You should know the side effects of laser hair removal before your first session. Skin tone, hair color, and planning all matter.
Most side effects are short-lived and consist of redness and swelling. More problematic side effects are uncommon and include burns, blisters, and skin color changes.
How Laser Hair Removal Works and Who It Suits
Lasers work on the principle that the pigment (color) in your hair absorbs light, which creates heat to damage the part of the root that produces new hair. Think of the pigment in your hair as the “target” of the laser light. The pigment in your skin also absorbs the laser light, and thus “competes” with the hair for the laser light energy.
Hair roots go through cycles of growth and rest. Growing hair can be most effectively treated. With time, hair that was resting at the time of an earlier treatment will grow and can be treated in subsequent sessions.
For this reason, laser hair removal consists of a series of treatments. The first course of treatments usually consists of 6-9 treatments, given 4-8 weeks apart, followed by maintenance treatments as needed.
Laser hair removal is intended to reduce hair for a long period of time, so that you will not need to shave or wax as often. It is hoped that hair will also grow back finer and lighter. Your hair color and type matter:
- Dark, coarse hair: The ideal target for laser hair removal
- Light blond, gray, and white hair: There is not enough pigment for the laser to work well
- Red hair: The pigment in red hair does not absorb laser light as well, although darker auburn hair may respond differently
- Fine, light hair on the face: Not as good a target as coarse hair on the chin
Laser hair removal is one of the many cosmetic services that we offer, and can be used on the face, underarms, “bikini” area, legs, back, chest, and other areas of the body.
What Happens After a Session
When the heat is created in the hair root to damage it, the skin around the hair is also heated, and thus a short-lived skin reaction is normal. Hair in the treated area will fall out over the course of days and weeks after treatment, so it is normal that you still see hair right after a laser hair removal treatment.
Normal skin reaction after laser hair removal (bumps) looks different from blisters, pus-containing bumps, and a spreading rash.
Why Do Complications Happen?
When the appropriate type of laser and settings are used for your skin and hair type, complications are uncommon.
If too much heat is generated in your skin, you may develop a burn and/or blister. This can result in a scar, or a light spot in your skin. Dark marks after inflammation (post-inflammatory hyperpigmentation) can also occur.
Other possible side effects include inflamed bumps around the hair, itchy “hive-like” rash, flare of a cold sore, and whitening of treated hair. There can even be an increase in the amount of hair in the treated area or nearby (“paradoxical hair growth”), for unclear reasons.
Are Side Effects Different on the Face?
Skin darkening after inflammation (“post-inflammatory hyperpigmentation”) and cold sores around the mouth can occur after laser hair removal of the face. Increased hair growth after laser hair removal is most often reported on the face and neck, but can occur in other areas as well.
Laser hair removal should not be performed on the eyelids or eyebrows, or in the bony socket of the eye, because the skin of the eyelid is thin and structures of the eye absorb light.
If you are developing increasing amounts of coarse hair on your face, and especially if your menstrual periods are not regular, you should be evaluated for a hormonal problem, such as polycystic ovarian syndrome.
Note that facial hair does not always indicate a hormonal problem, and if you only have a few stray hairs and your menstrual periods are regular, you probably do not need hormone testing. Hair that appears suddenly or grows quickly, or comes with a deepening voice or an enlarging clitoris, calls for prompt evaluation, even with regular periods.
If you do have a hormonal problem, treating it may help you maintain the results of laser hair removal, although more treatments may be needed. Treating the hormonal problem may help to prevent further hair growth, but laser hair removal will not fix the hormonal problem.
How Your Skin Tone Changes the Risk
The deeper your skin tone, or the more recently you’ve tanned your skin, the more potential there is for the pigment in your skin to compete with your hair. This makes the surface of your skin more susceptible to injury from excess heat. Feel free to ask any practice you’re considering how often they’ve treated someone with your skin tone.
When treating deeper skin tones, certain measures can help protect your skin. These include:
- Wavelength: Using a longer wavelength that skin pigment is less likely to absorb
- Pulse length: Using longer pulse length to let the heat dissipate from the skin’s surface as the hair is heating up
- Cooling: Using sufficient cooling to protect your skin’s surface, but cooling can’t make an unsuitable treatment safe
- Balanced settings: Balancing your settings carefully to make sure they’re not too low, which can lead to poor results
- Test spot: Doing a test spot to check your skin’s response (although this doesn’t guarantee how you’ll respond to future treatments, as your skin can change, such as if you tan or take a new medication)
Lowering Your Risk Before, During and After a Session
Make sure you don’t tan, go in a sunbed, or use self-tanner before your treatment. Also make sure you shave and don’t wax, pluck, or do electrolysis (these 3 remove the root that the laser targets; shaving doesn’t remove the root). We’ll let you know how long before your treatment you should do these.
Only use numbing cream as instructed by your treatment team, as using too much, over too large an area, if your skin isn’t completely intact, for too long, or wrapped can lead to dangerous absorption.
Laser hair removal is performed by our licensed aestheticians under the direction of our dermatologists. Before your first treatment, a dermatologist sets your treatment plan, and your aesthetician carries it out, reviewing your skin, hair and health history at each visit. We will select the appropriate settings for your hair color, hair thickness, body area, and skin.
Everyone in the room will wear eye protection matched to the laser for your entire treatment, as even a quick exposure to laser light can permanently damage your eyes, even if your eyelids are closed.
