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Medication guide

Dexamfetamine (Amfexa)

Dexamfetamine sulfate

Dexamfetamine is a short-acting stimulant for ADHD, also sold as Amfexa. Each dose usually helps for around 3–6 hours. This guide explains timing, adult off-label use, side effects and when to get help.

StimulantShort-actingTwice or three times dailySchedule 2 CD

Written and clinically reviewed by ADHD Advanced Practitioner and Clinical Prescribing Pharmacist

Reading time: about 8 minutesLast reviewed: Next review: Download the one-page summary (PDF)

Dexamfetamine: key facts

What it is
A short-acting stimulant tablet for adult ADHD. It's the same active ingredient as Elvanse: dexamfetamine: taken directly, rather than released gradually from a prodrug. Each dose lasts around 3–6 hours.
How to take it
Usually twice or three times daily: morning, midday, and sometimes early afternoon. With or without food; but preferably with or just after meals. Timing matters: the last dose should be early enough not to affect sleep.
When it kicks in
Within about 30–60 minutes of each dose.
Most common early effects
Reduced appetite (especially through the day), difficulty falling asleep, dry mouth and mild headaches. Most settle within 1–2 weeks.
When to get urgent help
Call 999 for severe or spreading chest pain, severe breathlessness, sudden weakness or difficulty speaking, a first seizure, a suspected overdose or a severe allergic reaction. Get urgent help for mild chest pain or a racing heartbeat at rest, hallucinations or thoughts of self-harm (call 999 if you might act on them). Full guide in Section 6.
Section 1

What is dexamfetamine?

Dexamfetamine is the same active ingredient as Elvanse, taken directly rather than released slowly from a prodrug. In adults it is an off-label use in the UK, supported by NICE guideline NG87.

Dexamfetamine at a glance

Dexamfetamine: key facts at a glance, each with its source
FactDetail
Active ingredientDexamfetamine sulfate: the same active ingredient as Elvanse, taken directlySource: Amfexa SmPC (eMC)
Medicine typeShort-acting stimulant tablet (an oral solution is also available). Schedule 2 controlled drugSource: BNF: dexamfetamine sulfate
Strengths5 mg generic tablets; Amfexa 5 mg, 10 mg and 20 mg tablets; oral solution 5 mg/5 mLSource: BNF: dexamfetamine sulfate
Usual starting dose (adults)5 mg twice a day, increased by 5 mg no faster than weeklySource: BNF: dexamfetamine sulfate
Maximum dose60 mg a day, in 2–4 divided dosesSource: BNF: dexamfetamine sulfate
How long it lastsAbout 3–6 hours per dose
When to take itOn waking, around midday, and sometimes early afternoon. Last dose at least 4–6 hours before bed
FoodWith or without food; but preferably with or just after meals
Use in adultsOff-label for adult ADHD in the UK, supported by NICE guideline NG87Source: NICE guideline NG87

When it's prescribed

In adults, this is an off-label (unlicensed) use in the UK, supported by NICE guideline NG87. Most commonly used when someone responds well to Elvanse but finds the longer duration doesn't suit them, or when shorter coverage is clinically preferable.

Pros of dexamfetamine

  • Precise, flexible dosing: effect length can be managed dose by dose
  • Same active ingredient as Elvanse: familiar if you've already used Elvanse
  • Liquid option available for those who can't swallow tablets
  • Can be stopped between doses (some people skip afternoon dose at weekends)
  • Predictable window: you know roughly when each dose will wear off

Cons of dexamfetamine

  • Multiple doses required each day: easy to forget the midday dose
  • Wearing-off effect (rebound) can cause a mood dip between doses or in the evening
  • Schedule 2 Controlled Drug: keep it secure; never share it
  • Cannot be taken within 14 days of stopping an MAOI antidepressant
  • Off-label for adult ADHD: your prescriber should explain this
Section 2

How does dexamfetamine work?

Dexamfetamine is active as soon as it reaches your bloodstream. That gives a faster start, within 30–60 minutes, and a shorter finish of about 3–6 hours per dose.

Dexamfetamine is the active ingredient in Elvanse: the same molecule.

The difference is delivery. Elvanse is a prodrug: when you swallow it, nothing happens until your red blood cells slowly convert it to dexamfetamine over a few hours. That conversion creates a long, smooth, gradually rising effect that lasts all day from a single capsule.

