Key facts
Generic name
Dexamfetamine sulfate
UK brand
Amfexa, and generic dexamfetamine
Class
Stimulant, immediate release
Onset
Usually within about 30 to 60 minutes
Typical duration
4 to 6 hours
UK licence
Children and adolescents aged 6 to 17. Adult use is off-label
Legal status
Schedule 2 controlled drug
What dexamfetamine is
Dexamfetamine is an amfetamine-based stimulant licensed for ADHD in the UK, sold as Amfexa and as a generic. It increases the availability of dopamine and noradrenaline in the parts of the brain that handle attention, motivation and impulse control.
Its relationship with lisdexamfetamine is worth understanding. Elvanse is a prodrug: the capsule is inactive, and the body converts it into dexamfetamine over several hours. Amfexa is that same dexamfetamine, given directly. The molecule doing the work is identical; what differs is how quickly it arrives and how long it stays.
That makes dexamfetamine fast-acting and relatively short-lived, at four to six hours. It is one of the three stimulant options licensed here, alongside methylphenidate and lisdexamfetamine.
Who it is prescribed for in the UK
The UK licence is narrower than people assume. Amfexa and generic dexamfetamine are licensed as part of a comprehensive treatment programme for ADHD in children and adolescents aged six to seventeen, where the response to previous methylphenidate treatment has been clinically inadequate. The product information states plainly that the tablets are not licensed for use in adults.
That does not mean adults are never prescribed it. It means adult prescribing is off-label: a specialist can do it where it is clinically justified, taking on the responsibility that goes with prescribing outside a licence and explaining the position to you. In practice it is prescribed less often than methylphenidate or lisdexamfetamine, and is usually considered where those have not suited.
NICE guideline NG87 offers methylphenidate first to children and young people, and either methylphenidate or lisdexamfetamine first to adults. Dexamfetamine is considered where those have not helped enough or have not been tolerated.
Clinical context
Where a short-acting stimulant is useful
A four to six hour duration is sometimes exactly what is wanted. It suits people who need cover for a defined part of the day, such as a morning of study or a specific shift, and people who are very sensitive to a stimulant still being active in the evening.
It is also sometimes used alongside a longer-acting medicine to extend cover at the end of the day, which is a specialist decision rather than something to arrange independently.
Baseline height, weight, pulse and blood pressure are checked before starting and monitored during treatment. It is generally avoided where there is significant cardiovascular disease, uncontrolled high blood pressure, hyperthyroidism or glaucoma, and it is not combined with monoamine oxidase inhibitors.
Dosage and titration in the UK
Amfexa is available as 5mg, 10mg and 20mg tablets. Treatment usually starts at a low dose and is increased in weekly steps. Because each dose lasts four to six hours, it is normally taken two or three times a day rather than once.
Spacing matters. Doses are usually taken in the morning and early afternoon, with the last one early enough not to interfere with sleep. Working out that spacing is a large part of what titration is for.
Our guide to titration explains what the appointments involve and how progress is tracked. The aim is the lowest dose that gives a useful benefit with side effects you find acceptable.
Controlled drug
Dexamfetamine is Schedule 2, so it is treated differently from ordinary medicines rather than issued as a repeat prescription, each prescription covers about a month, and identification may be requested at the pharmacy. Once your dose is stable, prescribing can sometimes move to your GP under a shared care agreement, although a practice can decline.
How long dexamfetamine lasts
A dose typically lasts four to six hours, with the effect usually noticeable within 30 to 60 minutes. That is considerably shorter than the modified-release options and much shorter than lisdexamfetamine, which can cover up to 13 or 14 hours.
The shorter duration cuts both ways. It gives more control: you can place cover where you need it and leave the evening clear. It also asks more of you, because a second or third dose has to be remembered during the day, which is not a trivial ask for someone with ADHD.
Some people notice the effect wearing off more distinctly than they would with a modified-release product, sometimes with tiredness or low mood as it fades. If that happens consistently it is worth raising, because it is often addressed by adjusting the dose or the spacing.
