Atomoxetine (Strattera)
Atomoxetine hydrochloride
Overview
Medication class
A non-stimulant ADHD medication: the only one of its kind licensed specifically for ADHD in UK adults.
When it's prescribed
Often recommended when stimulants have not worked or aren't suitable: or when a non-controlled-drug option is preferred. Also has positive evidence in ADHD with anxiety.
Typical duration
24 hours, once your body reaches steady state (usually after 1–2 weeks of daily use). No on/off effect. No rebound in the evening.
Available strengths
Hard capsules: 10mg, 18mg, 25mg, 40mg, 60mg, 80mg, 100mg. Oral solution (4mg/mL) available if you can't swallow capsules.
Key advantages
- NOT a stimulant: completely different mechanism from methylphenidate or Elvanse
- NOT a controlled drug: standard repeat prescription from your GP
- 24-hour steady coverage: no gap in the afternoon or evening, no rebound
- Works overnight too: no ADHD symptom 'holiday' at the weekend
- No misuse potential: not euphoric, not addictive
- Positive evidence when anxiety and ADHD occur together
- Better sleep profile than most stimulants: less likely to affect your ability to get to sleep
- No positive result on standard workplace or forensic drug tests
Key cautions
- Takes weeks to work; this is not a medication you'll feel kicking in on day one
- Must be taken every day; it doesn't work 'as needed'
- Capsules must be swallowed whole: do NOT open them (the powder is an irritant)
- GI side effects (nausea, dry mouth, reduced appetite) are common at the start
- Blood pressure and heart rate are monitored throughout treatment
- Check your other medications: some antidepressants (especially fluoxetine and paroxetine) interact with atomoxetine and need a dose adjustment
How it works
When you have ADHD, two key brain chemicals: noradrenaline and dopamine: aren't doing their job properly in the part of your brain that handles focus, planning, and impulse control (called the prefrontal cortex).
Atomoxetine targets a specific transporter called the NET: the noradrenaline transporter. Think of the NET as a vacuum cleaner that removes noradrenaline from the synapse as soon as it's released. Atomoxetine blocks the vacuum. Noradrenaline builds up, stays in the synapse longer, and starts to reach levels that actually support your brain's executive function.
The same transporter happens to carry dopamine too, in the prefrontal cortex. So by blocking the NET, atomoxetine also raises dopamine levels in that region: even though it has no direct effect on dopamine pathways. This is why it helps with the full range of ADHD symptoms, not just one aspect.
Why does it take so long? Stimulants work by flooding the synapse immediately; you feel them within an hour. Atomoxetine doesn't do that. It works by gradually shifting the baseline level of noradrenaline. That shift takes time. The receptor system in the prefrontal cortex needs to adapt to the new level. This is not a sign the medication isn't working. It is how it works. The effect is building even when you can't feel it yet.
Once atomoxetine reaches steady state in your blood (after 1–2 weeks of daily dosing), it maintains a stable level all day and all night. There is no 'window' when it's active and a window when it isn't. You won't feel it switch off at 6pm.
What atomoxetine doesn't do: it has no stimulant effects; it doesn't cause a 'high' or euphoria; it doesn't affect dopamine in the reward pathways (striatum): only in the prefrontal cortex; it has no serotonin activity; it won't cause a positive result on a drug test for stimulants or any other controlled substance.
Atomoxetine is a selective noradrenaline reuptake inhibitor (SNRI): distinct from the SNRI antidepressants (which also act on serotonin). It has high selectivity for the noradrenaline transporter (NET) with minimal affinity for the dopamine transporter, serotonin transporter, or other neurotransmitter receptors.
Mechanism: Selective NET blockade in the prefrontal cortex (PFC) increases extracellular noradrenaline and, secondarily, dopamine (via NET-mediated dopamine reuptake in PFC, where DAT expression is low). This enhances α2A-adrenoceptor signalling in the PFC: directly improving working memory, inhibitory control, and attentional networks.