Dexamfetamine tablets don't need converting. They're active as soon as they reach your bloodstream. That means a faster start: you'll often feel something within 30–60 minutes: but also a shorter finish: each dose typically lasts 3–6 hours, then wears off.

This is not a flaw. For some people, the long coverage of Elvanse is too much; it affects sleep, or the all-day effect feels too restrictive. Dexamfetamine lets you match the medication more precisely to your day: take it when you need it, let it wear off when you don't.

Once absorbed, dexamfetamine boosts two brain chemicals in the areas most affected by ADHD. Dopamine is your brain's "is this worth doing?" signal: low dopamine is why starting tasks feels genuinely hard. Noradrenaline is your brain's signal-to-noise filter; it helps the planning part of your brain focus on what matters and filter out distractions. Unlike some medications that only block reabsorption of these chemicals, dexamfetamine actively pushes more of them into the synapse: which is why the effect is noticeable and why the dose is carefully titrated.

This is helpful for ADHD symptoms such as impulsivity, emotional reactivity, poor task initiation and reward-driven behaviours, such as binge eating, impulse spending or constantly seeking stimulation.

However, because dexamfetamine can have a stronger releasing effect on dopamine and noradrenaline, some people may experience more side effects, such as poor sleep, vivid dreams, feeling overstimulated, or circulation-related symptoms such as cold fingers, colour changes or Raynaud’s-type symptoms. If this happens, and it is clinically appropriate, a trial of methylphenidate may be considered, as it can still improve ADHD symptoms but may be better tolerated for some people.

How dexamfetamine works: visual guide

Follow a dexamfetamine tablet from swallowing to effect. Use ADHDnotepad's animated visual medication journey to see how dexamfetamine is already active when taken, is absorbed quickly into the bloodstream and directly increases dopamine and noradrenaline in the synapse, which is why it starts and fades sooner than Elvanse.

ClinicalDeeper clinical detail

Dexamfetamine sulfate is a direct-acting sympathomimetic amine and the active metabolite of lisdexamfetamine (Elvanse). Unlike lisdexamfetamine, it requires no prodrug conversion; it is pharmacologically active immediately upon absorption.

d-Amphetamine acts primarily as a releasing agent and reuptake inhibitor of dopamine and noradrenaline at presynaptic neurons, and to a lesser extent serotonin. It also exerts weak monoamine oxidase inhibitory activity. The net effect is substantially increased monoaminergic neurotransmission in prefrontal cortical circuits governing executive function, attention, and impulse regulation.

The immediate-release formulation produces a faster Tmax (~1–2 hours) and shorter duration of effect (3–6 hours) compared to lisdexamfetamine (12–14 hours). Multiple daily doses are required to provide daytime coverage. The short half-life contributes to the rebound phenomenon: a transient decrease in dopaminergic tone as each dose clears.

Adult use is off-label in the UK. NICE NG87 explicitly supports prescribing dexamfetamine for adult ADHD where clinically indicated. Prescribers should document the off-label rationale.

Section 3

How do I take dexamfetamine?

Most people take dexamfetamine two or three times a day: on waking, around midday, and sometimes early afternoon. Your last dose must be early enough not to affect your sleep.

Interactive dexamfetamine duration & effect chart

See how dexamfetamine may cover your day across more than one dose. Use ADHDnotepad's interactive dexamfetamine effect chart to choose how many doses you take, drag the time of each one and switch metaboliser speed, and explore when each dose may start working, peak and wear off. The chart is illustrative, as actual onset and duration vary between people.

When to take it

Usually twice or three times a day. A common pattern: first dose on waking (or at breakfast), second dose around midday or 4–5 hours later, third dose (if prescribed) in the early-to-mid afternoon: no later than 2–3pm for most people. The cut-off for your last dose matters: because each dose wears off in 3–6 hours, a late dose can still interfere with sleep.

Food: preferably with or just after meals

Take it with or without food; but preferably with or just after meals. That way you have eaten a proper meal before your appetite drops. Food does not reduce how much medication is absorbed, but it can slightly delay the peak effect, so it may feel less abrupt for some people. Bonus tip: a higher-protein breakfast can be helpful for ADHD. Protein provides amino acids, which your body uses to help make neurotransmitters such as dopamine and noradrenaline. This does not replace medication, but it can support steadier energy, concentration and appetite control through the day.