How dexamfetamine compares
The shortest-acting of the amfetamine-based options licensed here.
Scroll the table sideways to see every column.
Choosing between them is mostly a question of how the day is shaped rather than of one being stronger. A long-acting option removes the need to remember a second dose, which matters a great deal to some people. A short-acting one gives finer control over when cover starts and stops.
Response also differs between the two families. Some people do noticeably better on an amfetamine-based medicine than on methylphenidate, or the reverse, and there is no way to predict which in advance. Trying one and adjusting is a normal part of treatment rather than a sign that something has gone wrong.
Dexamfetamine side effects
Like all medicines, dexamfetamine can cause side effects, and not everyone gets them. Most are mild, appear early, and settle within the first few weeks. Our general guide to ADHD medication side effects covers all the licensed options.
Common
- Reduced appetite, and sometimes weight loss
- Difficulty getting to sleep
- Dry mouth
- Headache
- Feeling anxious, restless or irritable
- A modest rise in heart rate or blood pressure
Less common
- Low mood, or mood becoming more changeable
- Tics, or existing tics becoming more noticeable
- Slowed growth in children, which is why height and weight are monitored
- Palpitations
When to contact your prescriber
Seek medical advice promptly for chest pain, breathlessness, fainting, a fast or irregular heartbeat, signs of poor circulation in the fingers or toes, or new or worsening thoughts of self-harm. Seek advice urgently if reality starts to feel distorted, for example hearing or seeing things that are not there, believing things other people do not, or becoming unusually suspicious; or if mood becomes unusually elevated, racing or overactive with little need for sleep. Do not stop the medication abruptly without advice. Suspected side effects can also be reported through the MHRA Yellow Card scheme.
- Appetite and weight Why it happens and how it is managed
- Alcohol Risks and practical guidance
- Driving and the DVLA What you must declare
Common questions
Is Amfexa the same as dexamfetamine?
Yes. Amfexa is a UK brand of dexamfetamine. Generic dexamfetamine contains the same active ingredient.
How is dexamfetamine different from Elvanse?
Elvanse is a prodrug that the body converts into dexamfetamine over several hours, which gives a gentle build and a long tail of up to 13 or 14 hours. Dexamfetamine is given directly, so it acts faster and lasts four to six hours.
Is dexamfetamine the same as Adderall?
No. Adderall is a mixture of amfetamine salts and has never been licensed in the UK. Dexamfetamine is a single ingredient and is licensed here. Our guide to Adderall in the UK explains the alternatives.
How many times a day is it taken?
Usually two or three times, because each dose lasts four to six hours. The exact spacing is worked out during titration.
Is dexamfetamine licensed for adults in the UK?
No. The licence covers children and adolescents aged six to seventeen, and the product information states the tablets are not licensed for use in adults. Adults are sometimes prescribed it off-label by a specialist where it is clinically justified.
Can I drink alcohol on dexamfetamine?
The product information advises abstaining from alcohol during treatment, because alcohol may worsen the effects of the medicine on the central nervous system. Our alcohol guide covers what that means in practice.
Is dexamfetamine a controlled drug?
Yes. It is Schedule 2 in the UK, so it is treated differently from ordinary medicines rather than issued as a repeat prescription, each prescription covers about a month, and identification may be requested at the pharmacy.
Important
This information is general and educational. It is not a substitute for medical advice. Decisions about starting, changing or stopping ADHD medication are always made together with a Consultant Psychiatrist following a full assessment.
Considering an ADHD assessment?
Any conversation about medication starts with a diagnosis. Our GMC-registered Consultant Psychiatrists assess adults and children. Assessments are £695 online and £1,095 in person in London or Manchester.
No GP referral needed. Appointments are usually available within weeks.
References
- Attention deficit hyperactivity disorder: diagnosis and management (NG87) National Institute for Health and Care Excellence
- Dexamfetamine sulfate British National Formulary
- Dexamfetamine NHS medicines A to Z
- Controlled drugs: list of drugs and their classification GOV.UK
Last reviewed September 2026. Next review due September 2027.
