Paradoxical regrowth or hypertrichosis: a side effect of laser hair removal

During laser hair removal, the light beam is applied to an area and, more broadly, heats up the follicles adjacent to the targeted hair. This can lead to hair growth.

This is called paradoxical regrowth or paradoxical hypertrichosis.

Does paradoxical regrowth occur because of the laser?

This side effect is not specific to laser hair removal: it can also occur after any type of hair removal (waxing, IPL, tweezing) or even after shaving. However, its appearance during a laser treatment is particularly noticeable and annoying: it risks prolonging an already time-consuming and costly treatment.

Is paradoxical regrowth serious?

No, it simply means that the treatment area has to be extended a little.
Is paradoxical hypertrichosis frequent?

Paradoxical hypertrichosis occurs in 0.6 to 10% of cases. It occurs most often on the face and neck.

What causes paradoxical hypertrichosis ?

Paradoxical hypertrichosis can be caused by the effect of inflammatory mediators and sub-perapeutic thermal damage inducing the start of the hair cycle (source)

What factors influence paradoxical regrowth?

Paradoxical regrowth can be promoted by several variables:

  • Failure to follow the precautions of use.
  • Hormonal imbalances.
  • Treatment of certain areas that are particularly sensitive to hormones, such as the upper back and shoulders for men or the lower jaw and areola area for women.
  • Removal of “sensitive” hair: very fine hair or hair surrounded by down.
  • A poorly adjusted laser (too weak or too strong).
  • Having dark skin (types III, IV, V and VI)