During your treatment you may feel heat or a snapping sensation with each pulse of the laser. This is brief, and everyone’s comfort level varies. After your treatment, you may use cool compresses if you’re uncomfortable, and you should be gentle to the treated skin, avoiding rubbing, scratching, or picking the skin.
You should wear a broad spectrum, water resistant sunscreen of SPF30 or more every day after your treatment series, and also between your treatments. You should also try to stay in the shade, and wear covering clothing.
Also follow our instructions after each treatment regarding heat and exercising. We will see you regularly to make sure your treatment is going well from the beginning, and we’ll adjust your treatments as necessary in a thoughtful way together.
Before You Book
Your evaluation covers your skin type, tone and goals, plus your medical history, every medicine and supplement, and your skincare products. Recent sun exposure or a history of cold sores or genital herpes may change or delay the plan. If you take a prescription acne pill (isotretinoin) or took one recently, tell us so we can set your timing together.
Skin recently treated with a peel, laser treatment or other procedure needs to heal fully first, however long that takes. We postpone treating any area with an active infection or a herpes outbreak, such as a cold sore or genital herpes, or the tingling that can signal one, until the skin heals.
With an active tan or self-tanner, we postpone treatment until it fades. Elective treatment waits during pregnancy, since too little research covers that time.
We work around tattoos and permanent makeup, whose ink absorbs the energy. The laser skips moles, because it can change how a mole looks and make later checks harder. A history of raised scars (hypertrophic scars or keloids) or unusual scarring calls for an individual review.
Past treatment with gold-based medicine needs a specialist's review first. We review each medicine that makes skin more sensitive to light, and you should never stop a prescribed one on your own.
After your session, redness and small areas of swelling around each hair opening often settle within one to three days. Warmth or mild sunburn-like discomfort often eases within hours, and some people notice itching.
Burns, blisters and crusts are complications that need checking, never a sign that treatment worked. Darker or lighter patches can follow; darkening after inflammation can take months to fade, and some color changes can last indefinitely. A burn or other injury can also leave a scar.
Other complications include more hair growing in or near a treated area, treated hair turning white, and inflamed bumps around hairs, sometimes with pus. Treatment can also trigger a cold sore or genital herpes flare, particularly near a spot that has had one. An intensely itchy, hive-like rash can appear hours or days later and persist, unlike the brief bumps of a normal reaction.
Get emergency or urgent care now, without waiting to reach our office, for any of these:
- Trouble breathing, a seizure, or an irregular heartbeat after using a numbing cream (emergency care)
- Signs of a severe allergic reaction, such as swelling of the tongue or throat, a tight throat, trouble breathing, or feeling faint, with or without hives (call 911)
- New eye pain, new or worsening blurred or reduced vision, a new dark or blind spot or other change in vision, or marked sensitivity to light, during or after a session (urgent eye care)
- A burn that looks deep, skin that turns white or charred, or severe blistering over a large area (urgent care)
- Redness or pain that is increasing quickly (urgent care)
- Fever, chills, or feeling unwell when the treated skin may be infected (urgent care)
Contact our office promptly for any of these; the last three call for a plan review rather than emergency care:
- Blisters, scabs or open areas on treated skin
- Pain, redness or swelling that is increasing
- New pus-filled bumps
- A cold sore or genital herpes sores in or near the treated area
- An intensely itchy, hive-like rash that does not settle
- New darker or lighter patches of skin
- Treated hair turning white
- More hair growing in or near the treated area
This article is general education rather than a diagnosis, and it does not replace an evaluation.
Care Planned Around Your Skin
We provide physician-directed care. Get an individualized evaluation at our South Loop dermatology practice to determine the treatment plan for you. We use evidence-based medicine to determine the initial laser settings for your skin and hair type.
We will modify these settings as needed based on how your skin reacts to the treatments you receive. Our practice is part of the Northwestern Medicine Physician Network.
Questions Patients Often Ask
Is Laser Hair Removal Completely Safe?
No. There are always risks with any laser treatment. However, if you follow all the instructions for how to prepare and what to do after each treatment, the risks are lower.
Refer to the sections above for how careful treatment and your own care lower them, and what they are.
Is Hair Gone Forever After Laser Hair Removal?
Not necessarily. You can have long term hair reduction with laser hair removal. However, some hair may grow back in the treated area.
If this occurs we may recommend maintenance treatments based on how your hair responds to the initial series of treatments.
Can I Shave Right Before My Session?
It varies. You should shave prior to your treatment, but when you shave will depend on your treatment schedule. Please refer to the instructions above.
Please let us know if you nick yourself or have irritation from the razor in the area you are having treated.
Is Laser Hair Removal Safe for Darker Skin Tones?
Yes. Please refer to the section above on skin tone for how we safely treat darker skin tones. That means the laser, settings and cooling are chosen for your skin.
Is Laser Hair Removal Bad for Your Skin Over Time?
Not necessarily. Based on what we know from research to date, it has not been shown to cause cancer. Please refer to the section above on complications you should be aware of before booking an appointment for laser hair removal to see what long term changes may occur with laser hair removal.
Talk With Us About Your Next Step
If you have additional questions about your options or would like to schedule an appointment, please contact us or request an appointment here.
Individual results and duration of results may vary. Outcomes are not guaranteed.
