First, you don't say if this is being done with a psychiatrist or just a regular doc. The former will know more about the drugs, at least theoretically. I'm also not sure why you're starting two drugs at the same time. I'm not sure why I was originally started on two drugs at the same time, either, many years ago. Why take two if only one will do? But these are very different drugs and I don't think serotonin syndrome is a serious issue, though talking it through with your psychiatrist isn't a bad idea. Buspar does not have a very good track record or clinical success in research studies, but it is thought to have a mild effect on serotonin. Doxepin is a tricyclic antidepressant, which also doesn't have the kind of very strong effect on serotonin receptors that, say, ssris and snris do. Serotonin syndrome is very rare, but again, if you have any concerns, discuss them with your psychiatrist. Usually these days, buspar's only use that is thought to have a sizable effect is to augment an antidepressant, usually an ssri, and I don't think it would be used that way if serotonin syndrome was a big issue with it. The doxepin is more likely to help, so if you want to just take one and you have decided to take medication instead of try therapy, and I have no idea how severe your life is being disrupted, that's probably the one to try. But it's your choice. Discuss it with your psychiatrist and then make your informed choice.