Cold Sore Triggers and Treatment

Here is what triggers those painful blisters and how to get them under control

Why do I get cold sores on my lip? Can they ever go away? Is there something I can do for them? Are they contagious? These are all frequently asked questions worth addressing with patients.

Cold sores usually appear as grouped small blisters around the lips and can last anywhere from 1 to 3 weeks. In some people, they tend to recur, which often makes it an uncomfortable, embarrassing, and frustrating skin condition. In addition, some people experience a tingling and burning sensation around the lips preceding and during a flare.


What Is the Science Behind Cold Sores?

The scientific term for a cold sore is “herpes labialis,” which is a viral infection caused by the herpes simplex virus, usually, type I (HSV1). After the initial HSV1 infection, the virus hides in the sensory nerves to the face near the area of the primary infection. The virus remains contained by the immune system in a dormant state until something affects the immune system and allows the virus to reactivate. Unfortunately, there is no definitive cure for HSV1 and once infected, the virus remains within the body in the dormant form for life. Because cold sores are caused by a virus, they are contagious, especially in individuals who have never been exposed to the virus, or in people with a decreased immune system (such as those with HIV or undergoing chemotherapy for cancer). The virus is most contagious during an active break out.

Luckily, there are ways to prevent cold sores and keep the flares to a minimum.


Cold Sore Triggers

Triggers are things that can reactivate the virus and cause cold sores to appear. Below are some of the most commonly reported reasons.[1-3]

  • Stress
  • Menstrual period
  • Sunlight exposure
  • Decreased immune defenses
  • Trauma to the skin
  • Decreased sleep
  • A cosmetic procedure like chemical peels and facial resurfacing laser treatments


Prevention and Treatment

Anti-viral medications

Antiviral oral medications are widely used for herpes infections. Acyclovir and valacyclovir are some of the commonly used oral agents for herpes infections and can be used to prevent outbreaks, shorten the duration of symptoms, and reduce the severity of symptoms in patients experiencing cold sores.[1,4] 

Sun protection

Sunscreen is important to help prevent outbreaks of HSV1.[2] As previously stated, sunlight exposure is highly linked to recurrence of cold sores. A study was done on a population of 38 HSV1-infected patients, and the use of sunscreen was demonstrated to decrease the number of breakouts.[5] There are many lip-balm products with sun protection factor (SPF) that can be used on the lips, and facial sunscreens can be used for the skin.


Lysine has been attributed to helping minimize and prevent HSV1 symptoms. One study examined lysine supplementation and it was concluded that those individuals taking 1000mg of 1-lysine experienced significantly fewer lesions than those who were taken off of the lysine supplementation.[6] More studies are needed to determine other studies that can lend more support for lysine so that there is a better understanding of how lysine can be dose and its potential side effects.

Applying local heat

Heating topicals are very popular when discussing treatment for cold sores. There are all sorts of lipstick shaped applicators and spot creams that can be found in convenience stores. The use of heating topicals on sores has been reported to reduce the duration of symptoms, such as burning, itching, and swelling.[7]


Finally, Are Cold Cores Caused by the Common Cold?

The immune system is pivotal in helping us fight off all sorts of infections and ailments. Contrary to popular belief, cold sores are not directly caused by the common cold; rather they are caused due to a decrease in our immune cell function, which alters the body’s ability to fight off infections properly. Ultimately, there are several factors that can help boost the immune system, such as good sleep hygiene, proper diet, exercise, and lifestyle.

* This Website is for general skin beauty, wellness, and health information only. This Website is not to be used as a substitute for medical advice, diagnosis or treatment of any health condition or problem. The information provided on this Website should never be used to disregard, delay, or refuse treatment or advice from a physician or a qualified health provider.


  1. Opstelten W, Neven AK, Eekhof J. Treatment and prevention of herpes labialis. Can Fam Physician.2008;54(12):1683-1687; PMID: 19074705 Link to research.
  2. Ichihashi M, Nagai H, Matsunaga K. Sunlight is an important causative factor of recurrent herpes simplex. Cutis.2004;74(5 Suppl):14-18; PMID: 15603217 Link to research.
  3. Psychological stress and other potential triggers for recurrences of herpes simplex virus eye infections. Herpetic Eye Disease Study Group. Arch Ophthalmol.2000;118(12):1617-1625; PMID: 11115255 Link to research.
  4. Worrall G. Herpes labialis. BMJ Clin Evid.2009;2009PMID: 21726482 Link to research.
  5. Rooney JF, Bryson Y, Mannix ML, et al. Prevention of ultraviolet-light-induced herpes labialis by sunscreen. Lancet.1991;338(8780):1419-1422; PMID: 1683420 Link to research.
  6. Thein DJ, Hurt WC. Lysine as a prophylactic agent in the treatment of recurrent herpes simplex labialis. Oral Surg Oral Med Oral Pathol.1984;58(6):659-666; PMID: 6438572 Link to research.
  7. Wohlrab J, Voss F, Muller C, et al. The use of local concentrated heat versus topical acyclovir for a herpes labialis outbreak: results of a pilot study under real life conditions. Clin Cosmet Investig Dermatol.2013;6:263-271; PMID: 24231728 Link to research.