Laser hair removal gone wrong: signs, causes and what can help

What can go wrong after laser hair removal?

Most laser hair removal sessions go smoothly, and the expected reaction is short-lived: redness and small raised bumps around the hair follicles that usually settle within hours. When something goes wrong, the usual problems are burns or blisters, darker or lighter patches of skin, and, less often, new hair growth near the treated area.

Laser hair removal works by sending light into the hair, where the pigment absorbs it and turns it into heat that damages the follicle. The same pigment exists in the surrounding skin, so the challenge is to heat the hair without overheating the skin. Problems usually come from:

• Skin with more pigment at the time of treatment, especially a fresh tan, recent sun or self-tanner.
• A wavelength or energy that does not suit the skin tone, or too little cooling.
• Light-sensitising medicines or recent oral acne medicine.
• Treating over moles, tattoos or darker patches that absorb more energy.
• Aftercare problems, such as heat, friction or sun soon after a session.

Other problems include folliculitis, itching or hives, cold sore flares on the upper lip, and, rarely, scarring or eye injury. Some disappointments are not complications at all: grey, white, blonde and very fine hair responds poorly because it has too little pigment.

The sections below explain each problem, how to tell it from normal healing and when to see a doctor. For how the treatment is done at SkinRev Lab, see the main laser hair removal page.

How common are laser hair removal complications?

Serious complications after laser hair removal are uncommon, and most side effects are minor and short-lived, although the risk rises with tanned skin, unsuitable settings and inexperienced operators.

• The American Academy of Dermatology describes discomfort, swelling and redness lasting one to three days as the common side effects. Blistering, changes in skin colour, scarring, infection and cold sore outbreaks are listed as other possible side effects, and burns, lasting colour changes and scars are described as risks in inexperienced hands.
• A 2021 systematic review and meta-analysis of paradoxical hair growth after laser and light hair removal, pooling 22 studies, measured a rate of about 3%. It was linked to treatment of the face and neck and was very uncommon elsewhere (Snast and colleagues, 2021).
• A case report and literature review of laser hair removal without medical supervision described burns, darker patches, slight scarring and other effects, and noted that side effects were more common when untrained staff performed the treatment (Vano-Galvan and Jaen, 2009).

Two practical points follow. First, most people complete a course with nothing more than brief redness and bumps. Second, the person performing the laser, the wavelength chosen for the skin tone and the state of the skin on the day make a large difference to the risk. Your doctor will advise how this applies to your skin and hair.

Burns and blisters after laser hair removal

A laser hair removal burn shows as pain, redness and swelling that are stronger than usual, often followed by blisters or crusting, and it needs a doctor's review within a day. Burns can appear during the session or develop over the following hours, so a mark that looks worse that evening is worth taking seriously.

Signs that point to a burn:

• Pain during the session that is noticeably worse than in earlier sessions.
• A burning sensation, with redness and puffiness lasting beyond a day.
• Blisters, raw patches or crusts.
• Marks in the shape or pattern of the treatment tip, such as squares or stripes.

Common causes: treating tanned or sunburnt skin, self-tanner on the area, energy too high for the skin tone, a wavelength that does not suit darker skin, too little cooling, overlapping pulses, or light-sensitising medicines.

What to do now: apply a cool compress for about ten minutes at a time, keep the area clean, do not pop blisters or pick crusts, avoid friction from tight clothing, and keep the area out of the sun. Contact the provider who performed the treatment, or see a doctor, for a wound check. Blisters need a doctor's care rather than home care alone, and a doctor can advise on ointments or dressings.

Why it matters: burns can leave darker or lighter marks once they heal, and blistered or infected burns can occasionally scar. Early care lowers these risks. Further sessions on the area wait until it has fully healed and the cause has been identified.

Darker or lighter skin after laser hair removal

Darker or lighter patches after laser hair removal are usually temporary, and they are more likely in tanned or darker skin; most fade over months with sun protection and a pause from treatment on the area. Darker patches are post-inflammatory hyperpigmentation (PIH), where pigment cells react to heat. Lighter patches (hypopigmentation) happen when pigment cells are suppressed, often after a burn or treatment over a tan.

What raises the risk:

• A tan, sunburn or self-tanner at the time of treatment.
• A wavelength or energy level that does not suit the skin tone.
• Skin that marks easily after bites, acne or friction, such as underarms and bikini line.
• Burns or blisters during the course.

What usually helps:

• Daily sunscreen on exposed areas and staying out of strong sun.
• Pausing laser on the affected area until the colour has settled.
• Gentle skincare with no scrubs or acids on the area.
• For darker patches, a prescription lightening cream where your doctor advises.
• For lighter patches, time and even sun protection, which helps keep the contrast from widening.

The American Academy of Dermatology notes that skin colour usually returns to normal over time, although some changes last. When treatment restarts, the doctor may change wavelength or settings; longer wavelengths such as 1064 nm are usually chosen for tanned or darker skin. For more on treating darker skin, see laser hair removal for dark skin.

More hair after laser: paradoxical hair growth

Paradoxical hair growth is when fine hair near or within a treated area becomes thicker or darker after laser, and it is uncommon, mainly affects the face and neck, and often improves with continued treatment. A 2021 meta-analysis measured a pooled rate of about 3%, linked to treatment of the face and neck (Snast and colleagues, 2021).

It tends to appear along the edges of treated areas, such as the jawline, upper neck, cheeks or sides of the face. The cause is not fully understood. One theory is that heat below the level needed to disable a follicle can stimulate nearby fine hairs instead.

