The Academy of General Dentistry says that cold sores follow five stages: prodrome, blister, ulcer, crusting and healing. A cold sore is most contagious during the early stages. That's also when it's most responsive to treatment with prescription antiviral drugs, says Northeastern Ohio University internist Christina Cernik, M.D., in a 2008 edition of "Archives of Internal Medicine." According to Cernik, drugs may have no effect at all when they're started more than four days after a cold sore appears.
Prodrome
Doctors use the term "prodrome" to refer to premonitory symptoms that precede the full-blown disease. In the case of cold sores, says Cernik, about 60 percent of patients experience tingling, burning, stinging, sensitivity or numbness at the site where blisters later appear. The prodrome may begin as little as a few hours before the next stage of the infection, or it may start up to two days in advance, according to MayoClinic.com. Some people also experience flu-like symptoms such as fever, headache, muscle pain, decreased appetite and a generalized sense of malaise. These symptoms may persist until the late stages of the infection, when the cold sores start to crust and heal.
Blistering
In the 2008 edition of "Harrison's Principles of Internal Medicine," University of Washington Professor of Virology Lawrence Corey, M.D., describes the characteristic evolution of a cold sore. The blisters, says Corey, start out as painful bumps that develop into 1- to 2-mm blisters, filled with yellowish fluid, over the course of a few hours. In fact, the process happens so rapidly, according to Corey, that most patients never notice the bumps. Blisters can occur on their own as isolated lesions, but more often they occur in clusters that sometimes coalesce into larger lesions. The blisters usually produce pain that many patients describe as throbbing or severe aching, accompanied by loss of sensation in the surrounding skin.
Ulceration
Between 72 and 96 hours, according to Cernik, the blisters spontaneously rupture, ushering in the next stage of the cold sore, the ulcer stage. Ulcers appear as shallow, dark pink or red abrasions with sharply defined borders that doctors sometimes refer to as "punch-out" lesions, notes Corey. This is the most infectious stage of the cold sore. The ulcer typically "weeps" clear fluid laden with infectious particles. Patients should wash their hands after handling the lesions and take care to discard or thoroughly clean any objects that come in contact with them to avoid spreading the infection to other people or other sites on the skin. The ulcer phase usually lasts just one or two days. A change in color from pink to yellow-gray heralds the next stage of the cold sore, crusting.
References
- Academy of General Dentistry: What Are Cold Sores?
- "Archives of Internal Medicine"; The Treatment of Herpes Simplex Infections: An Evidence-Based Review; Christina Cernik, M.D., et al.; June 2008
- "Harrison's Principles of Internal Medicine, 17th Edition"; A. S. Fauci et al.; 2008
- MayoClinic.com: Cold Sore: Symptoms
