ADHD Medication Dose Too Low or Too High? Signs

A dose that’s too low leaves your ADHD symptoms undertreated. A dose that’s too high brings side effects that outweigh the benefit. Both are common while your GP finds the right level. This guide covers the signs of each, for dexamphetamine, Vyvanse, Ritalin and Concerta, and how your GP adjusts the dose in Australia.

Too low or too high, at a glance

Use this as a quick reference. The sections below go into more detail, including what to watch for on Concerta and Ritalin specifically.

Signs your dose may be too low	Signs your dose may be too high
Core ADHD symptoms persist and meaningfully affect your day	Emotional blunting, feeling “flat” or “robotic”
The medication wears off well before your next dose is due	Overfocus or hyperfocus on the wrong task
You only notice it’s working when you miss a dose	Physical restlessness or jitteriness
Procrastination and task-switching patterns are unchanged	New anxiety or unease that wasn’t there before medication
Emotional reactivity stays high	Resting heart rate noticeably higher than your own baseline
	Jaw clenching or teeth grinding
	Appetite loss significant enough to affect eating

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Signs your ADHD medication dose is too low in adults

A dose that’s too low means you’re tolerating the medication well but not getting full symptom relief. This is the most common scenario early in titration, because your GP deliberately starts at the bottom of the dosage range. See our guide to what to expect in the first three months on ADHD medication for how this plays out week by week.

Core symptoms persist: you still struggle with sustained attention, starting tasks, or following through on plans, to a degree that meaningfully affects your day.
The medication wears off too quickly: dexamphetamine’s own dosing pattern spaces doses 4 to 6 hours apart, with blood levels peaking around 2 hours after a dose; immediate-release Ritalin follows a similar few-times-a-day pattern. If the effect fades well before your next scheduled dose, or well before Vyvanse’s or Concerta’s lasting windows, the dose may be insufficient.
You only notice the medication when it is not there: a subtle improvement that becomes obvious when you miss a dose suggests it’s working, but not at full therapeutic effect.
Procrastination and task-switching remain unchanged: if the patterns that prompted your diagnosis haven’t shifted at all, a higher dose is worth trialling.
Emotional reactivity stays high: ADHD-related emotional dysregulation often improves with adequate stimulant dosing.

A dose that’s too low is safe. It simply means there’s room to increase within the therapeutic range. Your GP may raise the dose in small increments at your next review.

Signs your dose is too high

A dose that’s too high produces side effects that outweigh the benefits. The line between effective and too much is individual, but certain patterns are consistent warning signs.

Emotional blunting: feeling flat, detached, or like your personality has dulled. Some people describe feeling “robotic” or losing their sense of humour. This is one of the clearest signals a dose is too high.
Overfocus or hyperfocus on the wrong things: spending three hours organising a spreadsheet nobody asked for, while the task you needed to do remains untouched.
Physical restlessness or jitteriness: an internal buzzing or inability to sit still, distinct from ADHD restlessness. More like too much caffeine.
Anxiety or a sense of unease: new-onset anxiety that wasn’t present before medication or at lower doses. This is dose-dependent and typically resolves when the dose is reduced.
Elevated resting heart rate: stimulant medicines raise heart rate by an average of about 3 to 6 beats per minute and blood pressure by about 2 to 4 mmHg, though individual increases can be larger. A resting heart rate noticeably higher than your own baseline, especially if it feels sustained rather than a one-off, is worth flagging at your next review.
Jaw clenching or teeth grinding: particularly with dexamphetamine and Vyvanse at higher doses.
Significant appetite loss or weight loss: some appetite suppression is expected, but rapid weight loss or inability to eat throughout the day suggests the dose is too high.

These signs apply whether you’re on dexamphetamine, Vyvanse, Ritalin or Concerta. Contact your GP to discuss stepping back to the previous dose.

Signs it might be the wrong medication

Sometimes the issue isn’t the dose but the medication itself. Amphetamine-based stimulants (Vyvanse, dexamphetamine) and methylphenidate-based stimulants (Ritalin, Concerta) work through different mechanisms, as explained in our guide to how GPs choose between dexamphetamine, Vyvanse and Ritalin. Responding poorly to one class doesn’t predict your response to the other.

You’ve trialled a full dose range without adequate benefit: if you’ve been titrated to the upper end of the recommended range and still see no meaningful symptom improvement, switching class is worth discussing.
Side effects are persistent across multiple doses: if a particular side effect, such as anxiety, insomnia or nausea, occurs at every dose level, a different stimulant or a non-stimulant medication might suit you better.
The medication works but the rebound is unbearable: severe mood crashes as the medication wears off, despite trying different timing strategies, may indicate the formulation isn’t right for your metabolism.
You experience intolerable side effects at therapeutic doses: the dose that controls your symptoms also causes side effects you can’t live with. A different medication may give the same benefit without the same profile.

