An employer cannot discriminate against someone due to his or her disability; and the employer must make "reasonable accomodations" for the employee due to his or her disability, which could include modifications of the dress code. However, the employer does not have to allow accomodations that disrupt the workplace. So a key issue is whether the oils, etc. are causing problems for other employees. If the scent/smell of them are causing problems, the employer can probably require you to cease using them. On the other hand, if the scent/smell is not disrupting the workplace AND 1) you can document or prove your medical conditions and 2) can document or prove that these oils are a recommended or approved treatment for your conditions--i.e. you may need some medical evidence, prescription, etc.--then the employer most likely has to allow you to use them.What may be a sticking point is getting the medical testimony, evidnece, prescription, etc. that these oils are an accepted treatment--if you cannot furnish that, then the employer may not have to consider them a "reasonable accomodation" and could enforce its dress code.