Is uncontrollable muscle movements a side effect of neurontin (gabapentin) if so how serious is it?

Yes: Uncontrollable muscle movements can occur either as dyskinetic movements or as choreoathetosis. Symptoms such as these include abnormal muscle movements of the face arms trunk or even the diaphragm and choreoathetosis would be large flailing movements of the extremities. For these movements tend to continue until the medication is stopped. Have your prescribing physician discuss with you how to taper the Neurontin (gabapentin) in order to avoid withdrawal.Best wishes.