How Long Does ADHD Medication Take to Work — and How Long Does It Last?

Short answer: Stimulant ADHD medicines act quickly — short-acting forms start working soon after you take them¹ — so many people notice an effect on the first day. Getting the dose right takes longer: doses are usually increased gradually over three or four weeks.² Non-stimulant medicines are slower to take effect than stimulants.³

How quickly stimulants start working

Short-acting medicine works soon after you take it, but only for a limited time; long-acting medicine is slower to start working, but its effects last longer.¹ Which suits you depends on how your day is structured and how you respond to the medicine.

How long a dose lasts

Better Health Channel describes short-acting (immediate-release) stimulants as lasting about 3 hours, and long-acting forms as lasting about 6–8, 10–12 or more than 12 hours, depending on the medicine.² A long-acting medicine can cover a full working or school day, while a short-acting one may be used to cover a particular part of the day.

Why finding the right dose takes weeks

Doses are adjusted step by step, based on how well your symptoms are controlled, how you’re functioning, and any side effects.⁴ The Australian ADHD Guideline describes small increases at weekly, fortnightly or monthly intervals,³ and Better Health Channel notes the dose may be increased gradually over 3 or 4 weeks.² With us, that’s the monthly medication reviews in the first months of treatment — see how our assessment works.

Non-stimulant medicines take longer

Non-stimulant medicines are used when stimulants aren’t suitable, aren’t tolerated or haven’t worked.⁴ They have a slower onset of effect than stimulants,³ so it takes longer to judge whether one is working.

What your doctor checks along the way

At reviews, your doctor checks how well the medicine is working and any side effects — such as appetite, sleep, mood and anxiety — and your heart rate and blood pressure, before and after each dose change and every six months.⁴

If it doesn’t seem to work

Tell your doctor rather than changing the dose yourself. The answer may be a dose or timing change, a different form of the medicine, or a different medicine altogether.

Frequently asked questions

How long does ADHD medication take to work?

Stimulant medicines act on the day you take them — short-acting forms soon after a dose. Finding the right dose usually takes a few weeks of gradual adjustment. Non-stimulant medicines take longer to show their effect.

How long does ADHD medication last?

Short-acting stimulant medicines last about 3 hours. Long-acting forms last about 6–8, 10–12 or more than 12 hours, depending on the medicine.

How long does ADHD medication stay in your system?

The effects of a dose last for the hours the medicine is designed to cover. How long a medicine can be detected in a test is a separate question that depends on the medicine and the test — ask your doctor or pharmacist.

What if my ADHD medication doesn’t seem to work?

Tell your doctor rather than changing the dose yourself. It may be the dose, the timing or the form of the medicine, and there are other options, including non-stimulant medicines.

Next steps

Read ADHD medication in Australia, does ADHD medication cause weight loss? and is ADHD medication addictive?

This article is general information only and is not medical advice. Don’t start, stop or change a medicine without talking to your doctor. ADHD GP is a private telehealth clinic staffed by AHPRA-registered Australian GPs.

Book your ADHD assessment

References

1. healthdirect (Australian Government). ADHD medicines — children and adults. 2025. www.healthdirect.gov.au — Stimulants adjust dopamine and noradrenaline; short-acting forms work soon after a dose and long-acting forms last longer; common side effects include reduced appetite, weight loss, anxiety, irritability and insomnia, and stimulants can raise blood pressure; prescribing is tightly controlled and there is a risk of dependence if not taken as prescribed.
2. Better Health Channel (Victorian Government). ADHD — therapies. 2026. www.betterhealth.vic.gov.au — Stimulants act on dopamine release; short-acting forms last about 3 hours and long-acting forms 6–12+ hours; doses may be increased gradually over 3–4 weeks; there is no evidence ADHD is caused by food additives.
3. Australian ADHD Professionals Association. Australian ADHD Guideline — Chapter 5: pharmacological interventions. 2022. adhdguideline.aadpa.com.au — Stimulants have a more rapid onset of therapeutic effect than non-stimulant medicines; doses are adjusted in small increments at weekly, fortnightly or monthly intervals.
4. Australian ADHD Professionals Association. Australian ADHD Guideline — summary of recommendations. 2022. adhdguideline.aadpa.com.au — Recommends stimulants as first-line medication for adults with impairing ADHD and non-stimulants where stimulants are unsuitable; dose titration with monitoring of heart rate, blood pressure, weight, sleep, mood and anxiety; cognitive-behavioural interventions, coaching and lifestyle guidance; notes anxiety, depression and substance use may follow untreated ADHD.

Sources were last checked on 5 October 2026. See all sources used on this site on our Sources page.