In laser hair removal, light energy is transferred to key areas in the hair follicle. Wavelengths of light energy blow up cells and structures needed for hair growth in these locations. It is important to note hair growth is not permanently stopped by laser treatments; it is reduced. Thus, lasers are said to be used for hair reduction, not removal.
The key area for hair growth is called the hair bulge or bulb. It is fairly deep in the skin, making sufficient laser energy penetration to that level difficult. Lasers must generate enough power to blow up enough melanin in the hair bulge to alter hair growth. Laser light may be prevented from reaching deeply into this portion of follicle if it hits other targets higher up like melanin in the skin or hemoglobin in blood vessels. These can absorb the intended energy too.
It is important to understand that laser hair treatments are tricky. Not all lasers work well for hair reduction. Not all settings, practitioners, and skin types obtain good results. The bottom line is hair reduction laser treatments are actually difficult to do well. The fact that there are so many hair removal lasers and light machines on the market is a testament to this.
Another important nuance to treatment success is hair growth cycles. Only actively growing hairs can be treated. Hair growth goes between 3 cycles: growth (anagen), rest (telogen) and the transition phase between growth and rest called catagen. Every person’s hair follicles cycle at different rates, even follicles in different areas of the body cycle at different rates. Again, only during the anagen phase of growth can a laser treatment work to reduce hair. This is one of the reasons laser treatments have to be repeated to hopefully capture all follicles in their anagen growth phase. Your laser operator need to know the proper interval for treatment if they are to capture all follicles in a treatment area over the course of your treatment sessions.
Laser hair treatments also have side effects. One particularly vexing side effect is actually hair growth stimulation! The treatments consequently encourage and stimulate hair to grow. Doses that are too low to blow up the melanin at the hair bulge actually stimulate hair growth. Used on the scalp, this concept is now marketed to reverse balding.
Another devastating side effect is dyspigmentation. The laser’s light energy causes heat in the skin. If laser light blows up melanin or other targets like hemoglobin, it causes a burn. Tanning is to be avoided during laser and light hair treatments. Operator experience is also vital.
More Laser Hair Reduction Side Effects
- Scarring: If this occurs, a wound of significant size was made. There may be a color change in the overlying skin. There may be a lump, keloid, or indentation.
- Hyper-pigmentation: This is when wounds heal with excess pigment (post inflammatory hyper-pigmentation). When the pigment drops down into the second layer of the skin, it may be permanent or it may eventually fade. Sun protection helps improve this condition.
- Hypo-pigmentation: These wounds heal with less pigment. One reason could be that pigment cells (melanocytes) are destroyed or reduced as part of the injury and healing process.
- Blistering: This happens as part of a burn from excess laser power being absorbed into melanin or other structures. Blisters can also occur if the herpes virus is activated by the laser treatment. Painful blisters are an indication to call your doctor immediately.
- Scabbing: Like a blister, this happens due to tissue injury from laser treatment.
- Thrombophlebitis: Laser light can target hemoglobin, heating it up and damaging blood vessels. This may cause inflammation and small clots in the vessels called phlebitis.
Each State Has Different Rules for Who Can Legally Perform Laser Treatments
Training to operate a laser varies from physicians where years of supervised laser study and training are required, to non-physicians who are hired by separate entities. Here are some key questions to ask before selecting a laser treatment facility:
- Is the facility owned by a doctor?
- Is a doctor on-site during treatment hours?
- What are the emergency procedures?
- Who is doing your treatment?
- Will a doctor, nurse, or a non-medical person be doing the procedures?
- What training and years of experience in laser do they have?
- How many patients in a week do they perform this procedure on?
- Have they treated your skin type before?
- Is your medical history routinely taken before each visit? Some drugs and medical conditions increase the risk of side effects.
- Will they test a small patch of skin to be sure the machine meets the expected response?
- Is the machine good for your skin and hair type?
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Sean W Lanigan, MD, FRCP, DCH Correspondence information about the author MD, FRCP, DCH Sean W Lanigan