Cold Sore Causes

What Triggers the Cold Sore Virus?

Cold sores can be triggered by a host of internal and external factors. Although many triggers are recognized by the medical community, others are little understood.

Living in a dormant state, herpes simplex virus (HSV-1) is in a constant battle with your healthy and functional immune system. However, whenever your immune system is weakened, even for a short period of time, an outbreak can occur.

Fever blisters can also be awakened by trauma to your mouth and lips. Any action that can stimulate the specific nerve channel that leads from the dormant virus to your mouth/lips can awaken this viral skin condition.

Although worrying about the situation is not the answer, it is wise to be aware of the known triggers. Understanding the triggers and adopting preventative measures can substantially decrease the likelihood of a fever blister recurrence.

Let’s take a close look at HSV-1 and how you can manage known triggers while also protecting others from the viral transmission.

Why Do Cold Sores Keep Coming Back?

When you have HSV-1 in your system, you’ll be affected for the remainder of your life. The virus will usually be inactive. Unfortunately, it can be activated by localized factors (injury, sunlight, etc.) and systemic factors (immune weakness, stress, menstruation, etc.)

Cold sores come back because a viral flare-up can occur at any time. There is no sure-fire way to know when this will happen, but there are some definite warning signs that you MUST heed.

You’re likely to notice specific patterns. For example, you may develop fever blisters more often when you’re under stress at work and getting less sleep. Recognizing and avoiding the factors that trigger cold sores is essential, but there is no fool-proof way of staying protected. You’ll need a treatment plan!

Although an outbreak is at best unpredictable, the early symptoms are easily identifiable. By knowing the signs, you can begin treatment during the prodrome (tingle) stage. This will deliver the fastest results.

The sooner that you take action, the quicker that you’ll heal and fully recover. Cold sores keep coming back because HSV-1 always resides in your body and internal/external factor are triggering it. Find out what’s affecting you!

Final takeaways…

  • There is currently no cure for HSV-1. This is why cold sores return after your primary (first) outbreak. Some people are affected more than others.
  • The virus can be activated at any time. While specific triggers are usually behind the problem, some flare-ups happen without any explanation.
  • Learn to recognize the earliest symptoms and always be proactive.

Why Do Cold Sores Appear in the Same Place?

When you’re infected with HSV-1, the virus occupies a nerve bundle area near the ear. This is known as the trigeminal ganglion.

The virus will remain dormant in these nerve cells until it’s activated. Once triggered, it will follow a nerve path to the surface of your skin.

This path is typically the same path that viral transfer initially took place. For example, if HSV-1 entered the center portion of your bottom lip, it will likely occur at the same location each time.

The virus will awaken, travel down the trigeminal ganglion, and then begin the cold sore life cycle. While HSV-1 does move along a distinct nerve channel, it is possible for an outbreak to occur in other areas of the face.

Blisters can form on the chin, cheek, nose, fingers (hepatic whitlow) and space just outside of the lip border. These areas can become infected due to viral spreading.

Important points of note…

  • Once you are infected by HSV-1, the virus will occupy territory within a nerve chain (the trigeminal ganglion).
  • The virus will awaken, travel through the cell chain, and reach the surface. Where it ends up is usually where your original viral transmission occurred.
  • While fever blisters can develop in other areas near the original location, they tend to occur in the same spot because it’s the original path.

What Are Cold Sore Triggers?

Cold sore triggers can be broadly defined as aggravators and irritants. Anything that can awaken the herpes virus, both internally and externally, falls broadly under this umbrella.

Although many triggers are universally recognized by the medical community, some remain unknown and poorly understood. That is why fever blisters can occur at any time. However, you will likely be more vulnerable to certain triggers than you are to others.

Many risk factors can lead to initial cold sore transmission and recurrence. They include behavioral decisions and pre-existing health concerns. These range from oral sex to illness/sickness.

Risk factors can be defined as legitimate concerns based on a ‘likely’ cause. Although the likelihood of cold sores rises steeply when one of these factors comes into play, it doesn’t mean that the virus will definitely be activated. They are just warning signs that need to be understood.

Let’s take an in-depth look at the known triggers.

Immune Weakness

HSV-1 preys on poor immune health, thus ‘immune weakness’ is a cold sore trigger.

Any ailment that impacts your immune system can lead to recurrent cold sores. Multiple battles against illness and infection at the same time leave you far more vulnerable to herpes simplex one.

