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Modafinil for the treatment of narcolepsy

What is narcolepsy?

Narcolepsy is a long-term condition which causes excessive sleepiness during the day and may disrupt your sleep at night. You can also have sleep attacks where you fall asleep at inappropriate times during the day without any warning.

What is modafinil?

Modafinil is a type of medicine called a stimulant. It can be used to treat some of the symptoms of narcolepsy. Although there is no cure for narcolepsy, modafinil can help to control your symptoms. Modafinil works by stimulating your brain to increase alertness and reduce excessive sleepiness during the day.

How do I take the medicine?

Modafinil should be swallowed with a drink of water, and can be taken with or after food. Do not break or crush the tablet.

Take modafinil exactly as your consultant or pharmacist tells you to. There are 2 strengths of tablet available, in 100mg and 200mg.

When you start modafinil you might be prescribed a dose of 50mg to 100mg a day. Then, once your body is used to it, increased to 200mg a day. You may be asked to take this as 1 dose of 200mg in the morning, or in 2 doses of 100mg in the morning and at 12 noon. Your consultant or pharmacist will tell you which is right for you.

Your dose may be increased after a little while, depending on your symptoms.

What should I do if I forget to take the medicine?

Don’t worry. Just remember to take the next dose when it is due.

Do not take 2 doses together to make up for the forgotten dose.

Are there any side effects?

Lots of medicines can cause unwanted side effects, although not everyone gets them. The following are examples of some of the side effects reported by patients taking modafinil. The unwanted effects often fade as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Side effect

What can I do about this?

Very common (more than 10 percent)

Note: if you are prone to migraines, taking modafinil may increase how often you get them and their severity.

This usually passes within a day or so. Drink plenty of water and some painkillers, for example, paracetamol.

If the headache continues, speak with your consultant or GP.

Common (between 1 percent and 10 percent)
Dry mouth Try chewing sugar-free gum or sugar-free sweets.
Feeling or being sick


Stomach ache

Stick to simple meals. Avoid rich or spicy foods.
Diarrhoea Drink plenty of water to replace lost fluids. Stick to bland foods including bananas, white rice, apple sauce and toast.
Constipation Try to eat a well-balanced diet and drink several glasses of water each day.
Feeling dizzy or tired

Blurred vision

Do not drive or use tools or machinery until you feel better. Sleepiness associated with your condition can make this worse.

Loss of appetite


Difficulty sleeping


Depression, confusion or confused thinking

Numbness or tingling feelings

Speak to your GP if any of these continue or become troublesome.

For further information on side effects, please see the manufacturer’s leaflet that comes with the medicine.


If you experience any of the following symptoms, contact your GP for advice as soon as possible:

  • a rash or blisters on the skin
  • any changes to your mood, behaviour, or thinking
  • chest pain, fast heartbeat, or unexplained breathlessness
  • any suicidal thoughts, or thoughts about harming yourself

Can I take modafinil with other medicines?

Modafinil may interact with some medicines. It is important to let us know about any medicines that you are currently taking, so that we can check modafinil is suitable for you. If you are buying any medicines over the counter from a pharmacy, always mention that you have been prescribed modafinil.

It is safe to take paracetamol and ibuprofen with this medicine.

Seek advice when buying herbal or homeopathic remedies.

How will my treatment be reviewed?

Your treatment will be reviewed regularly in the narcolepsy clinic. We can adjust your doses to help with your symptoms. Your consultant will want to check to make sure that the treatment is helping. You may need to have your blood pressure and heart rate checked regularly.

How do I get a repeat prescription?

Your GP will give you a repeat prescription for modafinil. Please make sure you request your repeat prescription early to prevent you running out or risk missing any doses of your medication.

If your GP won’t supply your modafinil, your consultant will provide repeat prescriptions. These will be sent in the post.

You can also go to the Rowland’s pharmacy at Sheffield Children’s Hospital outpatients. To ask them any questions, please call 0114 305 3367.

Is there anything else I need to know?

Hormonal contraceptives

Hormonal contraceptives including:

  • oral contraceptive pills
  • implants
  • intrauterine contraceptive devices (IUCDs)
  • contraceptive patches

are less effective when used with modafinil so you should not use both at the same time. Speak to your GP or consultant about which contraceptive methods are suitable for you while you are taking modafinil.


If you are old enough to drive, you must let the Driver and Vehicle Licensing Authority (DVLA) know if you are diagnosed with narcolepsy.

You may be allowed to drive again when your symptoms are well controlled with medication, but you will need to have regular reviews. Your consultant will advise you about this.

If you are a driver, please be aware that modafinil may 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, if you drive, you should carry some evidence with you which shows that the medicine has been prescribed for you. A repeat prescription form or the information leaflet from the packet is generally enough.

Pregnancy and breastfeeding

You should not take modafinil if you are pregnant. You may need to have a test to double check you are not pregnant before starting modafinil.

If you are sexually active, you should use effective contraception during treatment and for 2 months after it is stopped. If you are considering becoming pregnant or you discover that you are pregnant, you should contact your consultant as soon as possible so that a management plan can be agreed.

Modafinil should not be used if breastfeeding.

Sleep routines

Taking modafinil is not a replacement for a good sleep routine. It is still important to aim to get around 9 to 11 hours of sleep at night, depending on your age. Try to go to bed when you’re tired and get up at about the same time each day.


If you are having an operation or dental treatment, tell your consultant or GP who will be able to advise you further.

Drinking alcohol

Do not drink alcohol while taking modafinil as they can enhance each other’s side effects, such as increased dehydration.

Modafinil should be kept out of reach of children. If anyone other than you takes this medicine, you, they, or their parent or carer should contact NHS 111 for advice. If they are unwell they should call for an ambulance.


Do not use the medicine after the expiry date.

The expiry date is printed on the container. Any that have gone out of date should be returned to your local pharmacy to be properly disposed of.

Contact us

Medicines Helpline

If you have any questions or concerns about your medicines, please speak to the staff caring for you or call our pharmacy helpline.

Narcolepsy team secretaries

0114 271 7400 between 9am to 5pm, Monday to Friday.

Rowland’s Outpatient pharmacy

0114 305 3367 between 9am to 5pm, Monday to Friday.

Your comments and concerns

For advice, support or to raise a concern, contact our Patient Advice and Liaison Service (PALS) on 0114 271 7594 or email scn-tr.pals@nhs.net.
To make a complaint, contact the complaints department on 0114 271 7194.

Other resources

Narcolepsy UK
You might find this charity’s website useful for connecting with patients who suffer from the same condition as you, but any information found should not alter your current treatment. You should discuss any new advice with the doctor caring for your condition.

NHS 111
Offers medical help and advice from fully trained advisers supported by experienced nurses and paramedics. Available over the phone 24 hours a day on 111.

Provides online information and guidance on all aspects of health and healthcare, to help you make choices about your health.


Reproduced with kind permission of Guy’s and St Thomas’ NHS Foundation Trust.

Is something missing from this resource that you think should be included? Please let us know

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Please note: this is a generic information sheet relating to care at Sheffield Children’s NHS FT. These details may not reflect treatment at other hospitals. This information is not intended as a substitute for professional medical care. Always follow your healthcare professionals’ instructions. If this resource relates to medicines, please read it alongside the medicine manufacturer’s patient information leaflet. If this information has been translated into another language from English, efforts have been made to maintain accuracy, but there may still be some translation errors. If you are unsure about any of the guidance in this resource or have specific questions about how it relates to your child, always ask your healthcare professional for further advice.

Resource number: SLP28

Resource Type: Article

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