Are Cold Sores Supposed To Bleed?

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What are cold sores?

Cold sore is the common name for the reactivation of the herpes simplex virus on the vermilion border of the lip. There are two types of this virus, HSV-1 and HSV-2. HSV-1 mainly causes the cold sores that develop around your lips and mouth, while the HSV-2 virus mainly causes genital blisters, but both viruses can cause both sores. 

Don't be embarrassed if you have the herpes virus. The prevalence of HSV-1 in people aged 14–49 is almost 50%. Once you have the virus, it stays in your body forever, but as you get older, the cold sore outbreaks tend to diminish.¹

Are cold sores contagious?

Cold sores are highly contagious. The virus survives better in warm and moist environments, so skin-to-skin contact is the perfect breeding ground for transmission.

If you have a cold sore, you should tell anyone you've kissed recently or had close sexual and non-sexual intimate contact that you've had an outbreak, and limit your affectionate displays to hugs until the sore has completely healed.

How often do people get cold sores?

Everyone is different when it comes to their reaction to the herpes virus. About 28% of the population has an outbreak once a year. Some people get a cold sore almost immediately and have frequent recurrences, while others are completely asymptomatic and never show any signs of the disease — although they are still carriers.²

Who is affected by cold sores?

Since the herpes virus spreads so easily, anyone who comes into close contact with someone infected can catch the disease. Many people don't realize they can still spread the virus for a few days after the cold sore has healed or even asymptomatically in specific cases.

So if you kiss someone who's recently had an outbreak or share a drink or lip balm, they're still shedding the virus and can transmit it to others.

Symptoms and causes

There are two ways you can get a cold sore.

The first is when you are initially exposed to the virus — you'll usually get a primary HSV-1 infection a few days after exposure, usually in the context of gingivostomatitis, i.e., infection of the mouth and gums.

The second is when an outside factor triggers a recurrence — for example, you're already sick with something like the flu or a cold, and your immune system is weakened, you're under a lot of stress, your body is undergoing hormonal changes (you’re pregnant or on your period), or you’ve been exposed to UV light, e.g., used a tanning bed or suntanned.

Once you have had that first cold sore, it's easy to recognize the symptoms that one is developing under the skin. The first sign is a tightness and tenderness around your lips and mouth, with maybe a burning sensation. That's the virus replicating until it finally pops out in the form of tiny, weepy blisters.

Stages of a cold sore 

There is a defined life cycle to a cold sore — stages that play out on your face or genital area over two to three weeks, although it seems like much longer.


This is when the virus is dormant in your body. You won't have any symptoms and may even forget you have the HSV-1 virus. During the latent phase, no infectious virions are produced. It's possible that you are still shedding the virus, even though you don't have any symptoms. 


Tingling and tenderness are the warning signs that the virus is heading toward an outbreak. You'll feel itching, burning, tingling, a bit of swelling — or all of the above. The skin in the affected area may get a little red and rough, too. You can spread the virus at this stage.

Vesicular lesion

The tiny, fluid-filled bumps show up 6-48 hours after you notice the first signs of swelling or itching. There’s usually a single lesion, which can make eating, drinking, or even talking painful. Over-the-counter (OTC) painkillers can help here, and avoid salty or acidic foods to prevent more pain.


The blisters pop open after a day or two, and you have oozing fluid from the open sore. This is when you are most contagious.


Around the fifth day, a brownish crust over the sores is formed. This crust, while not very visually appealing, forms a scab that lets you know the sore is healing and the virus is being killed off. Like any scab, it will itch, and if you scratch it, it will bleed.


Complete healing takes several more days. As with any scab, this one will dry up, shrink, and fall off, leaving fresh new skin behind. This is the end stage of a cold sore's life cycle, and the virus goes back into hiding in your nerves until something triggers a recurrence.

Managing cold sores

You can slow the growth and severity of a cold sore by treating it before it develops. An OTC antiviral cream or a patch can help manage pain and start the healing process if you recognize the signs and start applying the medication several times a day or as directed. You should see your doctor regardless, especially if you have underlying conditions that can worsen it.

Prevention is key

The best way to ensure your cold sore doesn't bleed is to keep it moist and not pick at it when it itches. If the itching is unbearable, apply a topical ointment with a numbing agent, such as benzocaine or lidocaine, to the area. 

The lowdown 

When you have a cold sore, the best thing you can do to promote healing is to visit your physician to start oral antivirals as soon as possible. Popping the blisters simply makes it easier for the virus to spread, and picking at the scab has the same effect — only this can also cause scarring. Washing your hands really well after you've applied ointment or touched the blister will also keep the virus contained.

  1. Prevalence of herpes simplex virus type 1 and type 2 in persons aged 14–49: United States, 2015–2016 | Centers for Disease Control and Prevention

  2. Cold sores—an epidemiological survey (1976)

Other sources:

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