Stages of a Cold Sore Breakout

Cold sores typically last 1-2 weeks, although in some cases they may last up to a month.¹ It’s important to understand the stages of cold sore breakouts, as knowing where you are in the process can help you – or your doctor – determine the best treatment option(s).

The most common stages of a cold sore outbreak include:¹

  1. Tingling: 1 dayWhen cold sores begin forming, sufferers commonly report feeling a tingling or burning sensation around their mouth or lips. This sensation may last a few hours, or it may last up to a full day.
  2. Redness: 1-2 days During this stage of the cold sore breakout, sufferers often report the appearance of redness in the area of the outbreak. Additionally, it’s not uncommon for swelling to occur as a small bump begins to form.
  3. Bumps: 1-2 days – Swelling commonly gives way to the formation of a visible bump or bumps, which often occur in small clusters. These bumps commonly appear along the line where the lips meet the skin of the face, although they can also occur around the nose or on the cheeks.
  4. Blisters: 2-3 days – Vesicular lesions (blisters) and other small bumps begin to appear. These blisters are filled with fluid, and may burst, causing fluid to ooze from the open sore.
  5. Scabs: 5-7 days – The longest stage of the cold sore outbreak, the fluid and open sores created by the cold sore blisters and bumps begin to crust and scab. As these scabs shrink, it’s not uncommon for sufferers to experience painful cracking and splitting, which may lead to bleeding. Additionally, it’s not uncommon for someone suffering a cold sore outbreak to feel a severe itching and/or burning sensation during this phase.
  6. Redness: 1-2 days – In the final stage of the cold sore breakout, the scab falls off, leaving tender, slightly red skin behind to finish the healing process.


Additional resources:

How to Apply Sitavig

  1. WebMD (June 04, 2014). Cold Sores – Topic Overview [Skin Problems & Treatments Health Center web post]. Retrieved August 15, 2015, from
Indication & Important Safety Information


Sitavig® (acyclovir) 50 mg buccal tablet is indicated for

the treatment of recurrent herpes labialis (cold sores) in immunocompetent



  • Sitavig® (acyclovir) 50 mg buccal tablet should not be used in patients with known hypersensitivity to acyclovir, milk protein concentrate, or any other component of the product.
  • Sitavig has not been studied in immunocompromised patients. No interaction studies have been performed. Sitavig’s safety and efficacy have not been established in pediatric patients.
  • There are no available data on Sitavig use in pregnant women. However, published observational studies over decades of use of acyclovir have not identified a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. It is not known if Sitavig is excreted in breast milk; however, systemic exposure following buccal administration of acyclovir is minimal. Before administration, discuss if the patient is lactating or planning to breastfeed.
  • The possibility of viral resistance to acyclovir should be considered in patients who fail to respond or experience recurrent viral shedding during therapy.
  • In a controlled clinical trial, the most common side effects (greater than or equal to 1%) for Sitavig were: headache (3%), dizziness (1%), lethargy (1%), gingival (gum) pain (1%), aphthous stomatitis (canker

    sores) (1%), application site pain (1%), application site irritation (1%), erythema (redness) (1%), and rash (1%). In the same trial, these side effects ranged from 0% to 3% for placebo.

You are encouraged to report negative side effects of prescription

drugs to the FDA. Call

1-800-FDA-1088 or visit

Please see Full Prescribing Information.