Serious tizanidine and alcohol interactions can occur if taken together.
Drinking alcohol while taking tizanidine can lead to an increase in side effects from the drug, including dizziness, drowsiness, and low blood pressure. It can increase the risk of falls, as well (due to increased risk of dizziness).
Drinking alcohol interferes with the way the body utilizes tizanidine, increasing the amount of it in the system. That, in turn, leads to an increase in the side effects.