  • Important: The severity of the illness/disease/treatment will influence how adversely you’ll be affected. For example, chemotherapy to remove cancer cells can be particularly aggressive and can leave you immunocompromised.

Some people get multiple cold sores, one after the other. Your line of defense has been severely compromised when your immune system is fighting several battles at the same time or lacks the weaponry to fight off the virus effectively.

When the virus remains inactive, it is primarily due to having a robust immune system. Your body is in a strong position to fight off the virus. You can potentially go for months (or even years) without getting cold sores.

What are the possible cold sore triggers?


Chronic stress and anxiety can impact your mental and emotional well-being. These triggers can affect your mood, thus creating additional tension.

The result is stress that manifests itself as a physical trigger. Just being on edge constantly can sometimes awaken the herpes virus because the body produces more cortisol and this has implications for your thyroid glands.

The frantic pace of your emotions can increase your blood pressure and affect your state of wellness. These symptoms, in many respects, are not all that different from a sickness.

If stress can be powerful enough to cause gray hair, baldness, and sleepless nights it can be a trigger for cold sores. Getting your stress and anxiety under control is crucial to staying healthy and keeping cold sores away.

  • Tip: The introduction of meditation, yoga, and stress-free recreational activities can positively assist you. A walk around town after a demanding day at work can be beneficial for your body, calm your mind, and reduce negativity. Talking about how you feel can provide a source of relief.


Fatigue means tiredness, lethargy, and weakness. This downgrades your immune system. Your body needs the energy to function optimally.

Fatigue, whether a chronic problem or due to a short-term lack of sleep, can prevent your immune system from doing its job at peak efficiency. Most people need 6- 8 hours of uninterrupted sleep per night. Any less than the nightly minimum and your body won’t function nearly as well.

  • Important: A condition known as Chronic Fatigue Syndrome (CFA) can also be a problem. CFA is the by-product of a faulty immune system. It’s caused by a “malfunctioning immune system” that results in perpetual fatigue. The inability to manage and remove illness is common.

Hormonal Changes

Hormonal changes can awaken herpes simplex one. Menstruation and pregnancy are two dramatic hormonal shifts. These fluctuations naturally heighten your emotions and leave your body feeling drained. During menstruation, a woman’s moods and emotions can range from anxiety to anger.

Hormonal swings escalate once again in the weeks prior to birth. While natural changes in the body are the obvious cause, fear, worry, and stress can also create emotional swings.

When hormonal changes can be intense, the result is virtually the equivalent to a physical illness. What your immune system has to endure during these times can be very demanding. This game of “hormonal ping pong” can easily awaken HSV-1 and lead to fever blisters.

Extensive Dental Work

Many people get cold sores after a dental visit or hygienist appointment.

Dental work can cause trauma to the lips and mouth area. Lip dryness and cracking, due to holding the mouth wide open for a prolonged period of time, can cause skin damage.

Getting a filling or a bridge won’t trigger a cold sore outbreak, but any damage caused to the skin by a drill or sharp medical instrument has the potential to activate the virus.

  • Important: These fluid-filled lesions are extremely infectious. Most dentists WON’T perform work during the weeping stages. It’s more likely to spread the infection, and treatment will be more painful.

Dentists may still perform emergency dental work, though. They’ll typically request that you place a patch over the cold sore to keep everyone safe. Each practice has its own rules, so you do need to give your dental practice a call before your appointment.

Inform your dentist that you’re prone to cold sores. You’ll typically find that your dentist will take extra care not to over-stretch your lips and cause damage.

Why do I keep getting cold sores?

Tobacco Use

You may find that tobacco products awaken HSV-1. This includes both cigarettes as well as smokeless tobacco. Because nicotine is an immune suppressor, the introduction of smoking can be harmful.

The use of smokeless tobacco (including vaping) not only introduces nicotine but it also physically manipulates the lips. The stretching of the lip to form a “dip pocket” can irritate the surface of your lip and result in cracking.

If you develop a cold sore, all tobacco use should be halted until complete healing has been achieved. It could introduce further complications if tobacco particles were to enter during the ulceration stage.

Food and Beverage Choices

The consumption of foods and beverages that are high in arginine, highly processed, acidic, and spicy should be avoided or significantly reduced. This includes chocolate, peanuts, walnuts, citrus fruits, fruit juice, beer, and sodas.

