benzocaine: clinical use

Prescribing considerations

• Confirm that symptoms match the licensed indication; oral benzocaine may mask a condition requiring medical or dental treatment.
• Persistent or severe oral pain, systemic symptoms or an unresolved ulcer requires assessment rather than continued symptomatic treatment.
• Review concurrent sulphonamide treatment and allergy history before recommending a product.

Contraindications and cautions

• Hypersensitivity to benzocaine or any formulation ingredient.
• Known or suspected impaired conversion of methaemoglobin to haemoglobin, including a family history of methaemoglobinaemia.
• Selected products are contraindicated below 12 years of age.

Monitoring

• Investigate grey or blue mucosa or skin, unusual breathing or breathlessness urgently as possible methaemoglobinaemia.
• Assess local burning, rash, oedema or dermatitis for hypersensitivity or excipient-related reactions.

Clinical pharmacology

Benzocaine is an ester local anaesthetic that reversibly inhibits neuronal membrane depolarisation and ion exchange. It is absorbed through mucous membranes and damaged tissue, then hydrolysed mainly by plasma esterases and to a lesser extent in the liver.

Formulation and product differences

• Orajel Mouth Gel is licensed for mouth-ulcer and denture-related pain. It contains propylene glycol and sorbic acid, which may cause local reactions.
• Orajel Extra Strength is licensed for toothache involving an open carious lesion and exposed vital pulp. It contains sorbic acid and has a different flavour and excipient profile.