What will happen if you combine adderall, (dextroamphetamine and racemic amphetamine) caffeine, & yohimbine?

Not good!: Bad combination to combine all 3 together. Discuss this with your doctor first. It's possible playing with a disaster in the making as each drug alone has a high side effect profile, and caffeine in itself acts like a drug. Would not advise doing it.

Get really nervous: In combination these are likey to make you quite nervous and can lead to panicy states.