Topical anaesthetics are among the most useful and underutilised OTC products in pharmacy. Whether you’re preparing for a blood test, managing painful skin conditions, or dealing with a mouth ulcer, local numbness can transform a painful experience into a manageable one.

How Topical Anaesthetics Work

Local anaesthetics block sodium channels in peripheral nerve cell membranes. By preventing sodium from flowing into the nerve cell, they block the propagation of the electrical action potential that conveys pain signals to the brain. When applied to skin or mucous membranes, they block sensory (pain) nerve fibres before they reach systemic circulation — providing numbness in the area of application without affecting consciousness. The depth of penetration and duration of effect depend on: the specific compound (lidocaine vs tetracaine), the formulation (cream, gel, spray, patch), the anatomical site (mucous membranes absorb faster than intact skin), and whether the area is occluded.

Common Uses

Venepuncture and injections — EMLA cream (lidocaine 2.5% + prilocaine 2.5%) is the standard topical anaesthetic for pre-procedure skin numbing. Apply under occlusive dressing 60 minutes before needle insertion. Effective for children and needle-phobic adults. Genital procedures — lidocaine gel is widely used for urinary catheterisation and minor gynaecological procedures. Mouth and throat — benzocaine gel (Bonjela) for mouth ulcers; lidocaine (Difflam Plus, Chloraseptic spray) for sore throat. Anal fissure and haemorrhoids — lidocaine preparations in combination products (Anusol Plus, Anoheal) provide pain relief for defecation. Sunburn and insect bites — lidocaine spray or gel provides rapid, effective relief from burning and itching.

Safety Considerations

Topical anaesthetics are very safe when used as directed but several cautions apply. Don’t apply to broken skin (increased systemic absorption). Avoid extensive application over large body surface areas (particularly relevant to EMLA in young children — age and weight-based dose limits apply). Benzocaine can very rarely cause methaemoglobinaemia (particularly in infants — use lidocaine-based products instead). Allergic reactions to local anaesthetics do occur but are rare — typically to ester class (benzocaine, tetracaine) rather than amide class (lidocaine, prilocaine).

Browse First Aid and Topical Anaesthetics at Huncoat Pharmacy. Related: Wound Care Guide.

At Huncoat Pharmacy: Browse topical anaesthetic products, Private prescription service.