Cold sores, caused by the HSV-1 virus, can be very common and triggered by different environmental or health causes throughout a person’s lifetime. One of the main concerns that can trigger a new cold sore to flare up is exposure to sunlight.1

Although it is not known in its entirety what triggers the cold sore virus – which mainly resides in the facial nervous system – they do appear more frequently when illness or compromised immune systems are present1. Among the more common causes such as stress and injuries, sunlight – UV radiation – may also play a role in triggering new cold sores.1

As you may already know, too much UV radiation from the sun can cause sunburn and pre-mature aging.  But what you might not realize is that it can also jeopardize your immune system and slow down your body’s ability to fight infections.1 Therefore, keep this in mind next time you spend time in the sun, as it may be the reason behind your next cold sore breakout.

If you feel a cold sore coming on from any of the different causes, including sunlight, talk to your physician about cold sore treatment options or ways to stop them before they start, and ask if prescription Sitavig® (acyclovir), 50mg Muco-Adhesive Buccal Tablet is right for you.


1- McCahon, J. (August 16, 2013). Sunlight & Cold Sores [web log post]. Retrieved August 15, 2015 from


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 pain (1%), aphthous stomatitis (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 or call 1-800-FDA-1088.

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