Swallowing the tablets

Swallow whole with a glass of water. If using the oral liquid (5 mg/5 mL): measure the prescribed amount with the oral syringe provided. Take directly or mix with a small amount of water. Once opened, use the bottle within 30 days: write the opening date on it.

Missed dose

Missed your morning dose: take it as soon as you remember, but only if there's still enough time before your next dose is due. Missed your midday dose: check the time: if taking it now would push your last dose too late, skip it and continue tomorrow. Never double up.

Titration period

Almost always started at 5mg once or twice a day, increased gradually at weekly intervals. This isn't a sign it 'isn't working': it's your prescriber finding the lowest dose that gives you the best benefit with the fewest side effects.

Don't combine with

MAOIs (a type of antidepressant): absolute no: cannot be taken within 14 days of stopping one. SSRIs and SNRIs: usually fine, but do carry the risk of Seretonin Syndrome, so speak to your prescriber. Large amounts of vitamin C (orange juice is fine) around the time of your dose: can reduce absorption. Antacids or sodium bicarbonate (e.g Gaviscon, Remmies etc.): can increase absorption. Always tell your prescriber and pharmacist about everything you take.

Drug testing

Dexamfetamine will produce a positive result for amphetamines on any standard drug test: urine, saliva, or blood. This applies to workplace, legal, sporting, and roadside testing. Carry your prescription or a letter from your prescriber. The law provides a statutory medical defence for roadside tests if you are taking a prescribed dose and are not impaired.

ClinicalPrescribing and clinical detail

UK dosing (BNF/SCP): start at 5 mg twice daily, increasing by 5 mg at intervals of at least one week, guided by response and tolerability. Maximum: 60 mg/day in 2–4 divided doses. Last dose should be at least 4–6 hours before bedtime to avoid sleep disruption.

Blood pressure and heart rate: measure at baseline and after each dose increase, then at minimum every 6 months once stable. Obtain personal and family history of cardiac conditions before initiation.

Schedule 2 Controlled Drug: prescriptions must comply with CD requirements (quantity in words and figures, no repeats). Maximum 30 days' supply per prescription.

Adult use is off-label under NICE NG87: document rationale in clinical records.

Renal impairment: no manufacturer dose guidance: apply 'start low, go slow' with closer monitoring. Hepatic impairment: consider hepatic function before initiating; monitor more closely.

Tics: assess pre-treatment. Caution required but not an absolute contraindication. If tics develop or worsen, review: may require dose adjustment or medication change.

Section 4

What should I expect from dexamfetamine week by week?

You will usually start on 5 mg once or twice a day, increased gradually at weekly intervals. The effect is noticeable from the first dose, and the rhythm of each dose becomes predictable within a week.

Days 1–3

First impressions

The immediate-release effect is fairly noticeable from the first dose; you may feel clearer, more able to start tasks, or less overwhelmed by mental noise. Appetite often drops straight away. Some people feel slightly wired or jittery on day one; this usually settles quickly.

Week 1

Settling in

Effects become more predictable. You'll start to notice the rhythm of each dose: when it kicks in, when it peaks, and when it wears off. The wearing-off (rebound) effect is noticeable for many people in the first week: a mood dip or irritability as a dose clears. Track when it happens and mention it at your review.

Weeks 2–3

Finding your rhythm

Most early side effects (headache, nausea, dry mouth) settle by now. You and your prescriber will be refining the timing and number of doses. The rebound often becomes more predictable and easier to plan around once you know your pattern.

At target dose

Established effect

Consistent focus during each dose window. It shouldn't feel like a different you: more like tasks that were always hard becoming slightly more accessible. Multiple doses give your prescriber more levers to adjust if anything isn't quite right.

Section 5

What are the side effects of dexamfetamine?

The most common early side effects are reduced appetite, difficulty falling asleep, dry mouth and mild headaches. Most settle within 1–2 weeks.

All expanded by default: tap a category to collapse it. Most of these ease in the first 1–2 weeks.

Reduced appetite during the day

Very common

What helps

  • Eat a substantial breakfast before the first dose takes effect.
  • Appetite usually returns in the evening: plan your main meal for then.
  • If you can, prepare it earlier in the day, while the medicine is working.
  • Balanced ready-to-heat meals (freshly made, not processed microwave meals) save the planning that stops many people eating.
  • Small snacks count if you can't manage more.
  • Tell your prescriberTalk to your prescriber within a few days if weight loss is becoming significant.

