Can an Adderall (dextroamphetamine and racemic amphetamine) overdose be fatal?

Expect so. Overdose of adderall (dextroamphetamine and racemic amphetamine) can trigger a cardiac arrhythmia. I hope you are taking it under a doctor's supervision. Speak to your doctor. Do not try to regulate the dose on your own.
Adderall (dextroamphetamine and racemic amphetamine) Depends on dose ingested & your cardiovascular health.
Unlikely. Adderall (dextroamphetamine and racemic amphetamine) (amphetamine) overdose can cause psychotic symptoms, chest pain, palpitations, increase heart rate and blood pressure, but it would be unlikely to be fatal.