Cold Sores

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 area^1B,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.

Cold sores spread from person to person through direct contact with an infected area i.e oral-to-oral contact like kissing or sharing utensils or towels^1E,3D. Cold sores last 10 to 14 days and are often very severe, making eating and drinking extremely uncomfortable ^1F.

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.

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.

Stages of cold sores

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}.

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

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:

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 form^1M.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

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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