Why Is Hair Growing Back 1 Week After First Hair Removal Treatment?

Doctor Answers 4

Hair Regrowth After Laser Hair Removal Treatment

Many patients wonder why they experience hair regrowth after their laser treatment. 

Laser hair removal permanently reduces the number of hairs. Only hairs that are in the active growth phase (ANAGEN) respond most effectively to laser treatment. Also because dark hairs contain more melanin, these would also respond better to lasers compared to light hairs. Melanin is necessary to absorb the laser light so that it can affect the follicle. .

Since up to half of the hair at any given time can be in the resting phase (TELOGEN), almost half of the hair would not respond.

That is why serial and multiple treatments are necessary. Also, hair growth cycles are different for different patients. This is usually governed by genetics.

Redondo Beach Dermatologic Surgeon
4.6 out of 5 stars 32 reviews

What to expect from Laser hair removal treatment

With multiple Laser hair removal treatments, significant long-term reduction can be achieved. In general, two or more treatments are required at each site. The laser is only effective when the hair follicle is in its active growth phase. Repeat sessions will be necessary to treat those follicles when they re-enter the growth phase. Approximately 15-30% long-term hair loss may be observed with each treatment when optimal parameters are used. Optimal long-term benefits depend on the area you wish to have treated, the hair density, and your hair’s growth cycle. Darker hair responds best to the laser, while lighter hair is less responsive.


Mitchell Schwartz, MD
South Burlington Dermatologic Surgeon
4.7 out of 5 stars 12 reviews

Laser Hair Removal Treatment

Laser hair removal targets the hair follicle in certain phases of hair growth.  So the growth you are seeing is most likely hair that was not targeted by the laser at this time.  Multiple sessions are requires for most people to get the best results.

Sheri G. Feldman, MD
Beverly Hills Dermatologist
5.0 out of 5 stars 1 review

Laser Hair Removal

New hair is still growing, especially after only one laser session.  In order to have optimal results when using laser hair removal, you should have several treatments at set intervals.  The laser focuses on hair that is in the active growth cycle.  Having treatments scheduled at set intervals ensures that the majority of hair follicles will be eliminated.

Michele S. Green, MD
New York Dermatologist
5.0 out of 5 stars 76 reviews

These answers are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.