May 21, - I've taken Xanax for a number of years and the strongest are the bars which equal 2mg. I don't know anything about the extended release Xanax as my doctor, Are 2 mg of green Xanax stronger than the 2mg of. color,shape,size,mg,and picture from strongest to the weakest at least most Xanax pills (I didn't include any of the generic tablets): Xanax XR. Learn about Xanax (Alprazolam) may treat, uses, dosage, side effects, drug interactions, warnings, patient labeling, reviews, and related medications. Read All Potential Side Effects and See Pictures of Xanax» .. The risk of seizure seems to be greatest 24–72 hours after discontinuation .. Alprazolam XR 2 mg-BAR.