Terrible breakouts aren't the only potential side effect. Read this before your first appointment.

By Daley Quinn
Photo by Getty Images

It’s been about two years since I suffered from the worst cold sore of my entire life. I’ve always been prone to cold sores, and usually get them after a long flight or when I’ve been out in the sun a wee-bit too long. Do I get self-conscious about them? Sure, but not enough to prevent me from living my best life. That was until I tried a new facial laser treatment and woke up a few days later with a terrible breakout and a giant monster atop my lower lip.

I hadn’t really called out sick at work very often, so when I texted my boss to tell her that I had developed a cold sore the size of Europe on my lower lip and was ashamed to come into the office that day, she said, “Wow, really? It’s that bad?” I told her that I could send her a picture of the monstrosity, but she unsurprisingly declined my offer and graciously let me work from home that day.

For weeks thereafter, I racked my brain for reasons why I had developed a cold sore like that, and how in the world it could have grown that big. I then realized that the two lasers used on my face during a facial had caused my skin to break and the virus to spread to my lip. To make matters worse, I hadn’t checked the box on the new client form that said, “Yes, I am prone to cold sores.” Had I let my esthetician know that I was prone to getting cold sores, she probably wouldn’t have used those lasers on me, or she would have decreased their strength at least.

To satisfy my own curiosity, I’ve asked the experts about the six other things that could happen post-laser treatment. While most are unlikely, it’s important to consult your doctor or dermatologist before undergoing any type of laser. Be aware of these afflictions, and if you’re prone to cold sores, do yourself (and your lips) a favor and check that box!


Lasers zap away freckles or stimulate collagen growth by producing a precisely targeted injury to the skin. “That injury can temporarily agitate the melanocytes in the area, which are the cells in our skin that produce tanning pigment,” explains Kenneth Howe, MD, NYC-based dermatologist. “That agitation is usually not a problem, unless a patient gets sun too soon after the laser procedure.” If that occurs, the already agitated melanocytes are then over-stimulated by sunlight exposure, and the result is hyperpigmentation. Bottom line: stay out of the sun, or at least don’t get any color, for a month after a laser treatment.


It’s pretty normal to experience some redness and swelling after a laser treatment. “What can be unexpected, though, is that, depending on the depth...of the laser procedure, the redness could persist for months,” says Hadley King, MD, NYC-based dermatologist. “The aggravation of a preexisting skin condition like rosacea could contribute to this redness.”

Acne flare ups

If you’re an acne-prone gal like myself, expect to see pimples develop after an intense laser treatment, such as Fraxel. “[Acne flare ups] probably happen because hundreds of tiny channels have been opened in the skin by the laser treatment,” says Howe. “They heal up within 36-48 hours, but in the meantime, if heavy moisturizer or makeup is applied, the skin can get clogged up.”


Cold sores

Cold sores are caused by the herpes simplex virus, and Johns Hopkins Medicine says 50% to 80% of the population has it. “If the laser treatment is one that breaks the surface of the skin—such as a Fraxel laser—then we run the risk of the herpes virus spreading beyond a usual localized outbreak (typically on the lip) into a more widespread one,” says Howe. “The broken skin surface provides the perfect field for the herpes virus to spread.” To prevent this from happening, a lot of doctors will prescribe a course of Valtrex, starting three days before their Fraxel treatment.


Scarring almost never happens anymore, but that wasn’t the case back in the day. “Over 15 years ago, we used to see scarring from continuous wave lasers, which caused white waxy changes to the skin, especially around the mouth,” explains Howe. “But the technology has improved so that doesn’t happen anymore, and the new lasers deliver energy in discrete pulses, so the skin has time to cool and recover, and doesn’t overheat.”


Burns can happen during laser treatments, but Howe assures us that it’s very, very rare. “One thing that can increase this risk is having a fresh or deep tan,” explains Howe. “Certain lasers are used to attack pigment—to treat freckles or melasma—and if the normal skin is deeply tanned, the laser will attack the normal skin, as well, resulting in a burn.”


Ectropion occurs when the laser resurfacing is done close to the lower eyelid, and it’s possible for the skin of the eyelid to turn outward as the skin heals. “This is a pretty rare occurrence, and surgery would be necessary to correct this,” says King.