It is a non-preferred medication for me. I had to try various other medications (in a specific order) and get a statement from my doctor sent to the surgeon before the insurance would cover it. Then it was at the maximum co-pay.
The reason some insurance programs don't cover Nexium is the availability of PrilosecOTC (and generic Omeprazole), which is similar to Nexium. The same is true of medications like Clarinex, which is similar to Claritin - now a generic.
Unfortunately, Nexium works better than Prilosec for some people, and the prescription dose of Nexium is quite a bit stronger than the OTC dose of Prilosec. The trade off is the cost. A 30-day supply of Nexium costs $175 while a 30-day supply of generic Omeprazole costs about $20.
If you haven't tried PrilosecOTC you should talk to your doctor about trying it first to see if it works for you, or see if the doctor can convince the insurance company to cover the Nexium.
Nexium also has magnesium. I've read posts about how folks with magnesium defficiencies may have similar symptoms to GERD/etc. Some have taken Mg suppliments and noticed improvements. Well, you can read up on it, it's fairly cheap/easy enough to try. There are various forms of Mg and taking too much, or without enough other minerals can have side effects as well.
Mine finally did, but then again my Dr kept records on every medication I took and the results and that includes OTC as well as prescription. I was never free from acid reflux longer than a day with other meds, but with Nexium I can go many weeks at a time. Even if they denied me again, tried twice I'd still feel it was worth paying for it myself, they do make me pay the highest co pay but I don't care! I have an erosive esophagus and Nexium is slowly healing some of it from my last test!