Topical Acyclovir for Cold Sores: Dosage and Treatment Protocol
Topical acyclovir is substantially less effective than oral antiviral medications for cold sores (herpes labialis) and its use is generally discouraged. 1
Efficacy of Topical Acyclovir
- Topical acyclovir cream provides only modest benefits for cold sores, with clinical trials showing a reduction in healing time of approximately 0.5-0.6 days compared to vehicle control 2
- When used, topical acyclovir must be applied very early in the course of an outbreak (ideally during the prodromal stage) to achieve even limited effectiveness 3, 2
- The limited efficacy of topical formulations is primarily due to inadequate penetration of the drug into the basal epidermis, which is the target site of infection 4
Recommended Protocol (If Used Despite Limitations)
- Apply 5% acyclovir cream 5 times daily for 4 days 2
- Begin application as soon as possible after onset of symptoms, preferably within 1 hour of noticing prodromal symptoms (tingling, burning) 2
- Continue application for the full treatment course even if symptoms begin to resolve 3
- Apply to the entire area identified as affected, not just visible lesions 3
Superior Alternatives
- Oral antiviral medications are significantly more effective than topical formulations for treating cold sores 1, 5
- Recommended oral options include:
Important Considerations and Limitations
- Topical acyclovir does not prevent the development of classical lesions (progression to vesicles, ulcers, and crusts) 2
- Neither topical nor oral acyclovir eradicates latent virus or affects subsequent risk, frequency, or severity of recurrences 1, 6
- Patients with frequent recurrences (six or more episodes per year) should consider oral suppressive therapy rather than episodic topical treatment 1, 5
- Combination products containing acyclovir and hydrocortisone (e.g., Xerese) have not shown significant benefits over acyclovir alone 7
Special Populations
- For immunocompromised patients, oral or even intravenous antiviral therapy is preferred over topical treatment due to the risk of more severe and prolonged episodes 1
- HIV-infected patients may require more aggressive therapy than topical treatment can provide 1, 6
- Pregnant women should discuss the risks and benefits with their healthcare provider, as the safety of topical acyclovir during pregnancy has not been fully established 6