It is recommended to delay the use of tretinoin, Retin A, Renova, Differin, Tazorac, Avage, Epiduo, Ziana and high percentage AHA and BHA products for approximately five days prior to treatment. Consult your physician before temporarily discontinuing use of any prescription medications. Hair must be a minimum of 1/4 inch long and preferably no longer than 1/2 for your comfort.