Brother abusing stimulants (adderall (dextroamphetamine and racemic amphetamine) and ephedrine).. how high does his heart rate need to get before we have to bring him to the hospital (where it is life threatening)?

Call poison control: It depends on what else he is taking & amounts. Time for a family intervention for treatment for abuse. Tough situation! Families of drug and/or alcohol abusers can be part of a solution or part of the problem. Get educated as to your role & be part of the solution. See http://tinyurl.com/nv47auh

It depends: different patients can tolerate varying speeds of heart rate for different amount of times. Sustained tachycardia may turn into a fatal rhythm - there is no cut off point for heart rate but generally any chest pain or sustained high heart rate needs an evaluation. Have your brother see a doctor about his drug abuse asap.

Adderall (dextroamphetamine and racemic amphetamine) Abuse: There is not an actual limit to heart rate which would necessitate your brother going to the ER. The next time he abuses stimulants, he could die. As such, he needs help now, right away. Your brother needs to become part of a program to get off drugs. He will need family support, but you cannot do this for him. He needs to do much of this himself. It is after all,, his problem. Good luck.

Sorry to hear this: First of all, I am sorry to hear about this. Unfortunately there is no one right answer to this. More than the heart rate rise (which in young people is generally well tolerated), I would be concerned about the blood pressure. If the systolic blood pressure is above 180-200 mmHg, that's concerning enough to bring your brother to the hospital. Of course, addiction therapy is far more important.

There is no magic #: young and otherwise healthy people can tolerate very high heart rates. What is needed is a family meeting to look at ways of getting him help for his drug problem. I assume people have tried and failed at this already. A formal intervention with a family therapist can sometimes be very helpful. As long as he isn't lightheaded or short of breath, tachycardia is not harmful.

Get Help: Pulse rates over 200 per minute for a 20 year old and 150 beats per a person 70 years are dangerous. But the point here is that an intervention must occur before such dangerous problems occur. He is abusing drugs and need a professional evaluation by experts in drug abuse to recommend how he can beast be helped. No time to wait.