What is the first‑line medication and starting dose for a healthy 25‑year‑old adult with newly diagnosed attention‑deficit/hyperactivity disorder?

First-Line Medication and Dosage for Adult ADHD (Age 25)

For a healthy 25-year-old adult with newly diagnosed ADHD, initiate a long-acting stimulant medication—specifically methylphenidate extended-release (e.g., Concerta 18 mg once daily) or lisdexamfetamine (Vyvanse 20–30 mg once daily)—as first-line therapy, titrating weekly by 18 mg or 10–20 mg respectively until optimal symptom control is achieved. 1

Rationale for Long-Acting Stimulants as First-Line

• Stimulants (methylphenidate or amphetamines) are the gold standard first-line pharmacological treatment for adult ADHD, with demonstrated efficacy in 70–80% of patients and the largest effect sizes from over 161 randomized controlled trials. 1, 2
• Long-acting formulations are strongly preferred over immediate-release preparations because they provide better medication adherence, lower risk of rebound effects, more consistent all-day symptom control, and reduced diversion potential—all critical for adults with executive dysfunction. 1
• Amphetamine-based stimulants are preferred for adults based on comparative efficacy studies, though methylphenidate remains an equally appropriate first-line option with robust evidence. 1

Specific Starting Doses and Titration

Methylphenidate Extended-Release (Concerta)

• Start Concerta at 18 mg once daily in the morning. 1
• Titrate by 18 mg weekly based on symptom response and tolerability, up to a maximum of 54–72 mg daily. 3, 1
• Concerta's OROS delivery system provides 8–12 hour coverage with an ascending plasma level pattern, ensuring consistent symptom control throughout the workday and is resistant to tampering. 1

Lisdexamfetamine (Vyvanse)

• Start lisdexamfetamine at 20–30 mg once daily in the morning. 1
• Titrate by 10–20 mg weekly up to a maximum of 70 mg daily. 1
• Lisdexamfetamine is a prodrug formulation that reduces abuse potential while providing once-daily dosing with 10–12 hour symptom coverage. 1

Alternative: Mixed Amphetamine Salts Extended-Release (Adderall XR)

• Start Adderall XR at 10 mg once daily in the morning, titrating by 5 mg weekly up to a maximum of 50 mg daily (therapeutic range 10–50 mg/day). 1, 4
• Some patients may require up to 0.9 mg/kg or 65 mg total daily dose with clear documentation that lower doses were insufficient. 1

Critical Baseline Assessment Before Initiation

• Obtain blood pressure and pulse at baseline, as cardiovascular monitoring is mandatory before starting any stimulant. 1, 4
• Screen for personal and family cardiac history, specifically sudden death in family members, cardiovascular symptoms, Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, and long QT syndrome. 1
• If any cardiac risk factors are present, obtain ECG and consider cardiology referral before starting treatment. 1
• Screen for substance use disorder history, as this requires special consideration (though stimulants can still be used with long-acting formulations). 1, 4

Monitoring During Titration

• Measure blood pressure and pulse at each dose adjustment visit during titration. 1, 4
• Obtain weekly ADHD symptom ratings during dose adjustment, specifically assessing functional improvement across work, home, and social settings. 1
• Monitor for common adverse effects including appetite suppression, insomnia, headache, and anxiety. 1, 4
• Track weight at each visit, as appetite suppression is a common side effect. 1

When to Consider Non-Stimulants (Second-Line)

• Reserve non-stimulant medications (atomoxetine, guanfacine, clonidine) for patients who have failed or cannot tolerate two or more stimulant trials, or who have active substance use disorder. 1, 5
• Atomoxetine is the only FDA-approved non-stimulant for adult ADHD, with a target dose of 60–100 mg daily (maximum 1.4 mg/kg/day or 100 mg/day, whichever is lower), but requires 6–12 weeks to achieve full therapeutic effect compared to stimulants which work within days. 1, 5
• Atomoxetine has medium-range effect sizes of approximately 0.7 compared to stimulants with effect sizes of 1.0. 1, 5

Absolute Contraindications to Stimulants

• Symptomatic cardiovascular disease or uncontrolled hypertension 1, 4
• Concurrent use of MAO inhibitors (require 14-day washout period) 1, 4
• Active psychosis or mania 1, 4
• Known hypersensitivity to stimulants 1

Common Pitfalls to Avoid

• Do not calculate methylphenidate dose based on body weight (mg/kg)—dose-response variability is not correlated with weight; instead, use systematic weekly titration in increments of 10–18 mg up to the effective maximum to achieve symptom control. 1
• Do not assume the patient will develop tolerance requiring dose escalation—there is little evidence of tolerance development to stimulant effects on ADHD symptoms, and most patients continue to respond to the same dose even over prolonged treatment periods. 1
• Do not prescribe immediate-release methylphenidate for "as-needed" use—ADHD requires consistent daily symptom control throughout the day to prevent functional impairment, and sporadic dosing fundamentally misunderstands ADHD pathophysiology. 1
• Do not discontinue effective ADHD treatment solely due to concerns about "taking medication forever"—untreated ADHD is associated with increased risk of accidents, substance abuse, criminality, and functional impairment. 1

Treatment Algorithm

1. Start with a long-acting stimulant (Concerta 18 mg or lisdexamfetamine 20–30 mg once daily). 1
2. Titrate weekly based on symptom response and tolerability. 1
3. If inadequate response to one stimulant class after adequate trial (6–8 weeks at therapeutic dose), switch to the other class—approximately 40% respond to both, 40% respond to only one. 1
4. Only after failure of two or more stimulants should non-stimulants be considered. 1, 5