Pharmacokinetics: Primarily metabolised by CYP2D6 to 4-hydroxyatomoxetine (active, similar potency). In extensive metabolisers (EM): half-life ~5 hours. In poor metabolisers (PM, ~7% of population): half-life ~22 hours, plasma levels 5–10 times higher. PM status is equivalent clinically to CYP2D6 inhibitor co-administration (e.g. fluoxetine, paroxetine, bupropion).
CYP2D6 interaction: Fluoxetine or paroxetine co-administration inhibits CYP2D6, converting EMs to phenotypic PMs: increasing AUC 5–7 fold. Start at 40mg and titrate cautiously. Dose ceiling is lower in this context.
MAOI contraindication: Absolute. MAOIs + atomoxetine → severe hypertensive crisis risk. 14-day washout from MAOI before starting atomoxetine.
Liver toxicity: Rare cases of severe hepatotoxicity reported post-marketing. Clinically significant jaundice or liver enzyme elevation warrants immediate discontinuation. Do not rechallenge.
Priapism: Rare but documented. Noradrenergic mechanism in erectile tissue. All patients should be counselled at initiation: erection >2 hours = emergency presentation.
AUDS evidence: Positive RCT data for atomoxetine reducing heavy drinking days in adults with comorbid ADHD and alcohol use disorder (AUD). Relevant for shared prescribing decisions.
How to take it
When to take it
Once daily, at roughly the same time each morning. Or, if your prescriber has recommended it, split into two doses: one in the morning and one in the late afternoon or evening. Because atomoxetine is not a stimulant, you can take an evening dose without it affecting your sleep. The 24-hour mechanism means that even taking it at different times of day won't cause a late-night stimulant effect.
Taking it with food
You can take atomoxetine with or without food. The total amount absorbed stays the same either way. Taking it with a meal or a snack is recommended: especially at the start: because it can reduce the nausea that some people experience in the early weeks. The meal slightly reduces the peak concentration, which may ease GI side effects without reducing overall effectiveness.
Swallowing the capsule
Swallow the capsule whole with water. Do NOT open, crush, or chew the capsule. This is different from some other ADHD medications (such as Elvanse, which can be opened into water). Atomoxetine capsules contain a powder that can irritate the skin, eyes, and mouth if it comes into contact. If a capsule is accidentally damaged, avoid touching the powder and wash any contact area thoroughly with water. If you cannot swallow capsules at all, tell your prescriber: an oral solution (4mg/mL) is available.
Your dose
Doses are set based on your body weight and how you respond. Adults weighing 70kg or more: Starting dose (for at least 7 days) = 40mg once daily. Standard maintenance = 80mg once daily. Maximum licensed dose = 100mg/day. Adults weighing less than 70kg: Your prescriber will calculate your dose based on your weight. You'll typically start at 0.5mg/kg/day and work up to 1.2mg/kg/day. Dose increases are made at intervals of at least 7–14 days. Don't be tempted to increase faster: your body needs time to adjust at each level.
Missed doses
Take it as soon as you remember: unless it's nearly time for your next dose, in which case skip it and carry on as normal. Never take two doses to make up for a missed one. Occasionally missing a dose won't cause a rebound or crash. But because the medication works by maintaining a steady level, consistent daily dosing gives you the best results.
Do I take it every day: including weekends?
Yes. Atomoxetine needs to be taken every day to maintain its steady-state level. Unlike stimulants, which some people take 'medication holidays' from, atomoxetine doesn't work that way: missing a few days reduces your coverage and can mean it takes time to build back up.
What to expect: week by week
Medication present, results not yet visible
The medication is in your system from day one. Most people notice little change in ADHD symptoms yet. You may notice side effects: nausea, reduced appetite, dry mouth. These are most prominent now. This is completely normal.
Reaching steady state
The medication is reaching steady-state. Some people begin to notice small shifts: slightly less reactive emotionally, a bit more able to follow a thought through. GI side effects usually starting to ease.