Most adults with ADHD respond well to at least one stimulant medication. If stimulants as a class don’t work for you, or the side effects are unmanageable on both classes, non-stimulant options such as atomoxetine (Strattera) and guanfacine are available in Australia.

How your GP adjusts the dose

Dose adjustment follows a structured process, not a fixed schedule. Your GP raises or lowers the dose based on your reported symptom improvement and side effects. The Australian ADHD guideline says your GP should review your progress regularly during titration, with heart rate and blood pressure checked before and after every dose change. The Vyvanse and Concerta product information both require patients to be reviewed at least annually to confirm treatment is still needed, so ongoing reviews on any of these medicines happen at least that often.

Start low: begin at the bottom of the dose range.
Increase gradually: raise the dose in small increments. The Australian ADHD guideline says your GP should review your progress regularly during titration, without a fixed interval; how often depends on your response.
Assess at each step: your GP asks about symptom control, side effects, sleep, appetite and mood.
Find the sweet spot: the target is the lowest dose that gives you good symptom control with tolerable side effects.
Stabilise: once optimised, follow-up moves to an individualised schedule based on your response and circumstances, with heart rate and blood pressure checked at least every 6 months. See our guide to what your GP checks during ongoing monitoring for the full schedule.

If your GP uses structured follow-up questionnaires between appointments, it’s easier to track how the medication is affecting you day to day, and you get more value from the time you spend in each review.

TGA-approved dosage ranges for Australian ADHD medications

The TGA-approved product information for these medicines is written mostly for children, because that is where each medicine’s ADHD indication sits. Adult dosing follows from that starting point, off-label but standard, PBS-subsidised practice, adjusted to your individual response. Where the product information does give an adult figure directly, such as for Vyvanse, Concerta and Ritalin LA, it is shown below.

Vyvanse (lisdexamfetamine): the product information states a starting dose of 30 mg once daily in the morning, whether you’re new to treatment or switching from another medicine, with a maximum of 70 mg a day (doses above that haven’t been studied). Available in 20, 30, 40, 50, 60 and 70 mg capsules. Taken in the morning, because afternoon doses can cause insomnia. Not studied in adults over 55.
Dexamphetamine: the product information’s ADHD dosing table is written for children, not adults. For ages 6 to 12 it starts at 5 mg daily, raised in 5 mg increments at weekly intervals; for ages 12 and over it starts at 10 mg daily, raised in 10 mg increments weekly. Younger children have a stated ceiling of 40 mg daily in two divided doses, the first on waking and any additional dose 4 to 6 hours later. There is no adult ADHD dosing table in the product information; adult use is off-label but standard, PBS-subsidised practice. The “40 mg” figure some Queensland patients hear about is a separate, state-based threshold, not this TGA figure: prescribing above 40 mg a day under Queensland’s specialist-GP pathway needs an additional section 75 approval. Caps differ by state; see our state-by-state guide to where GPs can prescribe ADHD medication.
Methylphenidate IR (Ritalin): the product information’s immediate-release dosing table (starting at 5 mg once or twice daily, raised in 5 to 10 mg increments weekly, up to a ceiling of 60 mg daily) is written for children and adolescents. For adults, the product information says only the long-acting Ritalin LA capsule should be used for ADHD, not the short-acting tablet, though the tablet is still prescribed in some adult cases in practice.
Methylphenidate ER (Concerta): adults start at 18 or 36 mg daily, adjusted in 18 mg increments, usually at roughly weekly intervals, to a maximum of 72 mg daily. Children and adolescents (6 and over) are adjusted the same way but capped at 54 mg daily. Taken once daily in the morning, designed for a 12-hour duration of effect.
Methylphenidate ER (Ritalin LA): adults not already taking methylphenidate usually start at 20 mg once daily (a lower 10 mg start is possible on clinical judgement), adjusted in 20 mg increments to a maximum of 80 mg daily. Children and adolescents are capped at 60 mg daily. The product information doesn’t state a duration of effect for Ritalin LA, unlike Concerta’s stated 12 hours.

Stimulant medication is prescribed for ADHD, not weight loss. Lisdexamfetamine (Vyvanse) is TGA-approved for moderate to severe binge eating disorder in adults under psychiatrist management, but none of these medicines are approved or routinely prescribed for weight loss on their own.

