Dexamfetamine for narcolepsy and ADHD
Amfexa
Peer reviewed by Sid DajaniLast updated by Michael Stewart, MRPharmSLast updated 9 Nov 2022
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Dexamfetamine is prescribed both for adults and for children, but for different conditions.
It can affect your ability to perform skilled tasks - if affected do not drive and do not use tools or machines.
Do not stop taking dexamfetamine without speaking with your doctor first. Stopping it suddenly may cause problems.
At a glance
Dexamfetamine is a stimulant medicine available as tablets or oral solution.
It is used to treat narcolepsy in adults and ADHD in children aged 6-18 years.
Take dexamfetamine exactly as your doctor tells you, usually 2-4 doses daily.
Do not drink alcohol or stop taking the medicine suddenly without medical advice.
Common side-effects include nausea, stomach cramps, headache, and sleeping problems.
If you experience side-effects that continue or become troublesome, speak with your doctor.
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About dexamfetamine
Type of medicine | A stimulant |
Used for | Narcolepsy in adults, and attention deficit hyperactivity disorder (ADHD) in children aged 6-18 years |
Also known as (UK) | Amfexa® |
Also known as (USA) | Dextroamphetamine; Dexedrine®, Adderall® |
Available as | Tablets, oral solution; modified-release capsules (in US) |
Narcolepsy is a long-term problem that affects your sleep. You feel excessively tired during the daytime but have disturbed sleep during the night. You can also have sleep attacks where you fall asleep at inappropriate times during the day without any warning. Although there is no cure, medicines can help to control the symptoms. Dexamfetamine works by stimulating the central nervous system to increase your alertness and reduce excessive sleepiness during the day. You can, however, develop tolerance to dexamfetamine, so other medicines for narcolepsy (such as modafinil) are often preferred.
Dexamfetamine is also sometimes used by specialists to treat children with attention deficit hyperactivity disorder (ADHD). ADHD is a fairly common condition that mainly affects a person's behaviour. People with ADHD show persistent restlessness, impulsiveness and/or inattention. Help is given to understand your emotions and behaviours but where this is insufficient, medicines may be prescribed. Other medicines for ADHD are often preferred but where these are unsuccessful, dexamfetamine can be helpful.
Before taking dexamfetamine
Back to contentsSome medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you (or a child in your care) start taking dexamfetamine it is important that your doctor knows:
If you are pregnant, trying for a baby or breastfeeding.
If you have a heart condition, or any problems with your blood vessels.
If you have any problems with the way your kidneys work.
If you have an overactive thyroid gland (hyperthyroidism).
If you have high blood pressure.
If you have had a mental health problem - for example, psychosis or bipolar disorder.
If you have epilepsy.
If you have ever had any uncontrollable movements such as a nervous tic, or if you have a condition called Tourette's syndrome.
If you have raised pressure in your eyes (glaucoma).
If you have ever had a problem with drug or alcohol misuse.
If you have an eating disorder such as anorexia nervosa.
If you have a rare inherited blood condition called porphyria.
If you are taking any other medicines. This includes any medicines which are available to buy without a prescription, as well as herbal and complementary medicines.
If you have ever had an allergic reaction to a medicine.
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How to take dexamfetamine
Back to contentsBefore starting this treatment, read the manufacturer's printed information leaflet from inside the pack. The leaflet will give you more information about dexamfetamine and a full list of side-effects from taking it.
Make sure you take dexamfetamine exactly as your doctor tells you to. Your doctor or pharmacist will tell you how many tablets to take and when to take them. It is usual to take 2-4 doses of dexamfetamine each day. Your dose will be on the label of the pack to remind you.
When starting your treatment your doctor may give you a small dose and then gradually increase it. This allows your doctor to make sure that you have the dose that helps your condition but avoids unwanted side-effects.
It is not important whether you take dexamfetamine before or after food, but try to remember to take your doses at the same times of day, each day. This will help you avoid missing doses. If you do forget to take a dose, do not worry, just remember to take the next dose when it is due. Do not take two doses together to make up for a forgotten dose.
Getting the most from your treatment
Back to contentsKeep the regular appointments with your doctor so your progress can be monitored. Your doctor will want to check to ensure that the treatment is helping. There may also be tests that your doctor wants you to have - this is especially the case for children taking dexamfetamine.
Do not drink alcohol while you are on dexamfetamine. Alcohol will increase the risk of side-effects so it is not recommended.
Before you buy any medicines, check with a pharmacist that they are safe to take with dexamfetamine.
If you are a driver, please be aware that dexamfetamine is likely to affect your reactions and ability to drive. It is an offence to drive while your reactions are impaired. Even if your driving ability is not impaired, should you drive, you are advised to carry with you some evidence that the medicine has been prescribed for you - a repeat prescription form or a patient information leaflet from the pack is generally considered suitable.
If you are due to have an operation, it is important that you tell the person carrying out the treatment that you are taking dexamfetamine.
Taking dexamfetamine can lead to your body becoming dependent on it. Your doctor will discuss this with you before you start treatment.
Do not stop taking dexamfetamine unless your doctor tells you to do so. This is because stopping it suddenly can cause problems and your doctor is likely to recommend that your dose should be reduced gradually.
Additional information if dexamfetamine is for narcolepsy
Have a regular sleep routine. Aim to get around eight hours of sleep at night if possible. You should try to go to sleep and get up at about the same times each day. Some people find that scheduled naps during the day can help to reduce their daytime sleepiness.
In the UK, you are required to let the Driver and Vehicle Licensing Authority (DVLA) know if you are diagnosed with narcolepsy. You should stop driving straightaway, and not drive again until you are permitted to do so by the DVLA.
You should try to avoid heavy meals, as these can make you sleepy. Doing regular exercise may be of benefit and may help your symptoms.
You may find it helpful to tell close friends and work colleagues about your condition. This will help them to understand your symptoms, and there may be help that they can give you, such as help with working schedules.
Additional information if dexamfetamine is for ADHD
There are treatment programmes that will be recommended for you and/or your child. These will provide you with strategies to improve behaviour and reduce any long-term impact.
From time to time your doctor will assess the treatment to make sure it is still required. This may involve stopping dexamfetamine for a short while.
There is a small amount of evidence to show that a change in diet may help some people with ADHD. If you think that diet may be a factor for you or your child, discuss this with your doctor to see if speaking with a dietician might be of benefit.
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Can dexamfetamine cause problems?
Back to contentsAlong with their useful effects, all medicines can cause unwanted side-effects although not everyone experiences them. The table below lists some of the most common ones associated with dexamfetamine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve over the first few days of taking a new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.
Common dexamfetamine side-effects | What can I do if I experience this? |
Feeling sick (nausea), stomach cramps | Stick to simple meals - avoid rich or spicy foods |
Feeling dizzy, eyesight problems | If this happens, do not drive and do not use tools or machines |
Headache | Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know |
Dry mouth, unusual taste | Try chewing sugar-free gum or sucking sugar-free sweets |
Diarrhoea | Drink plenty of water to replace lost fluids |
Sleeping problems, mood changes, feeling unsteady or shaky, lack of appetite, loss of weight, a feeling that your heart is pounding (palpitations), hair thinning, itchy rash, sweating, unusual movements, sexual difficulties | Speak with your doctor about any of these |
If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.
How to store dexamfetamine
Back to contentsKeep all medicines out of the reach and sight of children.
Store in a cool, dry place, away from direct heat and light.
If you are using the oral solution, you should safely dispose of any remaining liquid once the bottle has been open for 30 days. Make a note of the date when you open the bottle.
Important information about all medicines
Back to contentsImportant information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else may have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Report side effects to a medicine or vaccine
If you experience side effects, you can report them online through the Yellow Card website.

