Lasers in Dermatology: Science and Uses

Dr. Geronemus

Lasers in Dermatology: Here I am visiting Dr. Geronemus at his office, which specializes in cosmetic dermatology, laser therapies, and Mohs.

A few weeks ago I visited Dr. Roy Geronemus, a world-renowned laser guru and seasoned dermatologist, at Laser & Skin Surgery Center of NY, and I became exposed to the world of lasers in dermatology for the first time. It. Is. Fascinating. I felt like I was in a laser playground with all these cool toys to use (yes, it made me think of Dr. Evil too). I’ve been reading a ton about lasers and how they work and I figured you guys would want to know too! Here’s a closer look at how we use lasers in dermatology.

How do they work


I personally think freckles are cute. But there are people out there who want them ALL GONE.

Lasers work by selectively targeting certain molecules that absorb the laser light in the skin, mainly blood, water, or melanin (pigment). When laser light is absorbed, that light energy is turned into heat energy, and the higher temperatures actually destroy the target. Different wavelengths of lasers will target different things in the skin; for example the pulse dye laser targets blood because it has a 585-600 nm wavelength so it destroys blood vessels. Another laser called the ruby laser targets melanin (pigment), so it can be used for freckles and sunspots. Each laser targets and destroys something specific in the skin while leaving other structures more or less intact, and we have used this potential to our advantage in dermatology.

Dr. Evil Lasers

Dr. Evil is into lasers

What lasers can treat (a non-comprehensive list)

  • Targeting BLOOD
    • Small dilated blood vessels (telangiectasias)
    • All around redness in the case of rosacea
    • Port-wine stains
    • Cherry angiomas and other small vascular spots
    • Venous malformations
  • Targeting PIGMENT
    • Tattoo removal (more on that below)
    • Freckles
    • Sunspots
    • Hair removal (targets the pigment in the hair follicle)
  • Targeting WATER
    • Photorejuvenation (more on that below)
    • Scars
    • Warts

Tattoo removal

Multicolored tattoo

Gorgeous tattoo, lots of colors. Not so easy to remove.

Believe it or not, different colors of tattoos are variably difficult to remove and may require different lasers depending on the color. Black tattoo pigment is the easiest to remove because it absorbs all laser wavelengths. Different lasers are used for different colors; blue and green tattoo pigments are targeted by one laser and red and yellow tattoos are targeted by another. Tattoos are hard to remove to begin with and require multiple treatments to get rid of the color. So if you come in with a large multicolor tattoo, you will be looking at many many treatments because you need multiple lasers to target different colors. Unfortunately there can be side effects of tattoo removal, including permanent whitening or darkening of the skin, allergic reactions brought on by the lasers releasing the tattoo pigment, rashes, and sometimes even a paradoxical DARKENING of the tattoo (happens with beige, red, white, or light brown tattoo pigments). So definitely talk to your dermatologist at length about risks and benefits before going through with the procedure.

laser resurfacing wrinkles

Lasers can be used for static wrinkles, fine lines, blemishes


There are two rough categories of photorejuvenation: ablative and non-ablative. Ablative refers to an intensive and invasive treatment that basically destroys the upper layer of skin, and non-ablative is a non-invasive approach that work on the deeper layers of the skin and leave the upper layers intact. As you can expect, the ablative one takes longer to heal (you look straight up scary for the first week or so) but you get better results. The ablative form is also more painful, so you need some sort of anesthesia, either local anesthetic injections or IV anesthesia with an anesthesiologist in clinic. The non-ablative treatment can be uncomfortable but topical anesthetic usually does the trick. The thought behind the mechanism of action is that by destroying parts of the skin you promote a wound healing response with increased collagen formation, improved laxity, and that once you heal, your skin will look overall better. This is a way to get rid of static wrinkles (read more about static vs. dynamic wrinkles and why Botox is better for dynamic ones here) and fine lines without going under the knife for a facelift. Just to be clear, a facelift surgery will usually have more drastic instant results; laser resurfacing produces more subtle results but at a lower price point with fewer risks. Each is good for different types of patients depending on risk factors, finances, and desired outcome.

Another distinction is fractional resurfacing, a technique that involves destroying columns of skin while leaving other columns intact. This is in contrast to blanket destruction of all the skin, which takes longer to heal with more side effects. This fractional resurfacing method forms a microscopic grid of treated and untreated skin, allowing for more intact normal untreated skin in place to heal faster. There are fractional ablative and fractional non-ablative lasers (I know, it’s confusing! This took me a while to learn too); for all the nuances of which to choose for your skin type, talk to your dermatologist.

There are potential complications to photorejuvenation treatments, especially with ablative laser treatments. Things to watch out for include acne or cyst like eruptions post-treatment, rashes, infections, and scarring.

Combining lasers

Your dermatologist may choose to use different lasers to achieve an overall effect. For example, if you want photorejuvenation as well as elimination of a few dark freckles and a few large visible blood vessels, your derm may use a combination of a resurfacing laser for photorejuvenation, plus a laser that targets pigment for the freckles, plus a laser that targets blood for the vessels.

darker skin types laser treatment

Talk to your dermatologist about the laser type that is suitable for your skin!

Different skin types

Depending on your skin type your doctor may choose to use a different laser. The reason for this is darker skin types contain more melanin, so when deciding on therapy, dermatologists need to choose a laser type that will not target the patient’s natural melanin in their skin. Obviously if the natural melanin is also targeted, then the patient will suffer from changes in color of their skin. Laser choice is so important to minimize side effects!


Lasers are VERY expensive to purchase and you need a new laser for each specific target. As a side note, many smaller dermatology offices only have a few lasers, but they can probably refer you to a larger center depending on your laser needs.

I’ve heard of some of the newest and fanciest lasers costing up to $100,000 to purchase! It may also take multiple sessions to treat whatever it is you want to remove, so these treatments can be costly. But here’s a big protip: Go to a licensed board certified dermatologist for your procedure because they are the ones who are fully trained in the equipment and know how to deal with all the potential complications. I’ve heard too many stories of people who want to save a buck and they go to someone who’s not a dermatologist, or who is not a doctor or supervised by a doctor, and they get botched results. Of course then these patients end up at a dermatologist’s office and end up paying more and sometimes it cannot even be fixed because the damage has already been done. This is YOUR FACE and YOUR BODY. Do you really want to take a chance on that? I wouldn’t.

Whew! This ended up taking way longer than I expected to write, mostly because I was learning and researching and reading my textbook along the way to put together this post. But if I learned this much, hopefully you gained something useful too. As usual, leave your questions and comments below!

For more information:

Science proven wrinkle removers in NYTimes

For anyone with access to academic journals, here is a review paper from Cutis

DermnetNZ (wikipedia for derms)

Disclaimer: This post was written on my own and is not associated with or representative of the views of Laser Skin & Surgery Center of NY or NYU.

2 Comments on Lasers in Dermatology: Science and Uses

  1. Senushi O'Sullivan
    June 13, 2017 at 12:29 pm (8 months ago)

    Hi Joyce! I’m a family med resident and blogger. Wanted to ask you if you knew of any new lasers on the market that are especially good for hair removal on dark skin. Looking forward to hearing your thoughts on this. Thanks!

    • Joyce
      June 27, 2017 at 2:29 pm (8 months ago)

      Great question! Not new lasers that I know of (though new ones are coming out all the time!) but ones we typically use include longer wavelength lasers like ndYag which targets the surface melanin less


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