Are Cold Sores Genetic? Know How Your Genes Might Affect Them

Cold sores are an annoyance that many of us experience repeatedly. They are itchy and painful, not to mention a little unsightly, and sometimes seem to show up almost at random.

Is there a genetic component to who is prone to them? It’s possible, but there are also other things going on.

What are cold sores?

Cold sores are small blisters that form around or on the lips or, more rarely, elsewhere on the face. They are caused by the Herpes simplex virus, which stays in your system for life once you are infected and can come back periodically.

Cold sore blisters start as mildly itchy spots and then become pustulent blisters. They usually clear up within ten days, often faster.

What causes cold sores?

The Herpes simplex virus¹ causes cold sores. You are typically exposed to it as an infant or young child, and once you are exposed, the virus will stay in your skin for the rest of your life.

Most cold sores are caused by HSV type 1. However, cold sores are sometimes caused by HSV type 2, which causes genital herpes. 

In this case, you generally catch it by giving unprotected oral sex to somebody infected with HSV-2, often unknowingly. You should always use a condom or dental dam if you have oral sex with multiple partners or strangers.

The virus causes cold sores at intervals, usually when something stresses your immune system. Some people mistakenly think common colds or low temperatures cause cold sores. 

However, outbreaks can be triggered by another viral infection (while your immune system deals with the invader, Herpes simplex flares up), stress, sunlight, an injury to the affected area, or hormonal changes.

Many people are infected with Herpes simplex and never get a cold sore.

Are cold sores genetic?

Cold sores are not hereditary in the typical sense. Cold sores are not a genetic condition. 

However, genes appear to be linked to whether and how often you get cold sores once infected with Herpes simplex.

Can they be passed from mother to newborn?

It is possible to pass the Herpes simplex virus on to your child. HSV-2, which infects the genitals, can also infect the newborn, typically during birth but occasionally in-utero. 

You may also have HSV-1 in your genitals, which happens when you receive unprotected oral sex from somebody infected with HSV-1. This is rare as it is not a suitable environment for the survival of the virus.

Birth-acquired (congenital) herpes can be serious and is associated with breathing difficulties, lethargy, seizures, jaundice, and bleeding in the newborn. It can result in a coma. Systemic herpes can lead to encephalitis, which results in poor outcomes.

It is possible to infect a newborn with Herpes simplex by kissing them or cradling their face against your mouth.

Pregnant people with genital herpes may be given antivirals to reduce the risk of transmission. If you have an active outbreak close to your delivery time, your doctor may recommend a cesarean section.

If you have an outbreak of cold sores, avoid touching newborn infants if you can, and if you have to (such as if it’s your child), wear a surgical mask.

Are genes linked to frequent cold sores?

Cold sores are a contagious disease. However, there is growing evidence that there may be a genetic component to one’s susceptibility to having symptoms. 

Most Herpes simplex infections are asymptomatic, so whether one experiences cold sores and how often can depend on a variety of environmental and, yes, genetic factors. For example, you are more likely to get cold sores if you menstruate due to hormonal changes.

What does the research say?

Research has identified a gene called Cold Sore Susceptibility Gene-1² (CSSG-1), which appears to affect vulnerability to frequent cold sores. Certain haplotypes (sets of genetic determinants located on a single chromosome) of this gene are associated with more frequent and severe episodes.

This may result in cold sore susceptibility running in families. It’s not the disease that’s being inherited but an immune system variation that makes it harder for your immune system to get rid of the cold sores.

Another study³ showed a link between cold sore frequency and 2 SNPs (single nucleotide polymorphism, which are types of genetic variation among people),  within the C21orf91 region on chromosome 21. This study also homed in on the same candidate gene.

Essentially, a particular haplotype of CSSG-1 will make you much more likely to get cold sores if infected with Herpes simplex. Given that the virus is so common and so many of us carry it, it has the functional effect of making cold sores genetic.