It is worth separating from three normal events:

• Shedding: treated hairs push out over one to three weeks, which can look like regrowth.
• New growth cycles: follicles that were resting during a session start growing later, which is why a course is needed.
• Hormonal hair growth: conditions such as PCOS can drive new hair growth and may need a medical review of the hormone side.

What usually helps: the meta-analysis found that the type of device and the gap between sessions did not change the rate, and three of the four studies that tracked it found that paradoxical growth gradually improved with continued treatment. A doctor may adjust settings, cooling and the treatment area so the edges are covered. If hormones may be involved, a medical review comes first; see PCOS hair removal.

Bumps, folliculitis and itching

Small raised bumps around the hairs straight after laser are expected and usually settle within hours; spots or pustules that appear over the next few days are usually folliculitis, which tends to settle with simple care. Folliculitis is inflammation of the hair follicles, often triggered by heat, sweat, friction or shaving on freshly treated skin.

What you may notice:

• Red or white-headed spots centred on hairs, often on the legs, bikini line or underarms.
• Itching or raised, hive-like patches for a few hours after a session.
• Ingrown hairs as treated hairs shed.
• Cold sores on the upper lip in people who get them.

What usually helps:

• Cool compresses and an unperfumed moisturiser in the first 48 hours.
• No hot showers, saunas, gym sessions or perfumed products for the rest of the day.
• No scrubs, acids or alcohol-based deodorant for two to three days.
• Loose clothing over the area, and clean razors when shaving between sessions.

Spots that spread, become painful, or keep returning should be reviewed by a doctor, who can decide whether a prescription treatment is needed. Let the doctor know before the next session if you get cold sores, as a plan may be needed when treating the upper lip. For more on these conditions, see folliculitis and ingrown hair.

Eye injury, scarring and other rare problems

Eye injury and scarring after laser hair removal are rare, but eye symptoms during or after a session need urgent care, and scarring is most often linked to burns that blistered or became infected. Laser light can damage the eye, which is why everyone in the room wears eye protection.

Eye symptoms that need urgent eye care immediately:

• Eye pain, or sensitivity to light that does not settle.
• Blurred vision, a dark spot, flashes or new floaters.

Treatment close to the eyes needs particular care, and areas inside the bony rim of the eye socket are generally not treated.

Scarring: uncommon. It usually follows a burn that blistered deeply, was picked or became infected. Early wound care lowers the risk. If a scar forms, it is reviewed once healing is complete, and options are chosen case by case.

Moles and tattoos: both absorb laser energy strongly. They are shielded or avoided during treatment. A tattoo treated by mistake can blister or change colour, and a mole that changes after laser, or at any time, should be examined by a doctor.

Poor results: slow progress is not always a complication. Grey, white, blonde, red and very fine hair responds poorly, and hormonal hair growth may need medical review. A course usually takes several months, with sessions spaced about four to eight weeks apart. For what to expect from a course, see laser hair removal sessions.

Warning signs: what is normal and when to get help

Redness and small bumps around the hairs for a few hours to a day are normal after laser hair removal; blisters, crusting, dark or light patches and any eye symptoms are not. Use the table as a general guide, and contact your provider or a doctor if you are unsure.

For the usual sensations and aftercare in more detail, see laser hair removal pain and aftercare.

How Dr Sin Yong assesses and corrects laser hair removal problems

At SkinRev Lab, Dr Sin Yong, medical adviser, assesses laser hair removal problems by examining the skin and hair, identifying the type of problem and reviewing how the treatment was done before deciding on next steps. Often the first step is to let the skin heal and settle before any further laser.

What helps the assessment:

• The dates of your sessions and the areas treated.
• The device and wavelength used, if you know them, and whether a test patch was done.
• Any tan, self-tanner or medicines around the time of treatment.
• Photos of the problem as it developed.

What correction may involve, where appropriate:

• Burn care, dressings and treatment of any infection.
• A sun-protection and prescription plan for darker patches.
• Time and review for lighter patches.
• For paradoxical hair growth, a plan to continue treatment over the affected area with adjusted settings and cooling.
• When treatment resumes, the Lutronic Clarity II used at SkinRev Lab offers 755 nm alexandrite and 1064 nm Nd:YAG, so the wavelength can be chosen for your skin tone, area by area, and a small test area may be done first if your skin is darker or sensitive.

Improvement takes time, and some changes may only partly improve. Dr Sin Yong will explain what is realistic, and correction is priced at consultation. If your treatment was done elsewhere, it is still worth contacting that provider too, as they hold your treatment records.

How to lower the risk: questions to ask before laser hair removal

The most useful way to lower the risk is to choose a provider who checks your skin tone, hair and medical history first, chooses a wavelength that suits your skin, and gives clear preparation and aftercare instructions. These questions help:

• Who performs the laser, and is a doctor involved in assessing my skin?
• Which device and wavelength will be used, and why does it suit my skin tone?
• Will a test area be done first, especially if my skin is darker or sensitive, or I have had recent sun?
• How is the skin cooled during treatment?
• How many sessions and how far apart, and what happens if hair grows back thicker?
• Who do I contact if I get blisters, crusting or a dark or light patch?

Preparation that lowers the risk:

• Four weeks before: stop waxing, plucking, threading and epilating. Shaving is fine.
• Two weeks before: avoid tanning and strong sun.
• One week before: stop retinoids, exfoliating acids and self-tanner on the area.
• The day before: shave the area closely.
• On the day: arrive with clean, dry skin and no deodorant, lotion or make-up on the area.

Tell the doctor about: pregnancy, recent oral acne medicine, light-sensitising medicines, cold sores, and any moles or tattoos in the area. For costs, see laser hair removal price.