Consuming a healthy diet that is rich in lysine can be beneficial, according to some (but not all) experts. Vegetables, dairy milk, cheese, fish, and poultry are quality sources of lysine. You can also take a supplement if you don’t like many of these types of food.

Be mindful of your intake of certain foods and drinks. Moderation is the key. Cold sores are more likely to form if you make a habit of over-indulging on certain dietary substances. Take note of how your body responds.

Extreme Weather and Artificial Heat

Weather conditions and artificial indoor heating can dry and chap your lips. This is why keeping a protective lip balm on your person is very important.

While there are ways to avoid harsh climates and drastic temperatures changes, but many times you’ll find that applying a chapstick to your lips most beneficial.

  • Hot weather and intense exposure to the sun can burn your lips. Similar to sunburn on your arms and face, your lips can also be damaged by ultraviolet (UV) rays.
  • Cold weather and wind can harm your lips. Introducing chapping, dryness, and windburn, cold weather and freezing winds can be as brutal as sunny conditions. Applying a protective lip balm is once again the best way to navigate harsh winter conditions.
  • Indoor heaters and tanning beds can cause problems. Indoor heat can dry out your lips and trigger cold sores.

Lip Wounds

Direct lip trauma, accidental or otherwise, can trigger a cold sore outbreak. Actions, such as lip biting and face shaving, can awaken herpes simplex one from its dormant state.

While biting and nervous rubbing are more than likely habitual, cutting and shaving are usually due to an accident. Maneuvering a razor blade too close to your lips can result in nicks and abrasions.

Protecting your lips goes far beyond applying a protective moisturizer. It is crucial to avoid wounding your lips and mouth area.

Are Cold Sores Contagious?

Cold sores are contagious from the tingle stage right up until the time that the site has FULLY healed. This encompasses the entire lifecycle.

Contrary to popular belief, the virus is active during the scabbing stage. HSV-1 is extremely contagious, but not quite as infectious as earlier in the lifecycle due to the reduced number of virions present at the site of the cold sore.

While it may look like a ‘regular’ blister, it is home to a highly contagious virus. Shield your family, friends, and partner from the viral transmission, particularly pregnant women and babies. It can cause babies a great deal of harm!

The American Academy of Dermatology provides the following suggestions:

  • Avoid kissing
  • No mouth-to-genital contact (oral sex)
  • Stay away from people with a weakened immune system due to illness. For example, a family member who currently has the flu virus.
  • Don’t share your drinks, utensils, lip balms, razors, lipsticks, etc. with other people.
  • Do not touch your sores as this can lead to viral spreading. You could spread HSV-1 to other areas of the face or infect other individuals.
  • Wash your hands immediately after applying treatment. Remain hygiene-conscious.

Can Cold Sores Be Spread by Kissing?

Kissing is a common way that HSV-1 is spread. Primarily transferred by kissing during the tingle stage (before the appearance of a blister), contaminated saliva is the culprit.

  • According to Johns Hopkins Medicine, 50-80% of adults have herpes simplex one.
  • The National Institute of Health believes that 9 out of every ten adults will be exposed to HSV-1 by the time they turn 50 years of age.

While those statistics are shocking, they reveal the truth about the severity of this virus. Kissing is one of the causes of cold sores.

If you notice a tingling feeling on the lips, you should start treatment without delay. The longer that you delay, the more time it will take for the cold sore to completely heal.

Best Cold Sore Treatments

Take a look at some top rated cold sore treatments below.

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Mederma Cold Sore Discreet Healing Patch - A Patch That Protects and conceals Cold Sores - 15 Count
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Mederma Cold Sore Discreet Healing Patch - A Patch That Protects and conceals Cold Sores - 15 Count
  • FAST HEALING ultra-thin Hydrocolloid Gel provides a moist environment to help: relieve pain, reduce the blistering and prevent scabbing.
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Campho Phenique Cold Sore and Fever Blister Treatment for Lips, Maximum Strength Provides Instant Relief, Helps Prevent Infection To Promote Healing, Original Gel Formula, 0.23 Oz
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Campho Phenique Cold Sore and Fever Blister Treatment for Lips, Maximum Strength Provides Instant Relief, Helps Prevent Infection To Promote Healing, Original Gel Formula, 0.23 Oz
  • Specially formulated for cold sores/fever blisters
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  • Store at room temperature