First real improvements for most
Around here is when most people who will respond notice their first real improvement. About 47% of eventual responders notice something by week 4. Don't be discouraged if you haven't felt it yet: you're still well within the expected window.
Main review point
The main clinical check-in point. By now, around three quarters of eventual responders have responded. If there's no improvement at a therapeutic dose, your prescriber will reassess. If your prescriber is monitoring your response, they may have increased your dose around weeks 6–8 if needed.
Continuing improvement
Improvement often continues well beyond week 12. About 85% of eventual responders have responded by week 26; 96% by week 52. Some people find their full benefit only becomes clear after six months to a year. Keep attending reviews: the picture often keeps getting better.
Side effects & what helps
All expanded by default: tap a category to collapse it. Most of these ease in the first 1–2 weeks.
Nausea
About 1 in 4 people (~26%)What helps
Most common in the first 1–3 weeks. Take your dose with a meal or snack; this reduces the peak concentration and usually helps. Usually settles within 2–3 weeks.
Dry mouth
About 1 in 5 people (~20%)What helps
Sip water regularly through the day. Sugar-free gum or mints stimulate saliva. Usually improves after the first few weeks.
Reduced appetite
About 1 in 6 people (~16%)What helps
Common at the start. Usually improves. Your prescriber will monitor your weight at reviews.
Constipation
About 1 in 12 people (~8%)What helps
Drink plenty of water. Increase fibre in your diet. Mention at your next review if persistent.
Stomach pain
About 1 in 14 people (~7%)What helps
Usually related to the early adjustment period. Taking with food helps. Mention at your next review if it doesn't improve.
Insomnia
About 1 in 7 people (~15%)What helps
Less common than with stimulants. In a head-to-head study, people taking atomoxetine fell asleep in an average of 12 minutes vs 39 minutes for methylphenidate. If sleep is affected, mention at your next review.
Fatigue / tiredness
About 1 in 10 people (~10%)What helps
Most common in the early weeks. For most people it improves once steady state is established. If it persists, mention at your next review.
Raised heart rate
CommonWhat helps
Mild increases are a direct effect of how this medication works (noradrenaline affects the cardiovascular system). Your prescriber will check this before you start and at reviews.
Raised blood pressure
CommonWhat helps
Monitored at every review. If you check at home, contact your prescriber if consistently above your baseline.
Palpitations
CommonWhat helps
Brief awareness of your heartbeat can occur. Contact your prescriber the same day if you feel chest pain, a racing or irregular heartbeat at rest, or feel like you might faint.
Dizziness
About 1 in 12 people (~8%)What helps
Usually mild. Stay hydrated. Don't drive while dizzy. Mention at your next review if persistent.
Erectile difficulties
About 1 in 12 people (~8%)What helps
Related to noradrenaline's role in the autonomic nervous system. Often improves over time. Discuss with your prescriber; you don't have to put up with it.
Difficulty passing urine
About 1 in 17 people (~6%)What helps
If urinary symptoms are uncomfortable or not improving, tell your prescriber.
Delayed ejaculation
CommonWhat helps
Often improves over time. Discuss with your prescriber if it's affecting quality of life.
Priapism (erection lasting more than 2 hours)
Rare: but a medical emergencyWhat helps
Go to A&E immediately. Do not wait and see. It doesn't matter whether it is painful or not. Every hour of delay increases the risk of permanent injury.
Irritability
About 1 in 20 people (~5%)What helps
Most people find emotional reactivity improves with atomoxetine. If you feel more irritable, note when it happens and mention at your next review.
Suicidal thoughts (warning)
No more common in adults than placebo (0.11% vs 0.12% in trials)What helps
Atomoxetine carries a regulatory warning about suicidal thoughts (mainly from paediatric data). In adults, the trial data shows this was no more common on atomoxetine than placebo. If you experience new or worsening thoughts of self-harm, contact your care team that day: not because atomoxetine is particularly risky in adults, but because any mental health change during medication adjustment should be assessed promptly.
