The short answer
If laser seems not to be working, the usual reasons are too few sessions so far, hair that is too light or grey, settings that are too low, or a hormonal driver such as PCOS. Results also build gradually because only follicles in their active growth phase respond. Rarely, paradoxical hypertrichosis (increased growth) can occur. Review the cause with your practitioner rather than simply paying for more of the same.
It is frustrating to invest in laser and feel the hair is still there. Often the explanation is straightforward and fixable — expectations, timing or settings — rather than the treatment failing outright. This page works through the common reasons in order, so you can have an informed conversation with your clinic.
Common reasons at a glance
- Too early Results build over several sessions
- Hair colour Light/grey hair responds poorly
- Settings May be set too low
- Hormones PCOS and others drive regrowth
- Spacing Sessions mistimed for growth cycle
- Rare Paradoxical hypertrichosis
It may be too early
The most common reason is simply that not enough sessions have happened yet. Laser only meaningfully affects follicles in their active (anagen) growth phase, and only a share of your follicles are in that phase at any time. That is why a course is six to eight sessions, spaced four to eight weeks apart — to catch successive waves of hair. After one or two sessions, plenty of hair will still appear, and shed hairs working their way out can look like regrowth. Judge progress over the whole course, not the first session. See how many sessions you need.
Your hair or skin may not be ideal
Laser targets melanin, so dark, coarse hair responds best. If your hair is blonde, red, grey or white, it has little pigment and will respond poorly — sometimes barely at all. A patch test should have flagged this, but mixed-colour areas can leave the lighter hairs untouched. Equally, the device and settings must suit your skin tone; the wrong combination can be ineffective (or unsafe) on different skin tones.
Settings, technique or device
If the energy (fluence) is set too low — sometimes to prioritise comfort, or out of caution on a particular skin tone — the laser may not heat follicles enough to disable them. There is a genuine balance here, because settings that are too aggressive risk burns and pigment changes, while settings that are too gentle achieve little; an experienced practitioner finds the safe, effective middle ground for your skin and hair. Practitioner skill matters in other ways too: coverage gaps that leave patches untreated, the wrong device for your hair and skin combination, or an inappropriate spot size can all blunt results even when everything else is right. This is one of the strongest arguments for choosing a qualified, experienced clinic rather than the cheapest option.
| Possible cause | What to do |
|---|---|
| Too few sessions | Complete the course before judging |
| Light or grey hair | Reassess suitability; consider electrolysis |
| Settings too low | Ask the practitioner to review fluence safely |
| Mistimed sessions | Keep to the recommended spacing |
| Hormonal driver | See a GP about PCOS or other causes |
Hormones and the rare paradox
Hormone-driven growth — most commonly PCOS — keeps stimulating follicles, so hair can return between or after sessions despite good treatment. This is a frequent reason facial and body hair seems not to clear. Rarely, some people experience paradoxical hypertrichosis: increased rather than reduced hair growth, usually at the edges of treated areas, more often reported on the face and neck and in certain skin and hair types. It is uncommon, but if you notice more hair rather than less, raise it with your practitioner.
What to do next
- Confirm how many sessions you have actually had and whether the course is complete.
- Ask the practitioner to review device choice and settings for your hair and skin.
- If hair is light or grey, discuss electrolysis instead.
- If growth is hormonal or sudden, see a GP.
It also helps to check what you are doing between sessions. Waxing, threading or plucking removes the hair root that the laser needs to target, so relying on those methods mid-course can quietly undermine the whole treatment — shaving only is the rule. Recent sun exposure or self-tan can force the practitioner to lower the settings for safety, which also reduces effectiveness. Putting these controllable factors right often makes more difference than simply booking further sessions.
Remember the realistic target throughout: long-term reduction, not guaranteed permanent removal of every hair. A degree of remaining or returning hair does not mean the treatment has failed. This page is general information, not medical advice; a qualified practitioner should review your individual case, and results vary between people.
Get a proper review of your results
If laser seems not to be working, an honest clinic will review the likely cause before recommending more sessions. Find a practitioner who offers a thorough reassessment.
Frequently asked questions
How do I know if laser is actually working?
Judge over the whole course, not the first session. Density should drop after the second or third session, with finer, sparser regrowth. If there is no change by mid-course, ask for a review.
Can settings being too low stop it working?
Yes. If the energy is set too low — sometimes for comfort — follicles may not be heated enough. Ask the practitioner to review the settings safely for your skin and hair.
Why is my hair growing back between sessions?
Some regrowth between sessions is normal because of the hair-growth cycle. Persistent regrowth can point to a hormonal driver such as PCOS, which is worth raising with a GP.
Can laser cause more hair to grow?
Rarely, paradoxical hypertrichosis can cause increased growth, usually at the edges of treated areas and more often on the face or neck. Tell your practitioner if you notice more hair.
Sources & further reading
- NHS — Cosmetic procedures: laser hair removal and IPL
- NHS — Excessive hair growth (hirsutism)
- MHRA — Lasers and IPL for cosmetic use: safety guidance
- British Medical Laser Association — Laser hair removal practice standards
This guide is general information, not medical advice. A patch test and consultation with a qualified, regulated practitioner are essential before treatment, and results vary by individual. Laser achieves long-term hair reduction, not guaranteed permanent removal of every hair. Discuss any skin or health concerns with the practitioner or your GP.