What is modafinil used for?
- Modafinil is prescribed for a condition called narcolepsy. People with narcolepsy feel excessively tired or sleepy during the day and can also fall asleep at inappropriate times without any warning. Modafanil is used to increase wakefulness and daytime alertness in these people.
How does modafinil work?
Modafinil is a type of medicine known as a CNS stimulant. It works by stimulating activity within the central nervous system, ie the brain and spinal cord.
The way in which modafinil improves wakefulness is not yet fully understood, but it is believed to have an effect on several neurotransmitter systems in the brain, mainly in areas of the brain that regulate sleep, wake and alertness.
Modafinil’s mode of action appears to be different to other CNS stimulants, such as the amphetamine group of medicines that are also sometimes used to promote wakefulness. This difference is believed to reduce modafinil’s potential for abuse and dependence, though there may still be a risk of this if modafinil is used long-term.
Modafinil does not cure narcolepsy, it only treats the daytime sleepiness.
How do I take modafinil?
- The modafinil dose your doctor prescribes will vary from person to person. You may be asked to take a dose once a day – in the morning, or twice a day – in the morning and at lunchtime. Always follow the instructions given by your doctor.
- Modafinil tablets should be swallowed whole with a drink of water. They can be taken either with or without food.
- If you forget to take a dose, leave out the missed dose and just take your next dose at your usual time. Do not take a double dose to make up for a missed dose.
What should I know before taking modafinil?
- Taking modafinil is not a replacement for a good sleep routine and it’s important that you still try to get the right amount of sleep every night. Talk to your doctor if you find you have problems sleeping.
- Modafinil may cause dizziness and blurred vision. Don’t use tools or operate machinery until you know how taking modafinil affects you and you are sure that you can do these activities safely.
- In the UK, you are required by law to let the Driver and Vehicle Licensing Authority (DVLA) know if you are diagnosed with narcolepsy. You may be allowed to drive if your symptoms are controlled with medication, but you will need to have regular reviews. Your doctor will advise you about this.
- You may need to have an ECG to check your heart before you start taking modafinil. While you’re taking it your blood pressure and heart rate should be regularly monitored.
- Modafinil should not be used during pregnancy and women who could get pregnant should use a reliable contraceptive method to prevent pregnancy while taking modafinil. However, hormonal contraceptives such as the pill may not be suitable because modafinil makes these less effective. It’s important to discuss your contraceptive options with your doctor before you start taking modafinil. Contraception should be continued for two months after you stop taking modafinil.
- Some people have experienced psychiatric side effects while taking modafinil. If you experience any distressing thoughts or feelings, particularly about suicide or harming yourself, or any changes in your mood or behaviour at any point while taking modafinil, it is important to stop taking it and talk to your doctor.
- If you get a rash while taking modafinil you should stop taking it and consult your doctor.
Who may need a lower modafinil dose or extra monitoring?
- Elderly people.
- People with high blood pressure (hypertension) or heart disease.
- People with kidney or liver problems.
- People with a history of psychiatric conditions, such as psychosis, depression, mania, anxiety, agitation or insomnia.
- People with a history of drug, alcohol or substance abuse.
Who should not take modafinil?
- Children and adolescents aged under 18 years.
- Women who are pregnant or breastfeeding.
- People with an irregular heartbeat (arrhythmia).
- People with uncontrolled moderate to severe high blood pressure (hypertension).
- People with a history of enlargement of a chamber of the heart (left ventricular hypertrophy or cor pulmonale).
- People with a floppy heart valve (prolapsed mitral valve) who have experienced the ‘mitral valve prolapse syndrome’ when taking CNS stimulants in the past (ask your doctor about this if you have heart valve problems).
- People who are allergic to any ingredients of the medicine. Check the ingredients listed in the leaflet that comes with the medicine if you know you have specific allergies or intolerances.
What are the possible side effects of modafinil?
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects known to be associated with modafinil. Just because a side effect is stated here doesn’t mean that all people taking modafinil will experience that or any side effect.
Very common (affect more than 1 in 10 people)
Common (affect between 1 in 10 and 1 in 100 people)
- Fast heart rate and awareness of your heart beat (palpitations).
- Chest pain.
- Feeling weak.
- Pins and needles sensations.
- Blurred vision.
- Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting, indigestion or abdominal pain.
- Dry mouth.
- Reduced appetite.
- Difficulty sleeping (insomnia).
- Nervousness or anxiety.
- Abnormal thinking.
- Alteration in results of liver function tests.
Uncommon (affect between 1 in 100 and 1 in 1000 people)
- Mood swings.
- Weight gain or weight loss.
- Dry eyes.
- Abnormal vision.
- Problems with movement, including twitching or tremor.
- Problems with speech.
- Memory loss.
- Shortness of breath.
- Mouth ulcers.
- Feeling thirsty.
- Skin reactions such as rash or itching (see warning above).
- Muscle or joint pain.
- Raised blood sugar or cholesterol levels.
- Changes in your blood pressure.
- Slow or irregular heart beat.
- Psychiatric reactions (see warning above).
- Decreased sex drive.
If you want any more information about the possible side effects of modafinil you should talk to your doctor or pharmacist, or read the leaflet that comes with the medicine. If you think you have experienced a side effect, did you know you can report this using the yellow card website?
Can I take modafinil with other medicines?
It’s important to tell your doctor or pharmacist if you’re already taking any medicines, including those bought without a prescription and herbal medicines, before you start taking modafinil. Similarly, check with your doctor or pharmacist before taking any new medicines with modafinil, to make sure that the combination is safe.
Modafinil makes the combined contraceptive pill, progesterone-only pill, contraceptive patch, contraceptive implant and contraceptive vaginal ring less effective at preventing pregnancy, because it speeds up the breakdown of the hormones in these contraceptives. Women who are using one of these contraceptives should use an extra method of contraception, such as condoms, to prevent pregnancy while taking modafinil. Often it may be more appropriate to use a different method of contraception altogether, particularly if you’re taking modafinil for more than two months. Whichever method is used, effective contraception should be continued for two months after stopping treatment with modafinil. It’s important to discuss contraception with your doctor before you start taking modafinil.
Modafinil also makes morning after pills containing ulipristal or levonorgestrel less effective, so if you need an emergency contraceptive while taking modafinil you should get advice from your doctor.
Modafinil may also increase the breakdown of the following medicines and so could make these less effective:
- calcium channel blockers
- oestrogens in HRT
- protease inhibitors for HIV infection
- statins for lowering cholesterol
Modafinil may increase the blood level of the following medicines, so you may need a lower dose or extra monitoring if you are taking one of these with modafinil:
- tricyclic antidepressants such as amitriptyline and clomipramine.
People who are taking warfarin to prevent blood clots may need to have their blood clotting time (INR) monitored regularly during the first two months of taking modafinil and after any dose changes.
The antiepileptic medicines carbamazepine and phenobarbital may increase the breakdown of modafinil and make it less effective.
What medicines contain modafinil?
Modafinil is a generic medicine, also available under the brand name Provigil.