Least Effective Doses of Stimulants for ADHD
There is no "least effective dose" threshold established in clinical guidelines—rather, stimulant dosing should begin at the lowest starting dose and titrate upward until therapeutic response is achieved, as subtherapeutic dosing simply represents inadequate treatment. 1, 2
Starting Doses (Not "Least Effective" but Initial Titration Points)
Methylphenidate
- Immediate-release: Start at 5 mg twice daily (before breakfast and lunch) in pediatric patients, with increases of 5-10 mg weekly 3
- Adults: 5-20 mg three times daily, with average dosing of 20-30 mg daily 2, 3
- Maximum recommended daily dose is 60 mg 3
Amphetamine/Dextroamphetamine (Adderall)
- Starting dose: 5 mg in the morning for adults, titrating by 5 mg weekly 2
- Typical maintenance: 10-50 mg total daily dose for adults 2
- Dextroamphetamine alone: 5 mg three times daily to 20 mg twice daily 2
- Maximum doses reach 40 mg for amphetamine salts, though some patients may require up to 0.9 mg/kg or 65 mg total daily with clear documentation 2
Lisdexamfetamine (Vyvanse)
- Starting dose: 20-30 mg once daily in the morning 2, 4
- Titration: Increase by 10-20 mg weekly 2
- Maximum dose is 70 mg daily 2
Modafinil
- Mean optimum dose in adults with ADHD: 206.8 mg/day ± 84.9 mg in research studies 5
- Modafinil is not FDA-approved for ADHD and represents an off-label alternative when conventional stimulants fail 5, 6
Critical Dosing Principles
Stimulants demonstrate dose-dependent responses, meaning doses below the therapeutic threshold will not produce adequate symptom control. 7, 8 The concept of a "least effective dose" is clinically meaningless—what matters is finding each patient's optimal dose through systematic titration 2, 4.
Recommended Upper Limits
- Methylphenidate: 1 mg/kg as the recommended upper limit 8
- Dexamphetamine: 0.5 mg/kg as the recommended upper limit 8
- Exceeding these doses requires careful documentation of benefits versus adverse effects 8
Response Rates and Titration
- 70-80% of patients respond to stimulants when properly titrated 2
- Stimulants work within days, allowing rapid assessment of response 2
- Systematic titration to optimal effect is more important than strict mg/kg calculations 2
Common Pitfalls to Avoid
Do not assume low starting doses represent adequate treatment—5 mg of amphetamine salts or methylphenidate is at the very low end of the therapeutic range and will be subtherapeutic for most adults 2. Failure to titrate upward appropriately is a primary cause of apparent "treatment failure" 2.
Do not confuse starting doses with maintenance doses—the initial 5-10 mg doses are titration starting points, not therapeutic endpoints 2, 3. Most adults require 20-40 mg daily of amphetamine salts or equivalent for optimal symptom control 2.
Monitor for tolerance concerns—there is little evidence of tolerance development to stimulant effects on ADHD symptoms, and most patients continue responding to the same dose over prolonged treatment 2. If symptoms worsen, consider environmental factors or comorbidities rather than automatically increasing the dose 2.