Nausea, particularly in the first week

Common

Most common in the first week or two.

This usually settles within 7–10 days.

What helps

  • Take your doses with or just after a meal; ginger tea or plain crackers help.
  • Drinking enough water and eating regular, smaller meals may help.

Mood dip, irritability, or tiredness as a dose wears off

Common

This is a predictable feature of short-acting stimulants: as each dose clears, dopamine activity drops briefly.

You may feel more irritable, flat, or emotionally sensitive for 30–60 minutes.

  • Tell your prescriberTrack when it happens and mention it at your review: timing adjustments or changes to the dose schedule often help.

Difficulty falling asleep

Very common

What helps

  • The cut-off for your last dose is the main lever.
  • Most people need the last dose at least 4–6 hours before bed.
  • Try the interactive dexamfetamine duration & effect chart to see how the timing of each dose affects when it wears off.
  • Cut down on caffeine, especially after midday: it often makes stimulant side effects worse.
  • Tell your prescriberStill struggling after 2–3 weeks of timing adjustments? Tell your prescriber: disrupted sleep undermines everything the medication is trying to do.

Feeling tired when a dose wears off

Common

The wearing-off effect can include fatigue and low energy.

It becomes easier to manage once you know your pattern.

What helps

  • Plan lower-demand activities for these windows.

Anxiety, agitation, or irritability

Common

A dose reduction sometimes resolves persistent anxiety.

What helps

  • Note when it happens.
  • As a dose kicks in: take your doses with or just after meals, if you do not already.
  • During peak hours: may be dose-related.
  • Between doses or in the evening: likely rebound.
  • Good sleep, regular meals, less caffeine and staying hydrated all help.

Feeling emotionally flat or unlike yourself

Frequency not known

Some emotional calming is expected.

  • Tell your prescriberIf it feels like your personality is muted, raise it at your next review: it's usually dose-related and resolves with adjustment.

Headaches, particularly in the first 1–2 weeks

Common

Most common early in treatment and often eases.

What helps

  • Drinking enough water and eating regular meals may help: set reminders if you forget to drink.
  • Paracetamol can usually be taken alongside dexamfetamine.
  • Check with a pharmacist first if you have other health conditions or take other medicines.

Dry mouth

Common

What helps

  • Sip water regularly.
  • Sugar-free gum or mints can help.
  • Keep brushing twice a day and keep up dental check-ups.
  • Tell your prescriberMention it at your review if it bothers you or is severe.

Abdominal pain or stomach discomfort

Common

What helps

  • Keep fluid intake up.
  • Taking doses with food can help.
  • Tell your prescriberMention persistent symptoms at your next review.

Mildly increased heart rate or blood pressure

Common

A small rise in pulse and blood pressure is an expected effect of dexamfetamine.

That is why your prescriber checks them before you start, after each dose change and at least every 6 months.

What helps

  • Cut down on caffeine and avoid cold and flu remedies that contain a decongestant.
  • Keep salt and alcohol down, and keep up regular moderate exercise.
  • Tell your prescriberTell your prescriber within a few days if your resting pulse stays above 100. The same if your blood pressure stays at 140/90 or higher (135/85 at home).
  • Get help todayA reading of 180/120 or higher after 5 minutes' rest, or a resting pulse above 120: contact your prescriber or 111 today.

Palpitations

Common

Brief, mild awareness of your heartbeat is common in the first few weeks.

What helps

  • Reduce caffeine and stay hydrated.
  • Get help todayContact your prescriber if your heart races or pounds at rest, or if palpitations come with dizziness or breathlessness.

This is the full list for this guide, including uncommon and rare effects. For step-by-step tips on managing the common ones, and when to speak to your prescriber, see Dexamfetamine side effects: what helps.

Section 6

When should I get help while taking dexamfetamine?

Call 999 for severe or spreading chest pain, severe breathlessness, sudden weakness, numbness or difficulty speaking, a first seizure or a suspected overdose. Call 999 too for a severe allergic reaction: sudden swelling of the lips, mouth or throat, or difficulty breathing. Seek urgent help for mild chest pain or an irregular heartbeat, hallucinations, or thoughts of self-harm (call 999 if you might act on them).

