Kevin,

My thought is the fentanyl, nausea and flu like symptoms are common side effects. I experienced vomiting while on it myself (was on fentanyl for 18 months)...understanding that the fentanyl patch is inconsistent in delivering the medication in proper doses due to the delivery system being body heat activated.

What would happen to me is that I would try to be too active, raise my body temp allowing more fentanyl to be released then normal...once the fentanyl made it into my blood stream (several hours later) I would have different issues, vomitting, dizziness, respitory are among them...it actually put me into the ER on a few occasions.

I would suspect when your husband feels good, he gets more active, raises his body temp...and then feels the effects of the fentanyl after it makes it's way into his bloodsteam. Hope it helps

Eric