Are there any negative side effects of the pain killer Fioricet?

Are there any negative side effects of the pain killer Fioricet?
My doctor prescribed Fioricet to me for my migraines. My Rx says that I can take 2 pills – 4 times a day. Are there any known long term side effects from using this drug? I take them pretty regularly.

There are losts of good answers, but the best answer:

Answer by Comrade Demitri Dingleberry
Plague and genital rats.

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