Emergency: call 999 or go to A&E

  • Severe chest pain, or chest pain spreading to your arm, jaw or back
  • Severe shortness of breath or struggling to breathe
  • Sudden weakness, numbness, difficulty speaking, or confusion: call 999 immediately
  • A first seizure (no previous history of seizures)
  • Suspected overdose
  • Thoughts of harming yourself or someone else that you feel you might act on, or you have harmed yourself
  • Severe allergic reaction (anaphylaxis): sudden swelling of the lips, mouth, throat or tongue, or difficulty breathing or swallowing. Call 999.
No action

Expected adjustment effects

Common in the first few weeks: no action usually needed

  • Reduced appetite through the day
  • Mild headaches, particularly in week one
  • Dry mouth
  • Nausea in the first week or two
  • Mood dip or irritability for 30–60 minutes as a dose wears off
  • Feeling slightly quieter or more focused
  • Brief, mild awareness of your heartbeat
  • Mild difficulty falling asleep while still refining dose timing
Contact prescriber

Contact your prescriber within a few days

Not urgent: but worth discussing if ongoing

  • Rebound mood dips that significantly affect your evenings or relationships
  • Sleep problems that haven't improved after 2–3 weeks of timing adjustments
  • Significant unintended weight loss or consistently unable to eat enough
  • Feeling emotionally flat or unlike yourself
  • Persistent anxiety, agitation, or jitteriness
  • Blood pressure consistently higher than your normal baseline
  • Tics or twitching that are new or worsening
  • Fingers or toes going pale, numb, or blue in the cold
  • Persistent headaches beyond the first two weeks
Urgent

Contact your prescriber or 111 today

Do not wait for a routine appointment

  • Mild chest pain or tightness, or an irregular heartbeat
  • Signs of very high blood pressure (severe headache, vision changes, confusion)
  • Hallucinations or loss of touch with reality
  • Thoughts of self-harm or suicide
  • A new rash, without swelling or breathing problems

What you can safely try while waiting for a review

  • Drink enough water through the day: it may help with headaches and a dry mouth
  • Eat breakfast before your first dose: food before appetite suppression kicks in makes a real difference
  • Move your last dose earlier if sleep is the issue
  • Move your doses slightly earlier overall if the rebound is hitting at a bad time
  • Keep a brief daily note of symptoms, timing, and mood: invaluable at reviews
  • Reduce caffeine, especially after midday
  • Plan lower-demand activities for the times when doses wear off
  • Paracetamol can usually be taken for headaches: check with a pharmacist if you have other health conditions or take other medicines
Section 7

Frequently asked questions about dexamfetamine

What's the difference between dexamfetamine and Elvanse?

They're the same active ingredient: dexamfetamine. The difference is delivery. Elvanse is a prodrug: it's inactive when you swallow it, and your red blood cells slowly convert it to dexamfetamine over a few hours, producing a smooth effect that lasts up to 14 hours from a single morning dose. Dexamfetamine tablets are already active; they work faster but wear off sooner (3–6 hours per dose), which is why you need to take them more than once a day. Neither is better; they suit different needs.

Why do I need to take it more than once a day?

Because each dose only lasts 3–6 hours. To cover a standard working day, you typically need a morning dose, a midday dose, and sometimes a third dose in the early afternoon. Your prescriber will work out the right pattern for your day; you might not need all three doses every day.

What is the wearing-off or rebound effect?

As each dose clears your system, dopamine activity drops. For 30–60 minutes after a dose wears off, you may feel more irritable, flat, or emotionally sensitive than usual. This is a predictable feature of short-acting stimulants, not a sign of dependence or addiction. It's most noticeable in the evening after the last dose. Tracking when it happens and mentioning it at your review helps your prescriber adjust timing.

Can I drink alcohol while taking dexamfetamine?

Best advice: avoid it entirely.

Dexamfetamine and alcohol push your heart harder together than either does alone. You may notice a faster heart rate, palpitations, and higher blood pressure.

Alcohol also hides the stimulant effect. That means you can drink far more than you planned without feeling it.

Alcohol can also make some side effects worse. If you do drink, keep it to an absolute minimum and tell your prescriber.

Will I become dependent on it?

Physical dependence: where your body adapts to expect the medication: can develop with long-term use, but this is not the same as addiction. People with ADHD generally don't develop compulsive drug-seeking behaviour at therapeutic doses. Take it only as prescribed, at the doses prescribed. Do not share it.

Will it show up on a drug test?

