I have sciatica and have been literally sitting on a heating pad for hours at a time. could this be making the pain worse?

Probably not: You would want to make sure you are not using the heating pad to the extent it is causing a burn or other soft tissue injury to the area. In general, topical heat or cold are ok to try, but usually don't have too much affect on patients with sciatica. This is because the root of the problem is deep in the spine at the level of the nerve roots, and tooicL heat or cold does not change core temp

No, but watch burns: Sciatica can be treated. If your heat pad doesn't resolve this (likely) see a pain or PMR doc for,work up of cause. Then treatments including home stretching. Prolonged use of high heat can burn tissues, causing them to discolor. This should be avoided. I n reality the sciatic nerve is over 5 inches deep, and the heat just doesn't get down that far