When your cold sore splits open, it is crucial to clean the area and treat it with an over-the-counter cold sore medication as soon as possible. Not uncommon, damage to the blister can be the byproduct of both internal and external factors.

Keeping your cold sore covered and moistened can eliminate splitting in most cases. Often caused by a lack of moisture, fever blisters are more susceptible to cracking and splitting once they become overly dry.

To avoid this situation, it is also essential to assess your surroundings. If your sore keeps splitting you could be subjecting yourself to a harsh environment. Intense winds, cold weather, extreme sun, stagnant air, and indoor heating can deplete your blister of much-needed moisture.

Let’s explore this topic in greater detail and examine the causes and what to do if you do run into a problem.

What Should You Do When Cold Sores Split?

When you have a cold sore lesion on your lips or corner of your mouth, it’s all too easy for it the blister or scab to split open (crack) prematurely. This can happen due to your own actions or through no fault of your own. Either way, the result will likely be the same!

When your cold sore cracks open, it’ll release a clear or whitish fluid (pus) containing the herpes virus (HSV-1). The liquid is highly contagious. If you get recurrent cold sores, you MUST be prepared so that you can prevent the virus from spreading to other parts of the face.

While it’s natural to react in haste when your skin has been damaged in some way, this should always be avoided. Just as it would be unwise to pick off a cold sore scab early, the same logic applies to an active fever blister. Remain patient and be proactive if any cracking does occur.

Here is a quick 3-step treatment guide regarding what to do…

1. Clean the Blister

  1. Using warm water, you need to clean any fluid, blood, and crusting.
  2. Dab the blister/scab with a fresh washcloth. Hold the cloth in position for several minutes to soak up any excess liquid. This is essential if your cold sore is bleeding.
  3. Make sure that the site of the cold sore has been cleaned before applying an OTC treatment or medicated numbing agent. Always wait for any bleeding to have stopped completely.

Use latex gloves when examining and cleaning your blister. This will reduce the likelihood of viral spreading and self-contamination.

2. Reduce Swelling

Once the area has been cleansed, you should apply ice to reduce swelling. This will also help to reduce any redness that has occurred.

  • Fact: In an interview with the University Of Pennsylvania Perelman School Of Medicine (AAD), Dr. Bruce A. Brod, who serves as a clinical professor of dermatology at the University of Pennsylvania Perelman School of Medicine, suggests the use of a cool, wet towel. Using this measure, multiple times a day for 5-10 minutes, can reduce redness and general irritation.

The cracking of a blister or scab is a form of facial trauma. It is really common for swelling to occur in and around the cold sore, so don’t be overly alarmed if/when this happens.

Before the healing process can recommence, any obvious signs of damage must be corrected. The prime objective is to return your fever blister (as close as possible) to the state it was in before harm occurred.

3. Numb the Pain

Using pain relievers, such as Ibuprofen or an alternative over-the-counter painkiller, you can significantly reduce the level of discomfort that you’re experiencing.

While blisters will burst naturally, any premature cracking is likely to be extremely painful. Stinging, burning, itching, and bleeding are highly likely.

How Do You Treat a Cracked Cold Sore?

The treatment of a cracked cold sore is no different from that of a routine blister/scab. Once the area has been cleaned, and any swelling and pain have been minimized, normal treatment can be reconvened.

OTC Medication

The use of products, such as Abreva and HERP-B-GONE, can be extremely beneficial. They’re affordable and easy to apply.

Designed to reduce the pain and speed up the healing time, OTC creams and ointments aim to seal up any cracking and reduce the chances of a bacterial infection.

Lip Balm

These will keep your blister moist and provide a thin layer of external protection.

You need to protect a cracked cold sore/scab from the elements. Lip balm, similar to a cream, allows your blister to heal with a reduced risk of experiencing problems due to external influences (germs, bacteria, etc.)


Although it has no active healing properties, Vaseline can seal a cracked sore, protect it from the elements, and supply some much-needed moisture.

Aloe Vera Gel

This natural ingredient has active healing properties that are perfect for a swollen cold sore.

Safe to apply Aloe Vera directly to the skin, aloe vera gel can have a cooling and soothing effect. It will help to numb the site of your blister until the crack has sufficiently sealed.


You should add moisture to your skin by increasing your intake of water.

Although blister/scab dryness is usually the by-product of external elements, the dryness can also be due to not drinking enough water each day. Increasing your water consumption is beneficial.

How Can You Prevent Cold Sore Cracking?

The best way to prevent cracking is to keep the blister/scab moist and free of debris.

While most cracking is the result of dry/windy environmental conditions or an absence of hydration, some splitting does arise from everyday incidents (or accidents).

Treat Outbreak during the Tingle Stage

The way to prevent a blister from cracking is applying your preferred treatment during the prodromal (tingle) stage. This is the warning sign that you’re about to get a cold sore.

By using the Virulite device, which uses light technology and is FDA-approved, you may be able to bypass the blister stage completely.

Achieving results in as little as 72 hours, the Virulite device is one of the best treatments on the market.