Yes: dexamfetamine will produce a positive result for amphetamines on any standard drug test: urine, saliva, or blood. This applies to workplace, legal, sporting, and roadside tests. Carry your prescription or a letter from your prescriber. The law provides a statutory medical defence for roadside tests if you are taking a prescribed dose and are not impaired.

Can I skip doses on days when I don't need them?

Yes: some people choose not to take all doses at weekends or during lower-demand periods. There is no medical requirement to take every scheduled dose, and this can help with appetite and sleep on quieter days. Discuss this pattern with your prescriber. Do not change your overall prescribed dose without speaking to them first.

What happens when I stop?

If you stop suddenly after long-term use, you may feel temporarily tired, low in mood, or notice increased appetite; this reflects your brain readjusting. These effects are usually short-lived. Do not stop suddenly without speaking to your prescriber first: a gradual reduction is usually recommended.

My prescription says 'dexamfetamine sulfate': is that the same thing?

Yes. Dexamfetamine sulfate is the active ingredient. It may be dispensed as a generic tablet or as the brand Amfexa (5 mg, 10 mg, and 20 mg tablets). A liquid formulation is also available (5 mg/5 mL oral solution).

What if I also take Elvanse? Can I have both?

Some people are prescribed Elvanse for daytime coverage and a small dose of dexamfetamine as a booster to extend the effect into the early evening. This is a recognised clinical approach: your prescriber will advise if it's appropriate for you.

What about pregnancy and breastfeeding?

Pregnancy: Speak to your prescriber before becoming pregnant if possible, or as soon as you know you are pregnant. Current evidence (BUMPS) suggests dexamfetamine may affect a baby's growth and can increase the risk of early birth. If taken in the third trimester, your baby may experience temporary withdrawal symptoms after birth: excessive crying, irritability, and unsettled behaviour. These usually resolve within a few days. Do not stop suddenly without speaking to your midwife, GP, or specialist first.

Breastfeeding: Dexamfetamine can be used with caution (Breastfeeding Network). If your baby is younger than 6–8 weeks or you are exclusively breastfeeding, methylphenidate is generally the preferred option as it is better studied in this context. If you continue dexamfetamine while breastfeeding, use the lowest effective dose and monitor your baby for changes in appetite, sleep, or irritability. You do not need to stop breastfeeding automatically: discuss the specifics with your prescriber.

Section 8

What should I ask my prescriber about dexamfetamine?

Questions worth raising at your next review. You don't need to cover all of them: pick the ones that feel most relevant.

  • Are there any monitoring checks I'm due: blood pressure, pulse, weight?
  • How long does each dose seem to last: when does it kick in, and when do you notice it wearing off?
  • Are you experiencing any rebound effect between doses or in the evening: and if so, when does it happen?
  • Has your appetite been significantly affected? Are you eating enough through the day?
  • Has your sleep changed since starting? Are you falling asleep within a normal time after the last dose?
  • Is the current number and timing of doses working for your day: or are there gaps in coverage?
  • Am I on the right type of stimulant: could a different formulation suit me better?
  • Are any of my other medicines interacting with dexamfetamine?
  • Are you subject to drug testing at work or for sport?
  • If I want to take a break from the medication, how should I do this safely?
Section 9

Dexamfetamine: notes for GPs and clinicians

For GPs and clinicians

Clinical notes by , ADHD Advanced Practitioner and Clinical Prescribing Pharmacist.

ClinicalLicensing and indication

Dexamfetamine sulfate is not licensed for ADHD in adults in the UK. Adult use is off-label but explicitly supported by NICE NG87. Prescribers should document the off-label rationale and discuss this with the patient. The licensed indication is for children and adolescents aged 6 and over.

ClinicalMechanism: key differences from lisdexamfetamine

Unlike lisdexamfetamine (Elvanse), dexamfetamine is not a prodrug; it is pharmacologically active immediately upon absorption. It acts as a direct releasing agent and reuptake inhibitor of dopamine and noradrenaline at presynaptic neurons. The result is a faster onset (Tmax ~1–2 hours) and shorter duration (3–6 hours) than lisdexamfetamine (12–14 hours). Multiple daily doses are required to provide daytime coverage. The short half-life contributes to the rebound phenomenon: a transient decrease in dopaminergic tone as each dose clears.