Your GP won’t jump straight to the maximum dose. The titration process above is designed to get you to the right dose for your body without overshooting.

When to talk to your GP

Book a review with your GP if any of the following apply:

Your medication was working well but has become less effective over weeks or months
Side effects that initially settled have returned or worsened
You’ve started a new medication, for any condition, that might interact with your stimulant
Your weight has changed significantly (stimulant doses aren’t weight-based, but body composition changes can affect response)
Hormonal changes (menstrual cycle, pregnancy, perimenopause) are affecting how the medication works
You’re experiencing emotional blunting, persistent anxiety, or mood changes
You’re considering stopping your medication

If you haven’t been assessed yet, start by finding a GP who assesses ADHD in your state.

This page is general information about ADHD medication in Australia, not advice about your individual treatment. Do not start, stop or change a dose without talking to the clinician who prescribed it. If you experience chest pain, fainting, or thoughts of self-harm, contact your prescriber or call emergency services on 000.

Frequently asked questions

How often should my GP review my ADHD medication dose?

The Australian ADHD guideline says your GP should review your progress regularly during titration, without a fixed interval; some GPs check in weekly by phone or telehealth, others less often, depending on how you’re responding. Heart rate and blood pressure are checked before and after every dose change, and at least every 6 months once you’re stable.

Is it normal for ADHD medication to stop working after a few months?

Perceived reduced effectiveness is common and has several explanations. Tolerance to the initial noticeable effects can develop, though the therapeutic benefit often remains. Changes in sleep, stress, diet or hormones can all affect how well the medication works. A GP review can determine whether a dose adjustment is needed or whether other factors are at play.

How do I know if my Concerta or Ritalin dose needs adjusting?

The same signs apply as with any ADHD medication. If Concerta or Ritalin wears off well before its next dose is due, or before the day is over, your dose may be too low. Feeling flat, jittery or unusually anxious can mean it’s too high. Because Concerta and Ritalin LA release gradually over the day, a dose that’s too high on these tends to build steadily rather than spike sharply the way a short-acting tablet can. Track when you notice changes and bring that detail to your GP.

Can I ask my GP to increase my ADHD medication dose?

If your current dose is within the approved range and you feel it isn’t providing adequate symptom control, discuss this with your GP. Bring specific examples of how symptoms are affecting your daily life. Your GP will weigh the potential benefit of a higher dose against the risk of increased side effects.

What’s the difference between the medication wearing off and tolerance?

Wearing off is the normal end of a dose period. Dexamphetamine doses are spaced 4 to 6 hours apart per the product information, and Ritalin IR follows a similar few-times-a-day pattern; you’ll feel each dose fade as the next one becomes due. Tolerance means the same dose gives less benefit over time, beyond that normal pattern. If you feel your medication is less effective, your GP can help work out whether it’s a dosing, timing or tolerance issue.

Should I take a break from ADHD medication to prevent tolerance?

Medication breaks are sometimes used in children to assess ongoing need, but they aren’t routinely recommended for adults. Stopping suddenly can cause rebound symptoms. If you’re considering a break, discuss the timing and approach with your GP first. Some adults take weekends off short-acting stimulants, but this is an individual decision made with your prescriber.

Where GPs can prescribe ADHD medication, state by state
Find a GP who assesses ADHD in your state

Sources

TGA Product Information: Aspen Dexamfetamine, dexamfetamine sulfate (Aspen Pharmacare Australia), TGA eBS document CP-2023-PI-02524-1, read directly on TGA eBS 4 September 2026
TGA Product Information: Vyvanse, lisdexamfetamine dimesilate (Takeda Pharmaceuticals Australia), TGA eBS document CP-2013-PI-02051-1, PI V12.0 (CCDS V40), read directly on TGA eBS 4 September 2026
TGA Product Information: Ritalin and Ritalin LA, methylphenidate hydrochloride (Novartis Pharmaceuticals Australia), TGA eBS document CP-2010-PI-03175-3, read directly on TGA eBS 4 September 2026
TGA Product Information: Concerta, methylphenidate hydrochloride (Janssen-Cilag), TGA eBS document CP-2009-PI-00919-3, API v3.0, read directly on TGA eBS 4 September 2026
AADPA Australian Evidence-Based Clinical Practice Guideline for ADHD, First Edition, October 2022, Summary of Recommendations (adhdguideline.aadpa.com.au, recommendations 5.1.5 and 5.7.7, read 4 September 2026)

General health information

This article is general health information only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always speak with a qualified health professional before making any changes to your medication or treatment plan.

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