Is laser hair removal dangerous? Side effects, risks and myths

The short answer

• Common and temporary: redness, slight swelling and a feeling of warmth for a few hours to a few days
• Rare: blisters, crusts, temporary changes in pigmentation
• Very rare: scars or lasting pigment changes, mainly with incorrect settings
• Paradoxical hypertrichosis (more hair instead of less): rare on the face and neck, very rare on the rest of the body
• Eyes: at risk without protection, which is why protective goggles are mandatory
• Cancer: laser hair removal works with non-ionising radiation; the risk lies elsewhere – with moles that are lasered

What's normal after a session

Right after the treatment, the skin is usually red and slightly swollen, and it often feels warm, as if you'd had a little too much sun. This is the expected reaction to the heat that is meant to reach the hair root, and it subsides within a few hours to two days. Cooling helps, as does a soothing moisturiser with panthenol. What you should avoid in the days afterwards is explained under Preparation and aftercare.

Rare side effects

Less often, blisters or crusts form, or the skin in the treated area temporarily becomes lighter or darker. If you're prone to cold sores, you may get an outbreak after a treatment on the face; infections are also possible – the American Academy of Dermatology lists both among the rare side effects.

Very rarely, scars or lasting pigment changes remain. The German Federal Office for Radiation Protection (Bundesamt für Strahlenschutz) names excessive radiation intensity as a common cause and writes: the darker the skin, the higher the risk of unwanted side effects. That's exactly why the settings are adjusted to skin type and hair, and why particular care is taken with darker skin.

If redness or swelling lasts longer than two days, if blisters or crusts form or if the skin is unusually painful: don't wait – call the studio.

Paradoxical hypertrichosis: when more hair grows

In rare cases, the treatment has the opposite effect: at the edge of the treated area, fine hair grows back more densely than before. An analysis of 22 studies with almost 10,000 people treated found this in about 3% overall, almost exclusively on the face and neck. On the rest of the body, it is very rare, at about 0.08%. The type of device played no recognisable role, and in three out of four studies that looked at this, the increased growth improved with further sessions. It isn't possible to say for certain in advance who will be affected. That's why we talk about it openly before a treatment on the face.

Eyes: why protective goggles are mandatory

The light used for hair removal is in the range of visible light and infrared A. According to the Bundesamt für Strahlenschutz, these wavelengths reach the retina – if the radiation hits the eye, damage is possible. Eye protection is therefore mandatory during every treatment. With us, you're given protective goggles at every session. We don't treat the eyebrows or anything inside the bony rim around the eye, because a safe enough distance from the eye can't be maintained there.

The cancer myth: what's behind it

The worry comes from the word "radiation". X-rays and radioactive radiation are ionising: they carry so much energy that they can knock electrons out of atoms and molecules. According to the Bundesamt für Strahlenschutz, visible light and infrared carry less energy. Accordingly, cosmetic lasers in Germany fall under the "Ordinance on Protection against the Harmful Effects of Non-Ionising Radiation in Applications on Humans" (Verordnung zum Schutz vor schädlichen Wirkungen nichtionisierender Strahlung bei der Anwendung am Menschen, NiSV). The laser works through heat: the light is absorbed by the melanin in the hair and converted into heat. Laser hair removal doesn't use the part of optical radiation that is considered a cause of skin cancer, namely UV radiation.

There is a real risk all the same, and it concerns moles. If they are lasered as well, they can change – become lighter, shrink or look different in pattern. A 2023 review found no malignant transformation in the studies it analysed, but stresses that long-term data are lacking and that such changes can mimic suspicious moles during skin cancer screening. The Bundesamt für Strahlenschutz, for its part, warns that a skin cancer diagnosis can be made more difficult. That's why pigmented moles are always left out. Please have any conspicuous moles checked by a dermatologist beforehand.

Other myths briefly explained

• "The hair grows back thicker afterwards." Usually it's the other way round: the remaining hairs become finer and lighter. The exception is paradoxical hypertrichosis (see above).
• "Home devices are harmless because they're weaker." Their energy density is usually lower than that of studio devices, but that doesn't make them safe. The certified expertise requirement doesn't apply when you use a device on yourself – so follow the instructions for use all the more carefully, including on eye protection. More in the article At-home IPL device or treatment in a salon?
• "Dark skin can't be lasered." It can, but with more caution and a suitable wavelength. A test patch is particularly important here.

Who shouldn't have laser treatment

We don't treat in the case of:

• taking photosensitising medication (e.g. certain antibiotics, isotretinoin, St John's wort)
• light-induced skin conditions (photodermatoses) and cutaneous porphyrias
• acute skin conditions, sunburn or a fresh tan in the treatment area
• pregnancy and breastfeeding – we explain why in the article Laser hair removal during pregnancy and breastfeeding

Pigmented moles and tattoos are left out. Treating them with a laser is reserved for doctors. The Bundesamt für Strahlenschutz also names skin cancer as an example of a contraindication. If you're unsure whether any of this applies to you, have it checked by a doctor beforehand.

How to reduce the risk

• Test patch before the first session. This shows how your skin reacts to the settings before the whole area is treated.
• No fresh tan. No sunbed, no self-tanner, no intense sun on the area for four weeks beforehand. Tanned skin absorbs more light.
• Mention your medication. St John's wort can also make the skin more sensitive to light.
• Certified expertise. Since 31 December 2022, anyone in Germany who removes hair commercially for cosmetic purposes with a laser or IPL needs certified expertise (Fachkunde) under the NiSV. Feel free to ask about it.
• Take aftercare seriously. No sport and no sauna for 24 hours, sun protection on the treated area, and get in touch if anything unusual happens.

FAQ

Sources

1. Bundesamt für Strahlenschutz: Dauerhafte Haarentfernung (Epilation). bfs.de/DE/themen/opt/anwendung-medizin-wellness/epilation/epilation.html
2. Bundesamt für Strahlenschutz: Was ist ionisierende Strahlung? bfs.de/DE/themen/ion/einfuehrung/einfuehrung_node.html
3. Bundesamt für Strahlenschutz: Was ist optische Strahlung? bfs.de/DE/themen/opt/einfuehrung/einfuehrung_node.html
4. Verordnung zum Schutz vor schädlichen Wirkungen nichtionisierender Strahlung bei der Anwendung am Menschen (NiSV), §§ 1, 2 and 5. gesetze-im-internet.de/nisv
5. AWMF S2k-Leitlinie „Lasertherapie der Haut“, 2022. register.awmf.org (013-095)
6. Snast I, Kaftory R, Lapidoth M, Levi A: Paradoxical Hypertrichosis Associated with Laser and Light Therapy for Hair Removal: A Systematic Review and Meta-analysis. Am J Clin Dermatol 2021;22(5):615–624. pubmed.ncbi.nlm.nih.gov/34057666
7. Cices A, Dover JS, Labadie JG: Changes in melanocytic nevi treated with laser hair removal: A systematic review. Lasers Surg Med 2023;55(7):617–624. doi.org/10.1002/lsm.23712
8. American Academy of Dermatology: Laser hair removal – FAQs. aad.org/public/cosmetic/hair-removal/laser-hair-removal-faqs

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