Most laser hair removal consumers think "permanent" means lasting forever. Unfortunately, that's not always the case as it's used in advertising. For instance, a permanent wave in your hair is not really permanent, and a permanent marker is not necessarily permanent.
It's difficult to assess a new hair removal method that claims to be permanent. Most people figure that after a certain amount of time, it's unlikely that a hair will ever return. That's why several people, myself included, have suggested a specific definition of "permanent." Some of these definitions seem inadequate to me. One manufacturer claims their device is permanent based on results after 9 weeks. That's ridiculous. Waxing can last that long, and it's been clinically proven temporary.
Permanent hair removal
For the purposes of hair removal, the hairfacts definition of "permanent" is being able to go a year after your final hair removal treatment without having to use another method of hair removal. Keep in mind that a year might not be long enough to determine true permanence, but most consumers would be happy to have one treatment a year.
The only method of clinically proven permanent hair removal is electrolysis. Some lasers and flash lamps have been able to achieve permanent hair reduction, as discussed below.
Long-term hair removal
Another undefined term is "long-term" hair removal. Again, it depends on what your definition of "long" is. The hairfacts definition of "long-term" is being able to go 6 months after your final treatment without having to use another method of hair removal. Your definition may vary, but I don't consider 9 weeks to be long-term. I arbitrarily decided on 6 months as a working definition, because most hair growth cycles will have completed in 6 months.
Semi-permanent hair removal
A newer term used by some hair removal marketers is "semi-permanent hair removal." This is a marketing term used in the salon industry that some salons have started using to describe laser results. In the salon industry, it means "lasting a few weeks."
Hair reduction vs. hair removal
Permanent hair removal has been established as the complete destruction of a hair follicle's ability to regenerate and grow hair.
Several lasers have demonstrated permanent hair reduction in clinical studies and are allowed to make this claim by FDA. The word "reduction" adds another term that is vaguely defined. FDA has accepted the definition of reduction as a stable reduction in the number of coarse dark hairs. Some lasers have demonstrated in clinical testing that they can reduce the size of hairs and lighten the color. In some patients, this reduction appears to be permanent.
Click the following link for more on lasers and permanent hair reduction
If you're seeking permanent hair removal, you have several imperfect options. A number of methods have been developed that use chemicals, energy of varying types, or a combination to target the areas that regulate hair growth. Permanently destroying these areas while sparing surrounding tissue is a difficult challenge. I recommend relying on a body of published, peer-reviewed scientific evidence to ensure the effectiveness of a method.
Permanent hair removal for most (only if done correctly)
Permanent hair reduction for some (primarily consumers with dark hair)
Lasting hair inhibition for many (requires continuous use)