Unsure about mixing medicines?
Check for possible interactions between medicines, supplements and foods before taking them together.
Frequently asked questions
Can adults with ADHD use dexamfetamine?
The article states that dexamfetamine is used for ADHD in children aged 6-18 years. It does not mention its use for adults with ADHD.
How does dexamfetamine help with narcolepsy symptoms beyond just keeping me awake?
Dexamfetamine stimulates the central nervous system to increase alertness and reduce excessive daytime sleepiness. It can help control symptoms like feeling excessively tired and reduce the occurrence of sudden sleep attacks.
What should I do if I forget to take a dose?
If you forget a dose, do not worry. Just take the next dose when it is due. You should not take two doses together to make up for a forgotten dose.
Is it possible to become dependent on dexamfetamine?
Yes, taking dexamfetamine can lead to your body becoming dependent on it. Your doctor will discuss this with you before you begin treatment.
Can I stop taking dexamfetamine once I feel better?
You should not stop taking dexamfetamine unless instructed by your doctor. Stopping it suddenly can cause problems, and your doctor will likely recommend reducing your dose gradually.
Are there any specific dietary considerations while taking dexamfetamine for narcolepsy?
Yes, it's advised to avoid heavy meals as they can make you feel sleepy. The article also suggests that regular exercise might help improve your symptoms.
What if I experience side-effects that are not listed in the article?
If you experience any other symptoms that you believe might be caused by dexamfetamine, you should speak with your doctor or pharmacist.
How often will my child's treatment for ADHD with dexamfetamine be reviewed?
Your doctor will periodically assess the treatment to confirm it is still required. This assessment might include temporarily stopping dexamfetamine for a short period.
Further reading and references
- Manufacturer's PIL, Amfexa 5 mg Tablets; Flynn Pharma Ltd, The electronic Medicines Compendium. Dated June 2022.
- Medicines Complete BNF 89th Edition; British Medical Association and Royal Pharmaceutical Society of Great Britain, London.
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About the authorView full bio

Michael Stewart, MRPharmS
Medicine Leaflet Review Manager – Contractor, Pharmacist
BPharm (Hons), MRPharmS
Michael is a community pharmacist practicing in the Midlands and South Yorkshire with more than 20 years’ experience advising on medicines and medical conditions. He has a strong background in healthcare training, having produced and delivered training courses for pharmacy teams and staff of residential care settings, including nurses. He has also contributed to pharmacy advisory boards for the management of low acuity conditions in the community.
About the reviewer

Sid Dajani
Sultan Dajani qualified at the London School of Pharmacy in 1994 and became the youngest elected member of the Royal Pharmaceutical Society council since its founding in 1842.
Article history
The information on this page is written and peer reviewed by qualified clinicians.
Next review due: 8 May 2027
9 Nov 2022 | Latest version

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