Keep Blister Moist

Because cracking is usually the result of excessive dryness, keeping your blister moist is of paramount importance. This is critical if you live in a hot or cold climate and are frequently outdoors.

Whether through an OTC cream, Vaseline, aloe vera gel, etc., keeping your blister covered and moistened can protect it while also promoting natural (and medicated) healing.

Use a Cold Sore Patch

The use of a cover-up, such as the Compeed invisible patch, can provide you with medicated relief, a moist cover, and a protective shield.

Invisible patches are perfect if you are often in a public setting and need to conceal your cold sore while also treating it so that it goes away faster.

Journal of the European Academy of Dermatology and Venereology published a randomized controlled trial which concluded the Compeed patch was a safe and effective alternative to prescription antiviral medications. Compeed’s immediate benefits in not only healing but general blister protection were noted.

Why Do Cold Sores Split?

Cold sores can split for a variety of reasons but most deal with external factors and behaviors. Unless you are using a patch to cover your blister or a thick cream, your sore is open to the elements.

Just like any other portion of your skin, the weather and your environment can be detrimental.

The key is to recognize problematic situations beforehand. Being able to avoid certain places and locations can save you a lot of grief.

Windy and Cold Weather

If your cold sore keeps breaking open, it could be due to weather conditions. Although windy and cold temperatures can trigger HSV-1, they can also damage existing fever blisters and scabs.

If you are dealing with a bleeding cold sore that has been caused by a crack, it could be the result of harsh elements. Both windy and cold weather conditions can dry out cold sores thus making the skin very brittle and flaky. Splitting and cracking is often the result.

  • Pro Tip: Cover your mouth with a scarf or another item of clothing if you are faced with intense cold and windy conditions. This can be a useful means of protection if your blister is not covered by a cream or patch at that moment.

My cold sore won't stop bleeding

Hot Weather

If your cold sore keeps cracking and bleeding, it could be the result of the sun. Prolonged exposure to the sun, most notably during the summer months, can harm active fever blisters.

In the same way that the sun can cause burns on various portions of your body, the sun can also be traumatic to fever blisters. Causing them to burst, crack, and split, hot weather can dramatically dry out cold sore and fever blister scabs.

  • Pro Tip: The use of a cold sore patch can be used as a buffer against the sun. Although patches are used to treat blisters and provide essential medication, they can also be used as a guard against the elements. Using a patch to shield against the sun can be invaluable.

Dry Air

Dry and stagnant air can strip your cold sore of necessary moisture. While not as obvious as harsh weather conditions such as wind and heat, dry air can cause splitting and cracking.

Not limited to outdoor conditions, dry air can be found in a variety of settings. This can include your home as well as other indoor public spaces.

Use a humidifier in your home to keep the air moist. This is an excellent way to prevent an active fever blister from drying out and splitting.

Indoor Heating

The use of indoor heating can be detrimental. Drying them out, indoor heating can cause cold sore scab bleeding and cracking.

Artificial heat is designed to warm an area, but it won’t improve the air quality. Pumping hot air into a room can diminish circulation. This can result in a cozy environment, but one that is void of fresh-flowing air.

  • Pro Tip: Apply aloe vera gel or Vaseline to your blister if you must endure harsh indoor heating.


If you are not taking in enough liquids, it can manifest in blister cracking and splitting. While keeping your blister moist from an external standpoint is vital, it is equally important to fuel your body.

Dehydration can negatively impact the natural healing process. If your livelihood or recreational activities involve physical activity, it is vital to stay hydrated. This will not only improve your general state of health, but it will also protect your cold sore.

do cold sores split open?

Accidental or Intentional Damage

If your cold sore won’t heal, it could be due to your own actions. While accidents do happen, intentional manipulation can cause a cold sore to split.

It’s common for young people to manipulate their blisters in an attempt to remedy the situation. Continually touching and picking at the site of a cold sore can cause it to split and burst prematurely.

Can Cold Sore Cracking Cause Infection?

If not properly treated, it is possible for a cracked cold sore to become infected.

This is why it is vital that your sore is cleaned and treated immediately. Leaving a split sore in its natural state can introduce debris and bacteria.

What Are the Signs of an Infected Cold Sore?

The primary signs of an infected cold sore are the pain, redness, swelling, and a slow natural healing process. Viral spreading and the appearance of further cold sores are also a possible symptom.

When Should You See a Doctor?

You should consult your primary care physician if the pain refuses to subside and the sore doesn’t heal. If your condition continues to worsen, it’s likely that something is wrong.

Most cold sores, even when split, will continue to heal naturally when treated with HERP-B-GONE. If it becomes damaged and produces more intense symptoms, you should seek medical attention.


  1. Karlsmark, T. , Goodman, J. , Drouault, Y. , Lufrano, L. , Pledger, G. Randomized clinical study comparing Compeed® cold sore patch to acyclovir cream 5% in the treatment of herpes simplex labialis. Journal of the European Academy of Dermatology and Venereology 2008; 22: 1184-1192. doi:10.1111/j.1468-3083.2008.02761.x