Dexamfetamine (Amfexa) side effects
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Duration4 hrs per dose
Onset~20–45 mins
Doses
5mg10mg20mg
Immediate-release dexamfetamine: the same active molecule as Elvanse but absorbed directly. Faster onset, clearer peak, and more noticeable wear-off between doses. Dose timing is critical.
This guide covers common, everyday side effects. See the full list of Amfexa side effects, including rarer ones
What helps
- Your last dose timing is the most important variable: work with your prescriber to find the right cut-off time
- As a guide, avoid dosing after 2–3pm if sleep is affected
- Wind-down routine from 9pm: reduce screens, dim lights, no caffeine after midday
DiscussIf sleep is consistently disrupted, your prescriber may adjust your last dose time or consider a long-acting formulation.
What helps
- Dips between doses are more noticeable with IR than long-acting formulations; this is expected
- A consistent daily schedule helps smooth transitions between doses
- Plan lower-demand tasks around dose change-overs where possible
ExpectedWith IR formulations, predictable energy patterns emerge over time: routine helps significantly.
What helps
- Between-dose rebound is more pronounced with immediate-release than long-acting dexamfetamine
- Track the timing carefully; this helps your prescriber adjust the dose schedule
- If this is significantly affecting daily life, discuss switching to a long-acting formulation
DiscussSignificant between-dose mood dips are a review conversation: dose scheduling or formulation changes often help.
What helps
- Some calming of emotional reactivity is expected and often welcomed
- If you feel too detached or unlike yourself, raise this at your next review
- Dose adjustment or formulation change sometimes resolves this
DiscussFeeling unlike yourself warrants a conversation with your prescriber rather than stopping the medication alone.
What helps
- Eat a good breakfast before your first dose; this is the best appetite window of the day
- With multiple doses across the day, plan meals around dose gaps when appetite returns
- Evening is usually the best window for a larger nutritious meal
DiscussConsistent unintended weight loss or inability to eat enough should be raised at your next review.
What helps
- A modest rise is an expected pharmacological effect of dexamfetamine
- Your prescriber will check blood pressure and pulse at every review
- Not dangerous in people with a healthy cardiovascular system
WatchPounding or racing heartbeat at rest, chest tightness, or sudden dizziness: contact your prescriber promptly.
What helps
- Dehydration is the main cause: stimulants significantly reduce thirst awareness
- Aim for 6–8 glasses of water daily
- Paracetamol is safe alongside dexamfetamine when needed
ExpectedEarly headaches are common and usually resolve in the first 2 weeks.
What helps
- Keep a water bottle with you throughout the day and sip regularly
- Sugar-free gum or mints can help stimulate saliva
- Good oral hygiene matters: dry mouth increases dental risk over time
ExpectedVery manageable with consistent hydration habits.
When to speak to your prescriber
Use this guide for any ADHD medication. When in doubt: always make the call.
Green No action needed
- Reduced appetite during the day
- Mild headache in the first week
- Dry mouth
- Feeling more talkative or energised
- Nausea in the first 1–2 weeks
- Mild sleep difficulty while dose timing settles
- Emotional dip as medication wears off (rebound)
- Some stomach discomfort in the first days
Amber Raise at your next review
- Sleep problems persisting past 2–3 weeks
- Significant weight loss or consistent inability to eat
- Feeling emotionally blunted or not yourself
- Low mood, anxiety, or tearfulness
- Irritability affecting relationships or daily life
- New or worsening tics
- Persistent headaches beyond two weeks
- Anxiety that doesn't settle after week 2
Red Urgent: don't wait
- 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 with no prior history
- Allergic reaction: rash, swelling of face/lips/throat, difficulty breathing
For anything in the red column, or if something just feels very wrong: contact your clinical team or NHS 111 today. In an emergency call 999.
You will never be in trouble for checking.
Info
This guide is for general information only. It does not replace medical advice. Always follow your prescriber or pharmacist. Information is UK-based and aligned with NICE guidelines. © 2026 ADHDnotepad: clinician-authored.