Erythema is an irritation and visible redness of the skin caused by increased blood flow in superficial capillaries. It can be caused by anything, from a massage or blushing to something more serious like an allergic reaction or mercury toxicity. Anything that will cause the capillaries to dilate will cause this kind of redness to appear.

There are several hair removal methods that might cause erythema, including tweezing, waxing, and laser hair removal. It is not something that is a concern—it’s a normal reaction to most skin treatments. In addition to redness, there may be swelling of the hair follicle. This is also a sign of erythema and should be considered perfectly normal. These symptoms typically only last a few hours, specifically between 12 and 24 hours after a laser hair removal treatment.

Some common yet temporary side effects of laser hair removal include:

  • Tingling or numbness
  • Itching around the treated area
  • Redness and slight irritation
  • Swelling around the hair follicle

Other side effects, which are less common may be a sign of misuse of a laser, include:

  • Bruising of the treated area
  • Temporary hyperpigmentation, or change in the pigment of the skin
  • Purpura, or a purple undertone of the skin
  • Scab formation around the treated area

Knowing which side effects to expect and which should be considered warning sides of unprofessional use is important. Most laser hair removal side effects can be treated with a cool compress and some moisturizer.