Dexamfetamine sulfate
Brand: Dexamfetamine
Overview
Medication class
Stimulant: dexamfetamine sulfate (immediate-release amphetamine).
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.
Typical duration
Around 3–6 hours per dose. Multiple doses are needed through the day.
Available strengths
5 mg tablets (generic), Amfexa 5 mg, 10 mg, and 20 mg tablets. Oral solution also available (5 mg/5 mL) for those who cannot swallow tablets.
Key advantages
- 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
Key cautions
- 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
How it works
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.
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.
How to take it
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.
With or without food
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. Taking your first dose with or just after breakfast is a good habit: you've eaten a proper meal before appetite suppression kicks in. 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.
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.
What to expect: week by week
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.
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.
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.
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.
Side effects & what helps
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 commonWhat helps
Eat a substantial breakfast before the first dose takes effect. Plan your main meal in the evening when appetite usually returns. Small snacks count if you can't manage more. Talk to your prescriber if weight loss is becoming significant.
Nausea, particularly in the first week
CommonWhat helps
Take with a small amount of food in the first couple of weeks. Ginger tea or plain crackers help. This usually settles within 7–10 days.
Mood dip, irritability, or tiredness as a dose wears off
CommonWhat helps
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. Track when it happens and mention it at your review: timing adjustments or changes to the dose schedule often help.
Difficulty falling asleep
CommonWhat 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. Still 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
CommonWhat helps
The wearing-off effect can include fatigue and low energy. Plan lower-demand activities for these windows. It becomes easier to manage once you know your pattern.
Anxiety, agitation, or irritability
CommonWhat helps
Note when it happens. During peak hours: may be dose-related. Between doses or in the evening: likely rebound. Good sleep, regular meals, and staying hydrated all help. A dose reduction sometimes resolves persistent anxiety.
Feeling emotionally flat or unlike yourself
Less commonWhat helps
Some emotional calming is expected. If 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
CommonWhat helps
The most common cause is dehydration: stimulants reduce your sense of thirst. Drink 6–8 glasses of water daily. Set reminders if needed. Paracetamol is safe alongside dexamfetamine.
Dry mouth
Very commonWhat helps
Sip water regularly throughout the day. Sugar-free gum or mints stimulate saliva and help.
Abdominal pain or stomach discomfort
CommonWhat helps
Keep fluid intake up. Taking doses with food can help. Mention persistent symptoms at your next review.
Mildly increased heart rate or blood pressure
CommonWhat helps
A small rise is an expected pharmacological effect of stimulant medication. Not dangerous in people with a healthy heart. Your prescriber monitors this at every review. Contact your prescriber if you notice a pounding or racing heartbeat at rest.
Palpitations
CommonWhat helps
Brief, mild awareness of your heartbeat is common in the first few weeks. Reduce caffeine and stay hydrated. Contact your prescriber if your heart races or pounds at rest, or if palpitations come with dizziness or breathlessness.
When to seek help
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 your prescriber at your next review
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
Seek urgent medical advice
Do not wait for a routine appointment
- Chest pain, tightness, or irregular heartbeat
- Severe shortness of breath
- Signs of very high blood pressure (severe headache, vision changes, confusion)
- Hallucinations or loss of touch with reality
- Thoughts of self-harm or suicide
- Seizures (if no prior history)
- Allergic reaction: rash, swelling of face, lips, or throat, difficulty breathing
- Sudden weakness, numbness, difficulty speaking, or confusion: call 999 immediately
What you can safely try while waiting for a review
- Drink more water: dehydration worsens nearly all stimulant side effects
- 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 is safe for headaches if needed
Frequently asked questions
Ask your prescriber
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?
For GPs & clinicians
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.
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.
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.
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.
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.
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.
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.
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.
No formal taper is required in most clinical situations. However, abrupt discontinuation after prolonged use: particularly at higher doses: may be associated with fatigue, low mood, and increased appetite temporarily. These are discontinuation symptoms, not signs of physical dependence. Patients should be counselled on what to expect. Consider a gradual reduction if the patient has been on higher doses for an extended period.
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.