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Herpes simplex - oral - Management
Should I consider prescribing an oral antiviral to treat cold sores?

  • For immunocompetent individuals, oral antivirals are not routinely indicated for the treatment of cold sores but may be indicated in severe episodes. However, the optimum timing and dose of oral antiviral treatment are uncertain. Consider seeking specialist advice (particularly for pregnant women — unlicensed use).
  • Seek specialist advice for people who are immunocompromised (including people with HIV).
Clarification / Additional information
Basis for recommendation
  • These recommendations are based on published expert review, evidence from randomized controlled trials (RCTs) and feedback from expert reviewers.
  • CKS does not recommend that oral antivirals should be used in immunocompetent individuals for mild-to-moderate episodes given the self-limiting nature of the disease, the limited benefits of oral antivirals, and that treatment needs to be initiated at the onset of prodromal symptoms (before the appearance of lesions).
    • Most episodes of cold sores are generally mild and self limiting and can be treated symptomatically. For further information, see Self care advice.
    • Evidence from double-blind placebo-controlled RCTs involving immunocompetent individuals indicate that [Raborn et al, 1987; Spruance et al, 1990b; Spruance et al, 2003; Spruance et al, 2006]:
      • Treatment with oral antivirals (aciclovir, valaciclovir, and famciclovir) does not appear to have an impact on the development of lesions, number of participants developing lesion pain, or the proportion of people with aborted lesions.
      • Oral antivirals can reduce the duration of a cold sore episode by 1.0–1.5 days when taken very early (typically within 1 hour of the onset of prodromal symptoms and before the appearance of any signs of cold sore lesions). Aciclovir taken at the papular lesion stage was found to have no effect on the duration of the episode and pain.
      • A reduction of 1.0–1.5 days in the duration of pain and lesion healing was only seen with higher dosage regimens of oral antivirals.
    • Timing of treatment
      • As for topical antivirals, it is expected that the maximum clinical benefit from antiviral therapy is gained when treatment is started early because most viral replication occurs within the first 48 hours. Early initiation of antiviral therapy terminates virus replication and hence limits the subsequent epithelial damage responsible for the development of visible lesions [Esmann, 2001].
  • However, they may be of most use in severe cases or in immunocompromised individuals at risk of developing further complications [Spruance et al, 1990b; Arduino and Porter, 2006; BNF 54, 2007; Woo and Challacombe, 2007].
  • Specialist advice should be sought for systemic treatment of herpes simplex infection in pregnancy [BNF 54, 2007]. Oral antivirals are not licensed for use in pregnancy.
  • Seek specialist advice when considering oral antiviral therapy in children.
    • There are no trials involving oral antivirals in those under 18 years of age for the treatment of cold sores [Woo and Challacombe, 2007].

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