Does one laser treatment permanently remove hair?

One session of laser hair removal will permanently remove SOME hairs in a specific area, but definitely not all of them. If it just took a single treatment people would be quite happy! The hairs on your hair have a long growth cycle, so it will take them quite awhile to come back in this area - 6-12 months to see growth. If you want to make it happen faster, you could try Latisse. This would be off-label use for this product but what it does is make the growth cycle much faster for areas where it's applied, so those hairs where you were accidentally treated will start growing back at a faster rate. "This answer has been solicited without seeing this patient and cannot
be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."