Fioricet may have some side effects, some are serious side effects, some are not serious side effects.
The serious fioricet side effects are:
an allergic reaction including difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives; or slow, weak breathing; liver damage (yellowing of the skin or eyes, nausea, abdominal pain or discomfort, unusual bleeding or bruising, severe fatigue); blood problems (easy or unusual bleeding or bruising); or low blood sugar (fatigue, increased hunger or thirst, dizziness, or fainting)
If you experience above side effects, stop taking fioricet immediately.