Daily Health

The Stages of a Cold Sore

Feeling a strange tingle around your mouth? Maybe you're noticing a slightly inflamed or itchy patch? If you've had cold sores before, you know exactly what that tingle means. If not, it's possible that you might be experiencing your first cold sore outbreak.


These breakouts aren't fun, but they're nothing to be embarrassed about. While no one looks forward to a cold sore outbreak, they're a lot more common than you might realize and typically aren't anything to get too worried about.

In fact, between 20% and 40% of adults experience cold sore outbreaks, while many others carry the virus responsible for cold sores asymptomatically without ever getting a cold sore.

What is a cold sore?

Cold sores, sometimes called fever blisters, are small, fluid-filled blisters that typically appear on the lips or around the mouth. Occasionally, they can appear on the chin, cheeks, inside nostrils, on gums, or on the roof of the mouth.  They follow a familiar cold sore timeline of five stages, and while they can be uncomfortable, they typically clear up within a week.

There isn't a cure for the virus that causes cold sores, but treatments are available that can speed up the healing process and ease pain or discomfort.

What causes cold sores?

Cold sores develop due to infection by a form of the herpes simplex virus, a common virus that many people carry without even knowing it. The version of the virus that typically causes cold sores, HSV 1, is distinct from the HSV 2 virus generally responsible for genital herpes.

It's worth noting that both HSV 1 and HSV 2 are transmissible during oral sex, so a small percentage of cold sore cases are the result of the HSV 2 virus. Similarly, it's possible for HSV 1 to cause genital herpes if the virus is transmitted to that area. However, HSV1 typically affects the mouth area, while HSV2 typically affects the genital area.

Just because someone has been infected with the herpes simplex virus at some point doesn't necessarily mean they'll experience cold sores. Many people with this virus never experience a cold sore in their lives, you may carry the virus for years without a breakout. It’s possible to carry the virus without ever knowing you have it or experiencing a breakout.  

How does a cold sore start?

Cold sore breakouts can be caused by a range of triggers. Some common ones include:

  • exposure to hot weather and sun exposure
  • strong wind
  • a weakened immune system
  • another viral infection, fever, or cold
  • hormonal fluctuations such as those associated with the menstrual cycle
  • stress
  • fatigue
  • injuries to the skin

As you can see, many of these triggers are common and unavoidable parts of life, making it difficult to prevent cold sores once the herpes simplex virus is present. However, it is possible to reduce the likelihood of breakouts with preventative oral treatment.

How are cold sores treated?

Since cold sores are caused by a virus, topical or oral antiviral medications are used to treat them. These medications limit the spread of the herpes simplex virus to other healthy cells, reducing the severity of a breakout. It is important to note that no medication can cure or eradicate the virus. 

A breakout can clear up on its own, but early treatment can shorten cold sore duration and severity. If you experience recurring cold sore breakouts, you may even want to consider taking cold sore medication preventatively.

Antiviral oral medications

Oral medications can help manage outbreaks of cold sores. Valtrex, also known by the generic name valacyclovir, is a prescription oral medication that can be taken at the earliest sign of a breakout. It takes effect quickly, and after two or three days typically provides some relief from a breakout.

The sooner you can start taking Valtrex or valacyclovir, the faster it will provide relief. If you experience several breakouts a year, taking valacyclovir preventatively is an option you can discuss with your healthcare practitioner.

Antiviral creams

Prescription creams can also be used in the treatment of cold sores. Just like oral medication, the sooner the cream can be applied after the symptoms of a cold sore breakout emerge, the quicker it can work. In Canada, a common prescription antiviral cream for cold sores is acyclovir.

If a cold sore breakout is painful, over-the-counter pain medications such as acetaminophen or ibuprofen may help to alleviate the discomfort. Avoiding acidic or spicy foods can also help prevent discomfort since these foods can further irritate the sore.

What do the cold sore stages look like?

There are five cold sore stages that a breakout will pass through. While breakouts can vary in size and number of blisters, they all go through these five stages without treatment, so you can use them to gauge how far along you are in a breakout.

Stage 1: Tingling

One of the first signs of an imminent cold sore blister is tingling around the lips. During this first stage, you may also experience some redness or slight inflammation, along with an itching or burning sensation. Soreness and swelling may also be experienced.

If you have cold sore medication on hand, taking it at the first sign of these initial symptoms can improve your healing time and even prevent painful open sores. After you've experienced this once, you'll likely be able to identify a cold sore easily if you experience a second breakout.

Stage 2: Blistering

One or two days after the initial signs of a cold sore breakout, one or more fluid-filled blisters emerge in the affected area. These can be painful, but with antiviral treatment, the symptoms can be alleviated. An over-the-counter pain reliever can also help at this stage.

Since active cold sores can spread the HSV 1 virus easily, it's important to avoid touching the area as much as possible and wash your hands frequently. Sharing food, drink, or cosmetics such as lip balm, kissing, and oral sex can all spread the HSV 1 virus, so it's best to avoid these until your blisters have healed and you're less contagious.

Stage 3: Weeping

While weeping may not sound appealing, at least the cold sore is getting closer to healing at this stage. The cold sore will break open and you may notice the fluid weeping out, leaving a red sore. Since the blisters are open, this is when you're most contagious, so it's important to avoid picking at your skin, keep washing your hands, and continue to be careful about sharing food or intimate activity.

Stage 4: Crusting

During this stage, the blister will turn yellow or brown and dry out. It may be tempting to pick at the dried-out blister, it's important to let it heal at its own pace.

Stage 5: Healing

In the final healing stage of a cold sore, it will form a scab. The scab will flake away on its own, leaving healed skin with no scar.

When should you see a doctor about your cold sore?

Since it's best to treat a cold sore at the very first sign that you may have a breakout coming on, it's a good idea to prepare for any future breakouts by having the appropriate medication on hand. That way, you won't have to spend precious time going to a doctor and waiting at a pharmacy for your treatment.

To be prepared the next time you experience a cold sore and nip it in the bud before it develops, start an online visit with Felix. You'll be able to connect with a healthcare practitioner and arrange to have doctor-prescribed medication sent right to your door, so your next blister won't stand a chance.

You may also want to speak with a healthcare provider if your outbreak lasts for two weeks or longer or if you're experiencing severe symptoms, such as a high fever. 

The takeaway

Cold sores are an annoying fact of life for many of us. While they can be painful and may not have you feeling your most confident, with treatment a breakout can pass relatively quickly. Being prepared for future breakouts by having medication on hand is the best way to ensure you can treat it fast and reduce the severity and duration of a cold sore.

It's also important to note that when a breakout is active you are more contagious and able to pass on the herpes simplex virus that causes cold sores. During a breakout, wash your hands frequently, especially after touching the affected area. This way, you can avoid infecting other parts of your face or other people. Refrain from sharing anything that may pass along the virus, such as food and drinks, until your breakout is healed.

WRITTEN BY
Felix Team
Updated on:
July 18, 2022
Medically reviewed by
Dr. Sheila Wijayasinghe
Family Physician, MD, CCFP
Disclaimer

The views expressed here are those of the author and, as with the rest of the content on Health Guide, are not a substitute for professional medical advice, diagnosis, or treatment. If you have any medical questions or concerns, please talk to your healthcare practitioner.

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