Switching from Adderall IR to Dexedrine: Dosing Recommendations
When switching from Adderall IR 10 mg twice daily (total 20 mg/day) to Dexedrine (dextroamphetamine), start with 5 mg twice daily (total 10 mg/day) and titrate upward in weekly increments of 2.5-5 mg per dose based on symptom control and tolerability. 1
Rationale for Starting Dose
Adderall IR contains 75% dextroamphetamine salts and 25% levoamphetamine salts. Since Dexedrine is pure dextroamphetamine, you might expect to need approximately 75% of the Adderall dose (15 mg/day). However, guideline-based practice recommends starting at 5 mg twice daily regardless of prior amphetamine exposure to assess individual response and tolerability 1, 2.
Titration Schedule
- Week 1: Start Dexedrine 5 mg twice daily (after breakfast and lunch)
- Week 2: If inadequate symptom control, increase to 7.5 mg twice daily
- Week 3: If needed, increase to 10 mg twice daily
- Week 4: If needed, increase to 12.5 mg twice daily
Increase doses in weekly increments of 2.5-5 mg per dose until optimal symptom control is achieved 1. The maximum recommended total daily dose is 40 mg 1, 2.
Monitoring During Titration
At each dose adjustment, assess:
- ADHD symptom control using standardized rating scales from multiple sources (patient, family, work/school)
- Side effects: insomnia, appetite suppression, headaches, cardiovascular effects (blood pressure, heart rate), mood changes
- Vital signs: Blood pressure and pulse at each visit 1
- Weight: At each visit to objectively monitor appetite effects 1
Contact should be maintained weekly during titration, either by office visit or telephone 1.
Key Differences Between Adderall and Dexedrine
Dexedrine has a longer duration of action and more pronounced effects on appetite and sleep compared to mixed amphetamine salts due to its longer excretion half-life 1. This means:
- You may achieve adequate coverage with twice-daily dosing (some patients need only once-daily dosing) 1
- Appetite suppression and sleep disturbance may be more prominent
- The final total daily dose may be lower than the Adderall dose
Important Caveats
Do not use alternate-day dosing or skip doses to reduce side effects—this creates significant fluctuations in drug levels and receptor occupancy that can worsen symptom control and increase withdrawal-like effects 3.
Cardiovascular monitoring is essential: Amphetamines increase systolic blood pressure by approximately 2 mmHg, diastolic blood pressure by 2 mmHg, and heart rate by 4 beats per minute 4. These effects are sustained with chronic use and increase cardiovascular risk.
If the patient does not respond adequately at 40 mg total daily dose, consider switching to a different stimulant class (methylphenidate) rather than exceeding maximum recommended doses 1. Higher doses increase side effects without proportional benefit in fixed-dose scenarios, though flexible titration to higher doses may be appropriate in select cases 5.
The goal is the lowest effective dose that controls symptoms without intolerable side effects—not necessarily achieving the same total daily amphetamine dose as before 1, 2.