Headache
CommonWhat helps
Usually settles in the first few weeks. Paracetamol is safe alongside atomoxetine. Drink more water.
Sweating
CommonWhat helps
Mention at your next review if it's affecting daily life.
Hot flushes
CommonWhat helps
Usually mild. Mention at your next review if persistent.
Weight loss
CommonWhat helps
Your prescriber will monitor your weight at reviews.
Raynaud's phenomenon (fingers or toes turning white or blue in cold)
RareWhat helps
Keep your hands and feet warm. Avoiding handling frozen items without gloves. Contact your prescriber if it's frequent or causing distress.
Liver problems
Rare (post-marketing reports)What helps
Signs: yellow skin or eyes, dark urine, severe stomach pain, unexplained nausea. Stop atomoxetine and contact your prescriber urgently if any of these occur. Do not wait.
Acute angle-closure glaucoma
Very rareWhat helps
Sudden eye pain, blurred vision, or seeing halos around lights. Go to the A&E eye unit immediately.
When to seek help
Expected: keep going
Common in the first few weeks: no action usually needed
- Mild nausea in the first 1–2 weeks, especially before eating: take it with food
- Reduced appetite during the day
- Dry mouth: drink water regularly; sugar-free gum helps
- A slight headache in the first few days
- Feeling not much different in the first 1–3 weeks; this is completely normal; the medication takes weeks to build up
- Feeling tired in the first week or two
Mention at your next review
Not urgent: but worth discussing at your next review
- Nausea, reduced appetite, or stomach discomfort that hasn't settled after 3 weeks
- Significant unintended weight loss
- Sleep problems that don't improve after the first few weeks
- Difficulty passing urine or a weak stream that doesn't improve
- Erection difficulties or delayed ejaculation that are bothering you
- Raised blood pressure if you check it at home
- Feeling flat, low, or irritable: especially if this is a change from your usual self
- Headache that isn't eased by paracetamol and water
- Fingers or toes turning white or blue in the cold (Raynaud's)
Contact your prescriber today: don't wait
Do not wait for a routine appointment
- New or worsening thoughts of self-harm or suicide: contact your care team today; if you can't reach them, use the out-of-hours crisis line or call 111
- Yellow skin or eyes, dark urine, severe tummy pain, or unexplained nausea that won't settle: signs of liver problems; stop atomoxetine and contact your prescriber urgently
- Sudden eye pain, blurred vision, or seeing halos around lights: possible acute angle-closure glaucoma; go to the A&E eye unit straight away
- Chest pain or a fast/irregular heartbeat when resting
- A rash spreading rapidly, swelling of the face, or throat tightness: signs of a serious allergic reaction
- A new seizure, or worsening of existing epilepsy
- Sudden weakness, vision changes, or speech difficulty: even if brief
What you can safely try while waiting for a review
- Take your dose with a meal or snack to reduce nausea
- Drink plenty of water throughout the day
- Sugar-free gum or mints help with dry mouth
- Keep a brief weekly note of how things are going: gradual improvement can be easy to miss without tracking
- Don't be discouraged in the first few weeks; the medication takes time to build up
- Take at the same time every day for the most stable coverage
- Paracetamol is safe for headaches alongside atomoxetine
Frequently asked questions
I've been taking it for a week and nothing is happening: is it working?
Probably yes; it just hasn't kicked in yet. A week is very early for atomoxetine. The medication needs several weeks to build up to a level where you'll notice a difference. Around half of people who will eventually respond notice their first real improvement at around 3–4 weeks. Give it at least 12 weeks before you draw any conclusions. In the meantime, keeping a short weekly note of how things are going can help you spot the gradual improvement that might otherwise go unnoticed.
Do I have to have tried stimulants first before I can get atomoxetine?
