Key takeaways:
~ Cold sores are caused by the herpes simplex virus (HSV).
~ Less than half of people with HSV will get cold sores from the virus.
~ Genetics plays a role in who will get cold sores, and environmental factors can trigger the occurence.
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What causes cold sores?
There are two types of herpes simplex virus: HSV-1 and HSV-2. Cold sores are usually caused by HSV-1, while genital herpes is usually caused by HSV-2. But, it’s possible for either type of HSV to cause either condition.
Once the herpes simplex virus enters your body, it stays for life. It hides in nerve cells and can become active again later, causing another outbreak of cold sores.
Cold sores are highly contagious and can be easily spread through close contact, such as kissing or sharing utensils. If you have a cold sore, it’s important to avoid close contact with others, especially newborns, and to wash your hands frequently to prevent spreading the virus.
Using DNA from people who lived in the Bronze Age, researchers now think that HSV-1 has been making the rounds in humans for around 5,000 years. [ref]
Science of cold sores
Cold sores are also called herpes simplex labialis or fever blisters.
About 60%-80% of the population is seropositive for HSV1, but only around 20%-30% of the population will ever get cold sores. Some people get a cold sore rarely (once or twice a decade), while others may have monthly outbreaks.[ref][ref]
The sores that form on the outside or inside of the lip are uncomfortable — and embarrasing for some people. Who wants an open sore or big scab on their lip…
Typically, cold sores form when the HSV virus is actively replicating. Often people with notice tingling or burning in the affected area before the development of the sore. Rupturing of the blister that forms will lead to a scab. [ref]
Why does this happen? The virus infects nerves around the mouth and remains latent in the nucleus of neurons, undetected by your immune system. When reactivated, the virus creates new infectious particles that move down the neuron to the skin, causing the sores.
Interestingly, the latent virus is thought to enhance the survival of the infected cells.
What causes the reactivation of the virus?
Triggers of HSV reactivation include: [ref]
- stress, which can alter immune response
- ultraviolet (UV) radiation (sunburn)
- temperature fluctuations (cold, wind, heat)
- surgical trauma or dental procedures
- immunotherapy that suppresses the immune response
- hormonal changes
Researchers find that HSV-1 reactivates in the trigeminal nerve when the immune system is suppressed such as during times of stress or when fighting off another infection.
Why doesn’t everyone with HSV get cold sores?
This is a question that researchers have been trying to answer for decades.
Genetics is at least part of the answer as to why everyone doesn’t get cold sores. The strain of the herpes simplex virus may play a role as well. Additionally, an external stressor such as wind, sunburn, or oral surgery may need to be involved for some to activate the virus.[ref][ref]
Keep in mind that not every gets the herpes simplex virus. Transmission of the virus is usually through skin contact and is more likely if there is slight damage to the surface of the skin.[ref] Additionally, genetic variants in the immune response genes may protect some individuals from ever getting the virus.[ref]
Cold Sores Genotype Report
Variants related to development and neurons
POU5F1 gene: transcription factor key in embryonic development and stem cells
Check your data for rs885950 (23andMe v5):
- A/A: typical
- A/C: slightly increased risk of cold sores: [ref]
- C/C: increased ris of cold sores
Members: Your genotype for rs885950 is —.
C21orf91 gene: the function of this gene isn’t really understood yet, but it is thought to have something to do with neuron differentiation
Check your genetic data for rs10446073 (23andMe v4; AncestryDNA):
- G/G: increased likelihood of cold sores[ref]
- G/T: increased likelihood of cold sores; increased risk of herpetic eye disease[ref]
- T/T: typical risk
Members: Your genotype for rs10446073 is —.
Check your genetic data for rs1062202 (whole genomes, not in 23andMe):
- G/G: increased likelihood of cold sores[ref]
- A/G: increased likelihood of cold sores
- A/A: typical
Members: Your genotype for rs4360170 is —.
Variants related to immune response:
VDR gene: vitamin D receptor
Check your genetic data for rs2228570 FokI (23andMe v4):
- G/G: typical
- A/G: increased risk of cold sores
- A/A: increased risk of cold sores[ref]
Members: Your genotype for rs2228570 is —.
IL1A gene: encodes interleukin 1A, and inflammatory cytokine.
Check your genetic data for rs1304037 (AncestryDNA):
- C/C: reduced chance of recurrent cold sores
- C/T: increased chance of recurrent cold sores
- T/T: increased chance of recurrent cold sores (common genotype)[ref]
Members: Your genotype for rs1304037 is —.
HCP5 gene: human endogenous retrovirus, variants relate to response to AIDS and the immune system
Check your genetic data for rs4360170 (whole genome, not in 23andme or AncestryDNA):
- A/A: typical
- A/G: increased risk of cold sores
- G/G: increased risk of cold sores[ref]
Members: Your genotype for rs4360170 is —.
Lifehacks: Cold Sore Solutions
Talk with your doctor about the pros and cons of prescription-based antiviral medications for cold sores.
The rest of this article is for Genetic Lifehacks members only. Consider joining today to see the rest of this article.
Natural treatments for cold sores:
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