"My current dose of Adderall is less effective than it had been when I started. What's going on?"
by Larry Silver, M.D.
I'm glad you are thinking and taking responsibility for your ADHD needs.
The dose of Adderall needed is not based on age or body weight. It appears to be based on the specific pattern of metabolizing the medication for each person. Thus, some need 5 mg per dose, some 10, some 15, and some 20. Each individual needs to find out.
When you say that you use to take 20 mg a day, did you mean 10 mg twice a day? If so, you may find that you now need a higher dose, perhaps 15 or 20 mg each dose. Each dose lasts between four and five hours. So, experiment with when you need coverage. Perhaps you can take it during classes, skip time in the late afternoon when you are "vegging" out, then take a dose to cover homework. Discuss these options with your physician.