Yeah. It is pretty safe if you are referring to the sweat glands. Actually the Lasers target the hairs which are black and you must be knowing the physic principle that black things absorb heat rapids. The modern lasers and I.P.L. machines work on this principal and the melanin pigment; which is black; present in hairs absorbs the rays and gets heated and destroyed. there is a caution though that the rays should not be used more than six times in a 2 years periods and it slightly increases the incidence of skin cancer. The change is sweat smell and quantity you are referring could be because of weather, washing habits, use of perfumes and weather changes.