Get emergency medical help if you have any of these signs of an allergic reaction to Xanax XR: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have any of these serious side effects:
unusual risk-taking behavior, decreased inhibitions, no fear of danger;
depressed mood, thoughts of suicide or hurting yourself;
hyperactivity, agitation, hostility, hallucinations;
feeling light-headed, fainting;
seizure (convulsions);
urinating less than usual or not at all;
muscle twitching, tremor; or
jaundice (yellowing of the skin or eyes).
Less serious Xanax XR side effects may include:
drowsiness, dizziness, feeling irritable;
amnesia or forgetfulness, trouble concentrating;
sleep problems (insomnia);
muscle weakness, lack of balance or coordination, slurred speech;
blurred vision;
nausea, vomiting, constipation, appetite or weight changes;
dry or watery mouth, increased sweating; or
loss of interest in sex.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Xanax XR side effects (more detail)