Genetic factors may also explain why some people get one outbreak and never see another or why they stop getting them after a few outbreaks as their immune system learns to recognize it.

Affected populations

While no specific studies have been done, the gene appears more common among Caucasians. The study also demonstrated that women also have more outbreaks; this could be related to the association of outbreaks with menstruation.

However, the study population was also predominantly white, so there may be an impact on numbers here. More extensive studies need to be done to establish whether people of European origin are at higher risk of getting frequent cold sores.

Continued studies are planned to establish why the gene variant increases your risk of frequent cold sores. This might lead to new medication to reduce the incidence and severity of outbreaks.

How are cold sores diagnosed?

Many people with cold sores don’t bother going to the doctor, especially if it is not their first outbreak. Cold sores are self-limiting and considered minor. People typically only seek medical attention if the sores are particularly annoying or have lasted more than ten days, which may be an indication that it is not, in fact, a cold sore.

If you do see a doctor, they can typically diagnose it as a cold sore by visual examination. If there is any suspicion that it is more serious, they may take a swab to test for the presence of HSV-1 or HSV-2. 

You might also ask for this test if there is a chance that the infection may be HSV-2 (for example, if you had oral sex with a new partner recently), as different antivirals are used to treat them.

What are treatment options for cold sores?

Your doctor may prescribe an antiviral medication, which can shorten the duration of the cold sores and help them go away faster.

Many people do not need medication for cold sores, but you may want it if the infection is severe, if you are in a profession where unsightly blisters are an issue, or if you are caring for a newborn. 

Pregnant people are typically given antivirals, as are those with eczema and those with a weakened immune system due to HIV, cancer, or medication. Antivirals may be taken by mouth or applied directly to the sore as a cream, depending on its location.

Your doctor might also prescribe a lidocaine cream to be applied to the sores to relieve pain.

Over-the-counter medication

Pharmacies sell over-the-counter cold sore creams, which can also ease symptoms and potentially shorten the course of the outbreak. Your doctor may recommend one of these treatments, and if you have frequent cold sores, you can keep them handy. (Your doctor may also prescribe a cream to use more frequently if you have a lot of outbreaks.)

Over-the-counter pain relief gels applied to the cold sore can also help, and you can take an over-the-counter painkiller, ideally ibuprofen or acetaminophen.

Natural remedies

Some natural remedies appear to help treat the symptoms of cold sores. Some that actually work include:

• Placing ice on the sore or sucking on ice chips to help reduce the pain, burning, or itch

• Avoiding acidic food such as tomatoes and citrus fruits

• Avoiding salty and spicy food

• Placing a clean, cold, wet towel on the sores a few times a day

• Using petroleum jelly, which helps keep the skin around the sore from cracking

Of these, ice is generally considered the best remedy for easing symptoms quickly and with no side effects.

How to prevent cold sores

The best way to prevent cold sores is to avoid being infected with Herpes simplex. Unfortunately, it’s a widespread and contagious virus, but some ways to protect yourself include:

• Not having unprotected oral sex with strangers, new partners, or multiple partners

• Not sharing sex toys, which can spread genital herpes

• Not sharing towels, toothbrushes, razors, and other things that touch the face of others

• Not kissing or having sex with somebody who has a cold sore (long-term intimate partners are often infected with the same strain anyway, but it’s still best to be careful)

• Washing your hands before eating, touching your lips and eyes, and before or after sex and masturbation

If you have cold sores, avoid intimate contact with anyone. Wear a surgical mask if you must be physically close to another person, especially an infant.

The lowdown

As a viral infection, cold sores are not technically genetic. However, not everyone infected with Herpes simplex gets cold sores, and not everyone who gets them gets them as often as others.

Genetics appear to play a role in susceptibility to frequent cold sores, and studies are now being done to establish why and to help in developing medications.

In the meantime, you should talk to your doctor about cold sores, especially if you are immunocompromised, as they can give you antiviral medication to help. Remember to be vigilant about preventative measures against the spread of herpes.