Lots of bad info on net. Always horror stories......Valium is good muscle relaxant, but it has components that stay active up to a week. In a sense, your dose self increases the first week, so tapering is a bit harder than some medications. Still from 5 mg, you should be able to cut to 2.5 for a couple weeks then either quit or cut again to 1mg (split a 2mg) for a while. 18 months is ridiculous. A month is a long taper schedule for Valium. The last dose may be toughest. I would try your doctors recommendations for taper, then let her know if any problems. Sometimes just a small dose for extra couple days can make a helpful difference.