Can You Be Immune To Cold Sores?

Overview

Also referred to as fever blisters, cold sores are tiny blisters that break open to form ulcers. They usually form around the mouth or on the lips. In some cases, they may appear on other parts of the face, such as under the nose.

Cold sores are caused by a virus known as the herpes simplex virus (HSV). They can be spread through close skin-to-skin contact, kissing, or sharing personal items like towels and utensils with a person who has an active sore.

There is no known cure for cold sores. After a person is infected, the virus lies dormant within the body for lengthy periods. It may later come back and cause cold sores again. According to the NHS, a typical outbreak of cold sores will clear within 7–10 days without treatment.¹

At the same time, some people are asymptomatic, which means they don't develop symptoms. This often raises the question — can you be immune to cold sores?

This guide will look at all you need to know about cold sores and how best to protect yourself from getting them.

What causes cold sores?

Cold sores are caused by the herpes simplex virus (HSV). It's important to note that there are two types of herpes. Cold sores are almost always caused by herpes simplex type 1 (HSV-1), while the other type of virus, herpes simplex type 2 (HSV-2), usually causes genital herpes. 

In rare cases, cold sores may be caused by HSV-2. Oral infection with HSV-2 usually occurs through having oral sex with a person with genital herpes.

According to the American Academy of Dermatology Association (AAD), cold sores are very contagious. Many children acquire the HSV-1 virus when they are young. This may occur through being kissed by a person with a cold sore or sharing utensils and towels with people with cold sores.²

This is why you are advised to refrain from kissing or sharing utensils with a person with a cold sore until the cold sore heals completely. In some cases, the virus that causes cold sores can be spread even when the person doesn’t have any visible cold sores. However, it’s most likely to spread during an active outbreak.

Symptoms

Symptoms of cold sores affect each individual differently. Some people don't experience any symptoms with their first attack. Others experience the formation of sores (ulcers) around or inside the mouth, which may be accompanied by flu-like symptoms.

The most common symptoms include:

• A tingling sensation on the lips, commonly experienced before the cold sores appear

• Small blisters on the mouth and lips, which later burst and crust over

• Itchy or dry sensation around the lips and mouth

• Feeling sore around the lips and mouth

Some other symptoms you might experience during an outbreak include:

• Fever

• Swollen lymph nodes

• Muscle aches

If you're infected with the herpes simplex virus for the first time, the cold sore might not appear until 20 days from the first exposure.

These symptoms usually go away on their own after about 7–10 days. However, you should call your doctor if you develop any symptoms affecting the eye during a cold-sore outbreak. Left untreated, an outbreak of herpes simplex virus in the eye can lead to vision loss. This is a rare but serious complication of HSV infection.

How long are cold sores contagious?

The HSV-1 virus is highly contagious and can be spread even when a person has no visible symptoms. However, it's most contagious when cold sores are present. The virus remains contagious until the sores completely disappear, which takes about two weeks.

You should wait until any cold sores have healed completely before kissing someone or sharing utensils or drinking glasses with them.

How does it spread?

The HSV-1 virus, which causes cold sores, is spread through close contact with the saliva or skin of an infected person or by sharing personal towels and utensils. The virus will enter the body through breaks in the skin, which may even be too small to notice.

Once you contract HSV-1, you'll have it for life. There is currently no vaccine for the virus nor natural immunity to it. The virus lies dormant inside your nerve cells and can periodically reactivate. Some people may go for many years without experiencing an active outbreak, which may lead them to believe that they've developed immunity. However, there is no scientific evidence to back this claim.

At the same time, someone with HSV-1 is still at risk of getting infected with HSV-2.

What can increase the likelihood of cold sore outbreaks?

According to the AAD, more than half of Americans between the ages of 14 and 49 carry the herpes simplex virus. Some infected people never get cold sores at all, while others get cold sores early on but then develop antibodies and never get another cold sore.

Still, others experience repeated outbreaks of cold sores throughout their lives, although outbreaks tend to occur less frequently after age 35.

