Cold Sores
Cold Sores
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What are cold sores?
Cold sores are caused by a virus called Herpes Simplex Virus (HSV) 1A. The virus enters the body through a crack or damage in the skin thereafter it remains dormant inside the body in the collection of nerve cells (ganglia) near the spinal cord that supply the nerve fibres to the infected area1B,C. Although most people aren’t exactly sure when they first encountered the virus, it’s usually contracted in early childhood 3A,4A. Periodically the virus will reactivate when ‘triggered’ causing the virus to travel through the nerve fibres back to the skin to cause eruptions of blisters in the same site of infections 1D,3B.
Cold sores are highly contagious, affecting 64% of people worldwide (estimated 3.5 billion people) under 50 years old 1E,2A. Oral HSV-1 recurs up to 6 times a year 3C.
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Types of Herpes Simplex Virus
There are 2 strains of this virus; HSV-1 and HSV-2. The main differentiator of the two herpes simplex viruses is their location or where they appear 1A,G,2B.
- Herpes Simplex 1 (HSV-1) is usually associated with sores on the lips (Herpes labialis) 1A,G,2B.
- Herpes Simplex 2 (HSV-2) is associated with sores on the genitals and is almost entirely sexually transmitted 1A,G,2B.
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Primary vs Recurrent infections
Primary Infection: The initial cold sore infection can appear 2 to 20 days after contact with the virus 3E. The first infection may be very painful with symptoms of painful sores inside the mouth, tender enlarged lymph nodes, fatigue, fever and feeling generally ill 1H,3F,4B,7A. This can lead to poor oral intake and dehydration 3G. After the primary infection, the virus lies dormant in the body but can reactivate to cause symptoms 3I. Recurrent infections: Oral HSV-1 recurs up to 6 times a year 3C. Cold sores can affect appearance and impact quality of life 3H. Recurrent infections are unlikely to be clusters 1J. The duration of the symptoms tend to be shorter with symptoms being less severe 3I.
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Stages of cold sores
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Cold sore triggers
The herpes simplex virus (HSV-1) is the cause of the infection however the infection can be reactivated by triggers such as psychological and environmental factors 1A,L,3K. Triggers of cold sore outbreaks vary from person to person. It’s important to identify what your cold sore triggers are, so you can manage them to help avoid developing a cold sore. Here are some of the more common cold sore triggers 1L,3K,5A,6A,B,7B. 
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Risk factors
People who have weakened immune systems are at higher risk of complications from the virus. Medical conditions and treatments that increase your risk of complications include 7C:
- HIV/AIDS
- Severe burns
- Eczema
- Cancer chemotherapy
- Anti-rejection drugs for organ transplants
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Tips to prevent the spread of cold sores
Tips to avoid the spread of cold sores to other people or to other parts of your body, you might try some of the following precautions 7D: 
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Treatment
There is no current cure for cold sores however antiviral medications are used to treat cold sores 1M. Treatment is most effective if started early, when the lips start to tingle, burn or become itchy, before the blisters form1M. Commonly used antiviral medications are acyclovir or penciclovir 1M. Acyclovir is an antiviral medication that is active against Herpes Simplex Virus type 1 and type 2 and can be used for both primary and recurrent infections 8A,B. Antiviral creams like Acyclovir provide the below key benefits to cold sore patients: 
- Prevents the virus from replicating 8C
- Reduce the severity of symptoms 9A
- Therapy should be initiated as soon as possible following the onset of signs and symptoms of herpes simplex infection 8D
- Treatment should be continued for 5 days. If healing has not occurred, the treatment may be prolonged for up to 10 days 8D
Medical References
- Pringle, C. R. Merck Manual. Merk Manual (Merck Sharp & Dohme Corp., 2018). doi:10.1001/ archsurg.1972.04180110125043
- James, C., et al. Herpes simplex virus: Global infection prevalence and incidence estimates, 2016. Bull. World Health Organ. 98, 315–329 (2020).
- Usatine, R. P. & Tinitigan, R. Nongenital herpes simplex virus. Am. Fam. Physician 82, 1075–1082 (2010).
- Saleh D., Yarrarapu SNS., Sharma S. Herpes Simplex Type 1. StatPearls Publishing (2020) doi: 10.5772/21902.
- Padgett, D. A., Sheridan, J. F., Dorne, J., Berntson, G. G., Candelora, J. & Glaser, R. Social stress and the reactivation of latent herpes simplex virus type 1. Proc. Natl. Acad. Sci. U. S. A. 95, 7231–7235 (1998).
- Schmidt, D. D., Zyzanski, S., Ellner, J., Kumar, M. L. & Arno, J. Stress as a precipitating factor in subjects with recurrent herpes labialis. J. Fam. Pract. 20, 359–366 (1985).
- Mayo Clinic. Cold sore [online] [cited 2018 November 28.]; Available from URL: https://www.mayoclinic.org/diseases-conditions/cold-sore/symptoms-causes/syc-20371017
- Acitop approved Professional Information, June 2003.
- InformedHealth.Org (Internet). How effective are creams and tablets for the treatment of cold sores. Institute for Quality and Efficiency in Health Care (IQWiG) 6-8 https://www.ncbi.nlm.nih.gov/books/NBK525789/ (2006).
- Based on internal analysis by iNova Pharmaceuticals (Pty) Ltd using data from the following source: IQVIA TPM MAT December 2024 ACT4 D6D1 Topical Antivirals. Brands are measured in Units, reflecting estimates of real-world activity. Copyright IQVIA.
ACITOP cream. Reg. No. 32/20.2.8/0719. 
Reg. No. 06/20.2.8/0099 (Namibia). Each gram of cream contains 50 mg of Acyclovir (5,0 % w/w Acyclovir). Marketed by: iNova Pharmaceuticals (Pty) Limited. Co. Reg. No. 1952/001640/07, 15E Riley Road, Bedfordview. Tel. No. 011 087 0000. www.inovapharma.co.za. For full prescribing information, refer to the approved Professional Information. For more information, speak to your healthcare professional. IN5054/25 Applicant: CIPLA MEDPRO (PTY) LTD Co. Reg. No. 1995/004 182/07. Building 9. Parc du Cap, Mispel Street, Bellville, 7530, RSA. Website: www.cipla.co.za Customer Care: 080 222 6662 
October 7, 2021
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