What Causes Cold Sores?

The herpes simplex virus (commonly referred to as HSV-1) is the underlying cause of cold sores.¹ Cold sores are commonly spread among people infected with the HSV virus. Not only are cold sores contagious during a cold sore outbreak, but also during a process called “viral shedding”, which is also referred to as “asymptomatic shedding.” Viral shedding is the process by which a virus may be expelled and released from its host after successful infection and reproduction has occurred.² This process can occur even when no cold sore blister is visible, or no symptoms are present.²

Are cold sores contagious?

Many people have been exposed to the HSV virus – even if they never get cold sores. Once infected, the virus remains in your body for life. However, it often remains dormant most of the time. As a result, it’s possible for a person to contract the HSV virus from someone who wasn’t suffering a cold sore outbreak, or didn’t even know they had been infected.¹

Common cold sore triggers include:¹


  • Cosmetic, surgical or dental procedures
  • Sports injuries
  • Cuts from shaving


  • PMS
  • Pregnancy
  • Menopause


  • Weddings
  • Divorces
  • Reunions
  • Vacations
  • Graduations


  • Job pressure
  • Fatigue or lack of sleep
  • Finances
  • Exams
  • Work deadlines


  • Exposure to sunlight and wind
  • Exposure to cold, dry air


  • Viral infection or fever
  • Changes in the immune system
  • Kissing an infected person
  • Sharing food, drinks, or utensils (such as silverware, shaving razors or even towels) with an infected person

How can I protect myself from cold sores?¹

Although it’s impossible to completely safeguard yourself from contracting the HSV virus or suffering a cold sore outbreak, there are things you can do to lessen your chance of infection:

  • Wash your hands often, using hot water and soap – This is a best practice when it comes to overall hygiene, and it’s especially important when you’ve been around a person suffering from a cold sore outbreak.
  • Get plenty of rest – Lack of sleep and fatigue can lower your immune system’s ability to fight off infection. Getting the recommended eight hours of sleep per night can help keep your immune system working at full capacity.
  • Manage your stress – It’s hard not to get stressed out these days, but excessive stress does a number on your body. When you feel stress or anxiety coming on, try inhaling and exhaling deeply in a calm, soothing rhythm. Meditation may also be effective at fighting off the negative effects of stress and anxiety.
  • Protect yourself from the sun – If you know you’re going to be outside for any extended period of time, wear a hat to shade your face and lips from the sun. Seek shade whenever possible, and be sure to wear sunscreen with the proper SPF to protect your skin from the sun’s harmful UV rays. Finally, apply lip balm with moisturizer and SPF frequently throughout the day.
  • Keep warm when it’s cold – Cold, dry air and wind can dry out your skin and lips in a hurry, which can open the door for infection. When the temperature drops outside, protect yourself by covering your neck and face with a scarf. It’s also a good idea to moisturize your skin often, and to apply moisturizing lip balm with SPF frequently throughout the day, regardless of whether or not you plan to go outside.
  • Stay hydrated – As you may have noticed by now, dry skin opens the door for infections and other issues. Drinking plenty of water each day will help keep your skin and lips moisturized, which could help your body stave off a cold sore outbreak.


  1. WedMD (June 04, 2014). Cold Sores – Topic Overview [Skin Problems & Treatments Health Center web post]. Retrieved August 15, 2015, from http://www.webmd.com/skin-problems-and-treatments/tc/cold-sores-topic-overview
  2. The Free Dictionary by Farlex (no date). Viral Shedding [Medical Dictionary definition]. Retrieved August 15, 2015, from http://medical-dictionary.thefreedictionary.com/viral+shedding
Indication & Important Safety Information
Sitavig® (acyclovir), 50mg Muco-Adhesive Buccal Tablet is indicated for the treatment of recurrent herpes labialis (cold sores) in immunocompetent adults.
  • Sitavig should not be used in patients with known hypersensitivity to acyclovir, milk protein concentrate, or other components of the product.
  • Sitavig has not been studied in pregnant women or in immunocompromised patients and no interaction studies have been performed. Sitavig’s safety and efficacy have not been established in pediatric patients.
  • Sitavig is a Pregnancy Category B product; therefore it should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus. It is not known if Sitavig is excreted in breast milk; however, systemic absorption is minimal.
  • In a controlled clinical trial Sitavig's most common side effects (greater than or equal to 1%) 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 (1%) and rash (1%). In the same trial these side effects ranged from 0%-3% for placebo.
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch.com or call 1-800-FDA-1088. Click here for Full Prescribing Information.