Can a 10 mg capsule of dexmethylphenidate (short-acting stimulant) be added as needed to an established ADHD patient on 40 mg of Vyvanse (lisdexamfetamine) who requires an increase in stimulant dose?

From the FDA Drug Label

DOSAGE AND ADMINISTRATION • Patients new to methylphenidate: Recommended starting dose is 5 mg once daily for pediatric patients and 10 mg once daily for adults with or without food in the morning ( 2.2). • Patients currently on methylphenidate: Dexmethylphenidate hydrochloride extended-release capsules dosage is half (1/2) the current total daily dosage of methylphenidate ( 2. 2). • Patients currently on dexmethylphenidate hydrochloride immediate-release tablets: Give the same daily dose of dexmethylphenidate hydrochloride extended-release capsules ( 2. 2). • Titrate weekly in increments of 5 mg in pediatric patients and 10 mg in adult patients ( 2.2). • Maximum recommended daily dose: 30 mg in pediatric patients and 40 mg in adults ( 2. 2). • Capsules may be swallowed whole or opened and the entire contents sprinkled on applesauce ( 2.3).

The FDA drug label does not provide information on adding a 10 mg capsule of dexmethylphenidate as needed to an established ADHD patient on 40 mg of Vyvanse who requires an increase in stimulant dose. The label provides dosage information for patients new to methylphenidate, currently on methylphenidate, or currently on dexmethylphenidate hydrochloride immediate-release tablets, but it does not address the specific scenario of adding a short-acting stimulant to a patient already on a long-acting stimulant like Vyvanse 1.

From the Research

Adding a 10 mg capsule of dexmethylphenidate as needed to an established ADHD patient already taking 40 mg of Vyvanse is generally not recommended. This combination would involve two different stimulant medications with overlapping mechanisms of action, which increases the risk of additive side effects including elevated heart rate, blood pressure, anxiety, and insomnia 2. Instead, the preferred approach would be to either increase the Vyvanse dose (up to a maximum of 70 mg daily) or switch completely to dexmethylphenidate if Vyvanse is not providing adequate symptom control. Some key points to consider:

• The patient's current symptoms should be evaluated to ensure they are truly related to ADHD and not to other conditions that might mimic attention problems.
• If the patient specifically needs additional coverage later in the day as Vyvanse wears off, this should be discussed with their prescriber who might consider a scheduled (not as-needed) afternoon dose of a short-acting stimulant.
• Any stimulant adjustment should be made under close medical supervision with regular monitoring of vital signs and side effects.
• A study from 2022 found that flexible titration of stimulant doses, considering the presence of ADHD symptoms and tolerated side effects, is associated with improved efficacy and acceptability 3.
• Another study from 2020 found that dose adjustment over time in some patients meant using higher doses than those generally recommended, but these children experienced more growth attenuation without other significant treatment complications 4. However, the most recent and highest quality study from 2025 recommends methylphenidate and lisdexamfetamine as first-line pharmacological treatment options for adults with ADHD, and suggests that formulations of methylphenidate can be classified into three groups according to their duration of action 2. Therefore, the best course of action would be to increase the Vyvanse dose or switch to dexmethylphenidate under close medical supervision.