeated application without medical advice

• Do not use in infants, small children, or those with swallowing difficulty

• Store lidocaine viscous out of reach of children

• Do not use more than 6–8 lozenges or 8–12 sprays per day

• Seek immediate care if:

  • Breathing becomes difficult

  • Lips or skin turn blue

  • Numbness lasts unusually long

  • Swelling, rash, or irritation worsens

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Comparison with Alternatives

Product	Active Agent	Action
Lidocaine	Numbs pain fast	Short-acting local anesthetic
Benzydamine	NSAID + mild anesthetic	Anti-inflammatory & analgesic
Benzocaine	Ester anesthetic	Similar to lidocaine but higher risk of methemoglobinemia
Chlorhexidine	Antiseptic only	No pain relief
Cetylpyridinium	Antibacterial	Mild relief; often combined

Lidocaine provides more potent and targeted anesthesia compared to most OTC sore throat remedies.

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Storage and Handling

• Store at room temperature (15–30°C / 59–86°F)

• Protect from freezing and direct sunlight

• Keep out of reach of children

• Do not use past expiration date

• Discard if solution shows discoloration or odor changes