Risk factors

You are most at risk of getting a cold sore or HSV-1 infection when you come into physical contact with the fluid of a cold sore. This can be done through the following:

• Kissing an infected person

• Sharing utensils or drinking glasses with an infected person

• Sharing towels or personal items (like toothbrushes) with an infected person

Triggers

Cold sore outbreaks occur when the dormant virus is triggered to reactivate. Although it’s not always obvious why this has happened, some factors commonly trigger the virus to reactivate. These include:

• Fatigue

• Stress

• Illness, like a cold, flu, or fever

• Injury to the affected area (where you’ve previously had a cold sore)

• Strong sunlight

• Dental work

• A weakened immune system

• Laser treatment or cosmetic surgery

• Certain foods

• Hormonal changes, like getting your period

Common myths about cold sores

There are some myths about cold sores we need to debunk so that you can better protect yourself and your loved ones. Here are the most common of them.

Once you get a cold sore, you're immune for life

While some people with HSV-1 rarely experience outbreaks, there is no immunity or cure for cold sores. Like other herpes types, the body will start an immune response once infected. This might make the outbreaks less severe over time or make you asymptomatic.

However, being asymptomatic doesn't mean you are immune to HSV-1. Even if it’s been a long time since you’ve had an outbreak, this doesn't completely rule out the possibility of a future outbreak.

Cold sores only appear when you have a cold or during cold weather

Many different triggers can cause cold sores. Cold weather or being infected with a cold virus are two of them. It’s true that your immune system, which usually keeps the virus from forming blisters, tends to weaken when fighting off a cold, which can trigger an outbreak of cold sores. 

Drastic temperature shifts, such as extreme cold or heat, can also trigger outbreaks. However, there are many other potential triggers.

How are cold sores diagnosed?

Doctors usually diagnose a cold sore by examining the sore itself. If the initial diagnosis is not conclusive, the doctor may take a sample of the cells by swabbing the sore and then testing for the presence of the herpes simplex virus.

Complications of cold sores

After the initial infection, you might experience more severe symptoms. This is because your body has not yet developed any immunity to the virus. It is rare to experience complications, but they can happen.

This is most common in small children or people with health conditions that weaken the immune system, such as AIDS or cancer.

Call a doctor if you experience any of the following symptoms:

• Difficulty breathing or swallowing

• High/persistent fever

• Irritated or red eyes, with or without discharge

How are cold sores treated?

There is currently no cure for cold sores, but there are ways to treat and manage them when they appear. Some medications that may be used include:

• Antiviral ointments and creams (such as penciclovir and acyclovir)

• Antiviral oral medications (like acyclovir, valacyclovir, and famciclovir)

• Over-the-counter anti-inflammatory agents or topical anesthetics

When they first appear, cold sores can take up to three weeks to fully heal. However, recurring outbreaks will typically heal in about a week, even if no medicine is used.

The antiviral medications work most effectively when applied 3–4 days before the blister forms (ideally when you start feeling a tingly sensation on your lips). They can decrease the severity and duration of an outbreak.

Anti-inflammatory medications and topical anesthetics don’t directly address the virus itself. They don’t shorten the outbreak, but they can help to keep you more comfortable while your body is healing.

Can cold sores be prevented?

If you haven't experienced a cold sore before, try to avoid skin-to-skin contact or sharing items like utensils with a person who has a visible cold sore. This will decrease your chances of becoming infected with the HSV-1 virus. 

If you've had a cold sore before, then you already have this virus in your body. You can decrease the frequency of outbreaks by finding out your triggers and avoiding them.

If you are using a medication, starting treatment is best as soon as you feel a tingling and burning sensation in the area before the sore even develops. This will reduce the healing time of the cold sore.

At the same time, you can also prevent spreading the virus by avoiding skin-to-skin contact with others (such as kissing), or sharing personal items like lip balms and food utensils, while you’re having an outbreak.

The lowdown

In a nutshell, cold sores are small blisters that usually form around the lips and are caused by the herpes simplex virus 1. There is currently no cure or vaccine for the virus, which means you can't be immune to cold sores.

However, some people are asymptomatic and might never experience any symptoms or cold sores, even though they’re infected with the virus. And for those who experience them, the symptoms tend to become more manageable as your body builds up an immune response over time, with outbreaks becoming less frequent as a person ages.