ClinicalDosing and titration

Start at 5 mg twice daily. Increase by 5 mg at intervals of at least one week, guided by tolerability and clinical response. Maximum: 60 mg/day in 2–4 divided doses. Last dose should be at least 4–6 hours before bedtime. If tolerability is the limiting factor, smaller increments over a longer titration period are preferable to stopping treatment.

ClinicalSchedule 2 CD and prescribing requirements

Dexamfetamine is a Schedule 2 Controlled Drug. Prescriptions must comply with CD requirements (quantity in words and figures, no repeats). Maximum 30 days' supply per prescription. Cannot be prescribed on FP10MDA (instalment) forms for ADHD.

ClinicalAlcohol interaction

Alcohol has additive effects on the cardiovascular system when combined with dexamfetamine: increasing the risk of elevated blood pressure, palpitations, and cardiovascular strain. Alcohol also masks signs of intoxication, leading to unintentional excess consumption. Clinical guidance (SCP) recommends avoiding alcohol entirely during treatment. This is a stronger recommendation than the general caution that applies to methylphenidate.

ClinicalDrug interactions

MAOIs: absolute contraindication: do not prescribe within 14 days of stopping an MAOI; risk of hypertensive crisis. SSRIs and SNRIs: concurrent use is generally manageable but requires monitoring for serotonin syndrome (agitation, tachycardia, tremor, hyperthermia). Alkalinising agents (antacids, sodium bicarbonate): may increase amphetamine absorption. Urinary acidifying agents (including high-dose vitamin C): reduce efficacy by increasing renal excretion. Blood pressure medications: dexamfetamine may reduce their effectiveness.

ClinicalTics and Tourette's syndrome

Tics are listed as a contraindication in the SCP but BNF recommends caution rather than absolute exclusion. Assess pre-treatment; take a personal and family history of tics. The global clinical rule applies: caution requiring assessment and monitoring: not an absolute contraindication. If tics develop or worsen after initiation, review dose and consider alternatives.

ClinicalRenal and hepatic impairment

No manufacturer dose guidance is available for either. Renal impairment: apply 'start low, go slow' with closer monitoring; document the decision. Hepatic impairment: consider hepatic function before initiating and monitor more closely.

ClinicalStopping dexamfetamine

The Amfexa SmPC (section 4.2) states that a gradual reduction of the dose and careful monitoring are required when discontinuing; section 4.4 notes that abrupt withdrawal after a prolonged period of high doses may cause extreme fatigue. Review the indication for discontinuation, dose, duration of exposure and current mental state. Counsel about recurrence of ADHD symptoms and possible fatigue, low mood or appetite changes, and agree an individual reduction and monitoring plan. Avoid categorical statements that dependence, tolerance or withdrawal effects cannot occur.

ClinicalPregnancy and breastfeeding

Pregnancy: BUMPS is the primary patient-facing source. Current evidence suggests potential effects on fetal growth and increased risk of preterm delivery. If used in the third trimester, neonatal withdrawal symptoms are possible. The decision to continue, switch, or stop should involve specialist input.

Breastfeeding: BfN April 2025 guidance applies. Dexamfetamine is not as well studied as methylphenidate during breastfeeding. Use with caution. For babies aged 6–8 weeks or younger, or where breastfeeding is exclusive, methylphenidate is the preferred stimulant. Monitor infant for changes in appetite, sleep, and irritability. Breastfeeding does not need to stop automatically.

This guide is written for educational purposes and does not constitute medical advice. Always follow the guidance of your prescriber or pharmacist. If you have concerns about your medication, contact your clinical team.

Sources

About this guide

Written and clinically reviewed by
ADHD Advanced Practitioner and Clinical Prescribing Pharmacist
First published
Last updated
Last reviewed
Next review
What changed
October 2026: clearer advice on when to call 999 (severe or spreading chest pain, severe breathlessness, or thoughts of self-harm you might act on) and when to get help the same day. Side effect frequencies now use the categories in the product information (SmPC). Food advice: with or without food, but preferably with or just after meals. The headache advice now says drinking enough water may help, instead of naming dehydration as the cause. Paracetamol can usually be taken, but check with a pharmacist if you have other health conditions or take other medicines. The heart-rate advice now explains the monitoring instead of saying a rise is not dangerous. The amber and red help tiers now read "within a few days" and "today". 21 October 2026: the clinician note on stopping no longer says no taper is required or that symptoms are not signs of dependence.

“Last updated” is when the content last changed. “Last reviewed” is when it was last checked against current sources.

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