What if you took 90 mg of Adderall?

I think you mean milli (0.001) grams not mega (1000000) grams. 60 milli grams per day is the max dosage. Overdose may cause:

* Hyperactivity (trouble sitting still) * Rapid breathing * Confusion * Seizures * Fever * Muscle pains * Shakiness * Aggressiveness * Hallucinations * Death

Don't take anymore than your doctor prescribes. Don't ever take more than 60mg. A dosage of more than 60mg will not be pleasant!!! PS I'm not a doctor so double check with a doctor all my fact and figures before acting on them!!!