I have been prescribed adderall, (dextroamphetamine and racemic amphetamine) and have been experiencing a reoccurring painless muscle spasm/twitch under my left breast. what can this be?

Fasiculation: It may be a benign muscle twitch or fasiculation. May or may not be related to the adderall (dextroamphetamine and racemic amphetamine).. Try not taking it over the weekend and if it goes away and then comes back when you restart the med, then you have your answer...(and you may need to change ADD/ADHD meds if it is annoying you).

Possible side effect: It could be that the twitching is a side effect of the Adderal or it could be from something else. Did it ever happen before? Time to speak with your doctor