For how long the laser hair removal treatments remain effective? 

Laser treatment lasts for a longer period, but multiple sessions are needed. Laser rays are effective when hairs are in growth phase (Anagen Phase). Hairs cannot remain in anagen phase at one single time. There will be some hairs which will grow after the first session. To remove these hairs, additional sessions are required.

Laser treatment sessions depend on the skin area to be treated. For instance, back, chest and leg area will require more sessions than upper lip and chin area.

Mostly laser removal sessions lasts up to 5 treatments. In some cases such as light hair color people and dark skin people the sessions can last up to 8 weeks. But one laser session is enough to give satisfying results. Regrown hairs are thinner and lighter than previous one.