Benzocaine
Place in Therapy
- Place in Therapy
Benzocaine is approved by Health Canada as a topical anesthetic that provides temporary relief of pain and itching associated with cold sores(1,2). There are minimal primary literatures that have been studied on the efficacy and safety of benzocaine. There’s one retrospective study that has compared 10% docosonal cream and 7.5% benzocaine for the treatment of herpes labialis and demonstrated similar efficacy for faster healing and shorter duration of discomfort (3). However, there are many limitations to the internal and external validity of the study. There is also not much evidence from other literatures to support shorter duration of lesions and reduction of eruptions. Similar to other local anesthetics, such as tetracaine, lidocaine, and pramoxine, the use of benzocaine as a temporary pain reliever for people who have mild discomfort from cold sores is consistent among other tertiary literatures (4). Common products usually contain 5-20%, but there is not much data though that compares the efficacy with the different concentrations of benzocaine. Because benzocaine is a 4-aminobenzoic acid ethyl ester, products with the ester structure are shown to cause significant sensitization then other local anesthetics with an amide or nonester/nonamide structure (2,5). It may also cause allergic contact dermatitis if symptoms get worse. As a result, it has suggested to be only used once every few hours (4).
Bottom Line: There’s no evidence to support benzocaine as a treatment option for cold sores, but evidence does prove its use as a temporary symptom reliever for pain and itching. However, benzocaine is more likely to cause sensitization than other topical anesthetics. Therefore, it is considered as one of the last resorts as compared to other anesthetics, especially with patients who have a history of allergy to local anesthetics.
References
1. Benzocaine monograph. Heath Canada: Drug and Health Products. Available from: http://webprod.hc-sc.gc.ca/nhpid-bdipsn/atReq.do?atid=oral.hcp&lang=eng. Last updated on March 24, 2014. Accessed July 19, 2014.
2. Conklin JS. Chapter 92: Cold Sores. In: Patient Self-Care – helping your patient make therapeutic choices. 2nd ed. Ottawa, ON: Canadian Pharmacists Association; 2010:489-493.
3. Mccarthy JP, Browning WD, Teerlink C, Veit G. Treatment of Herpes Labialis: comparison of two OTC drugs and untreated controls. J Esthet Restor Dent. 2012:24(2):103-109.
4. Urban MA. Herpes simplex virus infections. The Merck Manual Home Health Handbook: for patients and caregivers. Available from: http://www.merckmanuals.com/home/infections/viral_infections/herpes_simplex_virus_infections.html. Last updated on November 2009. Accessed June 25, 2014.