Not necessarily. In UK practice, atomoxetine is often tried after stimulants: but there are many valid reasons to start with atomoxetine directly. These include: preference for a non-controlled drug, medications that interact with stimulants, specific health conditions, comorbid anxiety, or a history of substance use. Your prescriber will discuss which option makes most sense for your situation.
Can I take it with my antidepressant?
It depends which one. Some antidepressants: particularly fluoxetine (Prozac) and paroxetine (Seroxat): slow down the enzyme that processes atomoxetine. This can cause your atomoxetine level to become 5–7 times higher than expected at a standard dose. This doesn't mean you can't take them together; it means your prescriber needs to know and will start you on a lower dose of atomoxetine. Always give your full medication list before starting. One antidepressant that must never be combined with atomoxetine: MAOIs (e.g., phenelzine, tranylcypromine, or high-dose selegiline). There must be at least 14 days between stopping an MAOI and starting atomoxetine. This combination can cause a dangerous spike in blood pressure.
Will it show up on a drug test?
No. Atomoxetine is not a stimulant and not a controlled drug. Standard workplace, occupational health, or forensic drug screening tests look for controlled substances: and atomoxetine is not one of them. It will not cause a positive result.
I have anxiety as well as ADHD: is it safe for me?
Yes, and there is specific clinical evidence that atomoxetine helps with both. In a large randomised trial, atomoxetine significantly improved anxiety symptoms alongside ADHD symptoms. Some stimulants can worsen anxiety in certain people: atomoxetine doesn't have this profile. Let your prescriber know about your anxiety so they can factor it in.
Does it affect sleep?
Usually not: and often it improves it. In a head-to-head study, people on atomoxetine fell asleep in an average of 12 minutes, compared to 39 minutes for people on methylphenidate. If stimulant medication has been making it hard to get to sleep, this is a real advantage. You can also take an evening dose (if on split dosing) without it disrupting sleep the way a stimulant would.
Can I drink alcohol while taking it?
Alcohol isn't an absolute no with atomoxetine, but there are two things worth knowing. Both alcohol and atomoxetine affect blood pressure: their effects can add together, so heavy drinking can increase cardiovascular strain. Atomoxetine is also processed by the liver, and alcohol adds to the burden on your liver: atomoxetine carries a rare but real risk of liver problems, so heavy alcohol use on top of this isn't a good combination. Moderation is strongly advisable. If you have ADHD and also find alcohol use difficult, tell your prescriber: there's actually some positive evidence that atomoxetine can help reduce heavy drinking days for people with both conditions.
What happens if I miss a dose?
Take it as soon as you remember, unless it's nearly time for your next scheduled dose: in which case skip it and continue as normal. Don't double up. An occasional missed dose won't cause a rebound effect, but consistent daily dosing gives you the most stable coverage.
Do I have to take it on weekends and holidays?
Yes. Atomoxetine works by maintaining a steady level in your system: it's not something you take only on days when you need to focus. Taking 'medication holidays' as some people do with stimulants isn't appropriate with atomoxetine. Daily dosing is what keeps the therapeutic effect stable.
I'm thinking about getting pregnant: what should I know?
Tell your prescriber before stopping or continuing atomoxetine. The current evidence (BUMPS, December 2022) doesn't show that atomoxetine causes birth defects, but the data is limited. If taken close to delivery, a baby may have some withdrawal symptoms (jitteriness, difficulty feeding). Breastfeeding: there is no published human data on atomoxetine in breast milk. There is a risk of drowsiness in your baby and, in some babies, a risk of the medication building up in their system (particularly if your baby processes CYP2D6 slowly). This needs an individual review with your specialist: speak to your prescriber before deciding either way. Do not stop atomoxetine without talking to your prescriber or midwife first.
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.
- Is atomoxetine the right choice for me first, or would a stimulant be better for my situation?
- Do any of my current medications interact with atomoxetine: especially fluoxetine, paroxetine, or bupropion?
- Should I take it once a day or split into two doses?
- What should I do if I get nausea at the start: is there anything that helps?
