Aesthetic Dermatology

Expert shares laser hair removal clinical pearls



Hair removal has been ranked as the most commonly litigated procedure in laser surgery, although fewer procedures for hair removal are performed annually than for other applications, Kristen M. Kelly, MD, said at the annual Masters of Aesthetics Symposium.

Dr. Kristen M. Kelly, professor of dermatology and surgery at the University of California, Irvine

Dr. Kristen M. Kelly

Clinicians perform an estimated 445,000 laser hair removal procedures each year, trailing those performed for wrinkles (561,000), facial redness (598,000), and sun damage (610,000), according to the 2017 American Society for Dermatologic Surgery Procedures Survey. However, hair removal has been found to be the most common procedure resulting in litigation (JAMA Dermatol. 2013;149[2]:188-93), “which is what we want to avoid,” Dr. Kelly said. “We want to learn how to do it in the best way possible.”

Dr. Kelly, professor of dermatology and surgery at the University of California, Irvine, pointed out that clinicians are targeting melanin during laser hair removal. “This is important because it means that gray, white, blonde, and in some cases, red hair are not going to respond very well. In order to reach stem cells in the hair follicle, you can’t use superficial wavelengths, so we end up using the 755-nm alexandrite laser, 810-nm diode laser, or the 1064-nm long-pulsed Nd:YAG laser for the most part in order to get our result. You can also use intense pulsed light at 590-1200 nm.”

The pulse duration should be on the order of the thermal relaxation time (TRT) of the target. She defined thermal relaxation time as the duration required for the heat generated by absorbed light energy within the chromophore to dissipate to 50% of its value immediately after laser exposure.

“We want that heat to be absorbed by the melanin in the hair,” Dr. Kelly said. “Then we want that heat to radiate out to the hair follicle and the stem cells, which is going to prevent the hair from coming back in the future.” Epidermal cooling via cryogen spray cooling, contact cooling, or air-cooling allows clinicians to use higher fluences, allows for the use of safe treatment of darker skin types, and decreases treatment discomfort.

Prior to performing laser hair removal on the perioral area, Dr. Kelly provides a prophylactic antiviral medication for patients with a history of herpetic infection to suppress recurrence. She also advises patients to remove sunless tanner or other products from the skin surface, and she shaves or clips hair close to the surface gently, avoiding abrasion or surface damage. Most of the time she does not use a topical anesthetic. “You always want to make sure the laser is functioning properly by checking the laser’s cooling components, etc.,” she said. “I always tell patients, ‘8-10 treatments is not uncommon. You’re going to have fewer hairs and thinner hairs, but it doesn’t mean that you’re going to have zero hairs in this area for the rest of your life.’ Set the expectation correctly.”

Patients should wear protective goggles if being treated in areas other than the face. “If being treated on the face, make sure they’re wearing appropriate protective eyewear such as laser safe eye shields. Those performing the treatment should wear surgical masks and use a smoke evacuator, as there are multiple known carcinogens and environmental toxins in the plume generated by laser hair removal,” she said (JAMA Dermatol. 2016;152[12]:1320-6).

Factors to consider in choosing treatment settings include hair color, the patient’s skin color, hair thickness, hair density, and body location. For example, the genital area may be more pigmented in some patients, and also may be more sensitive. “If you have thicker and darker hair it’s going to absorb more energy, so you have to adjust your settings,” Dr. Kelly said. She also avoids treating acutely tanned patients. “What you don’t want is for a tanned patient have a complication. I’d rather have them wait 2 or 3 weeks and come back. Sometimes it frustrates them a little, but it is safer.”

At the start of each procedure, Dr. Kelly delivers a couple of pulses then asks patients how uncomfortable they are on a scale from 1 to 10. “It often will vary,” she said. “Even if I’ve seen a patient for 10 treatments, some days it will hurt a little more than others. If the patient says it hurts a lot more than it normally does, you need to stop and think. That tells you that something is not right. They might be too tanned, or perhaps the [device] settings are wrong or the laser’s not functioning properly. Monitor the skin response. It takes time to see the final skin response, so wait before adjusting the energy. You want to see mild redness or mild follicular response. People report a little bit of a burning sensation.”

Postprocedure, she routinely applies a topical steroid such as betamethasone or clobetasol immediately after treatment. “That calms down the inflammatory response. If I see an area that I think is going to blister, I will apply the steroid multiple times until I see that response go away.” She asks patients about their pain level and typically applies ice to the treated area for 10 minutes before they leave the office, and they head home with after-care instructions, including a phone number where Dr. Kelly can be reached if patients have concerns. “I call my patients in the evening to ask how they’re doing, and if they have any questions.”

Dr. Kelly does not do laser hair removal inside the eye orbit or between the eyebrows, “because even with eye shields, you can have a problem,” she said. A potential outcome to be aware of is paradoxical hypertrichosis, or increased hair growth after laser hair removal estimated to occur in 0.6%-10% of patients. She discusses this with patients when consenting them. “Some people say this occurs in darker skin types, while others say it happens in people with thicker hair or thinner hair. Some of it occurs on the edges of the treatment area.” The treatment for paradoxical hypertrichosis is to continue laser hair removal and “try to push the energy just a little bit, but be cautious. It can be a difficult problem to resolve.”

Dr. Kelly has noticed a recent uptick at her practice in gender transition patients seeking hair removal procedures. “Removing facial and chest hair may be desirable, and may be covered by the patient’s health insurance,” she said. “Multiple treatments are required. A thick beard area needs to be approached cautiously.”

She referred to future advances in laser hair removal that may involve the use of topical agents to improve outcomes. For example, Sienna Biopharmaceuticals has developed Topical Photoparticle Therapy which, according to its website, uses “silver particles to absorb laser light and convert the light energy into heat to facilitate local tissue injury ... in the case of unwanted light or mixed pigment hair, which can’t be removed with lasers alone, [this process] targets the hair follicle.”

Dr. Kelly disclosed that she is an advisory consultant to Syneron Candela and Allergan. In addition, Allergan has provided drug products to Dr. Kelly for research purposes, while Solta Medical and ThermiRF have provided her with donated light sources for research or clinical use. Dr. Kelly has also received funding from the Sturge-Weber Foundation, the American Society for Laser Medicine and Surgery, and the National Institutes of Health.

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