Although there is no problem with having laser hair removal while on Tamoxifen, there is a rare risk of complications with laser hair removal without chemotherapy. Blisters and secondary infections, including herpes simplex reactivation, and should a complication occur while you are on Tamoxifen, would you heal as well or could the infection progress more? Furthermore, if there is any side effect such as thinning hair while on Tamoxifen, then the laser hair removal might not work as effectively compared with doing it once your hair returns to a normal growth after the Tamoxifen is completed. Check with your oncologist.
Web reference: http://www.thenyac.com/laser-hair-removal/index.html