- What are the signs of liver problems I should watch for?
- What should I do if I think I'm having an erection emergency?
- It's been [X] weeks and I'm not noticing much: is this still within the expected window, or should we consider adjusting the dose?
- Have I had enough time at the right dose, or is there more room to go up?
- Can my GP now manage my prescription on a shared care basis, or does it need to stay with my specialist?
- How long am I likely to need to take this?
- If I decide to stop, is there anything I need to do: or can I just stop?
For GPs & clinicians
Atomoxetine is the only non-stimulant ADHD medication with a specific UK adult ADHD licence. Indicated for ADHD in adults, particularly when stimulants have failed, are contraindicated, or are not preferred. Also has RCT evidence for comorbid anxiety and alcohol use disorder (AUD).
Adults ≥70kg: Start 40mg once daily for ≥7 days. Standard maintenance: 80mg/day. Maximum: 100mg/day. Adults <70kg: Start 0.5mg/kg/day. Target: 1.2mg/kg/day. Maximum: 1.4mg/kg/day or 100mg. Dose increases no sooner than every 7–14 days. Split dosing (e.g. 40mg morning + 40mg evening) can reduce peak-related GI side effects without compromising efficacy. Hepatic impairment: Child-Pugh B → 50% dose reduction. Child-Pugh C → 75% dose reduction. (Documented, dose-adjustment guidance available: unlike MPH/dexamfetamine.) Renal impairment: No dose adjustment required: not primarily renally excreted.
Atomoxetine is primarily metabolised by CYP2D6. CYP2D6 poor metabolisers (PMs, ~7% of population) achieve plasma levels 5–10× higher than extensive metabolisers (EMs) and have a t½ of ~22 hours vs ~5 hours. Fluoxetine and paroxetine are potent CYP2D6 inhibitors: co-administration converts EMs to phenotypic PMs. AUC increases 5–7 fold. In this context, start atomoxetine at 40mg and do not exceed 80mg without clinical justification and monitoring. Bupropion is also a CYP2D6 inhibitor: same caution applies. The clinical implication: standard dosing guidance may overdose patients who are PMs or who take CYP2D6 inhibitors. This is a common source of unnecessary adverse events.
Absolute contraindication. MAOIs + atomoxetine → severe hypertensive crisis. 14-day washout from MAOI before starting atomoxetine. No exceptions.
Same baseline and ongoing monitoring as for stimulants: HR and BP at baseline, each dose change, and at least 6-monthly at stable dose. Contraindications include severe hypertension, symptomatic cardiovascular disease, and severe arrhythmia. Noradrenergic mechanism produces similar cardiovascular signal to stimulants: do not assume non-stimulant = cardiovascular risk-free.
Rare post-marketing reports of severe hepatotoxicity, including fulminant liver failure. Onset variable: weeks to months. Counsel all patients on warning signs: jaundice, dark urine, right upper quadrant pain, unexplained nausea. Confirmed jaundice or significant liver enzyme elevation = stop immediately. Do not rechallenge. Avoid concurrent heavy alcohol use (additive hepatic burden).
Rare but documented; noradrenergic mechanism in penile vasculature. All male patients must be counselled at initiation. Erection >2 hours = medical emergency; go to A&E. Do not observe and wait. Permanent ischaemic injury risk escalates with each hour of delay.
Pregnancy (BUMPS December 2022): No clear evidence of teratogenicity but data limited. Possible transient neonatal withdrawal symptoms if used near delivery (jitteriness, poor feeding). Do not stop abruptly: planned reduction with obstetric/psychiatric input. Manufacturer advises avoidance.
Breastfeeding: No published human data. Rat data shows low milk transfer, but CYP2D6 PM status in infant (relevant in ~7% neonates) could cause drug accumulation. No 'safe' conclusion can be drawn. Requires individual specialist review: do not give standard reassurance. Case-by-case decision with full discussion of risk/benefit.
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.