modafinil at a glance
Medicine class
Centrally acting wakefulness-promoting agent.
Licensed use
Excessive sleepiness associated with narcolepsy in adults, with or without cataplexy.
Administration
Oral tablet; swallow with water. Food may delay absorption but does not reduce overall absorption.
Monitoring
Heart rate, blood pressure, mental health and continuing sleepiness require review.
What is modafinil used for?
The selected UK product is licensed for adults with excessive sleepiness associated with narcolepsy.
Narcolepsy with cataplexy.
Narcolepsy without cataplexy.
How does modafinil work?
Its precise wake-promoting mechanism is not fully established. It blocks dopamine reuptake and has weaker effects on noradrenaline uptake, influencing brain networks involved in arousal, vigilance and the sleep–wake cycle.
modafinil preparations and strengths
Tablet
Route: Oral
Strengths: 100 mg, 200 mg
How to take modafinil
Follow the dispensing label and prescriber's instructions. Swallow tablets with water, with or without food. Maintain good sleep habits because modafinil is not a substitute for sleep.
The selected score-marked tablet can be divided into equal halves when instructed.
Review caffeine intake if treatment is worsening insomnia.
Do not drive or use machinery if you remain sleepy, dizzy or have blurred vision.
modafinil side effects
Common or expected effects
- Headache
- Reduced appetite
- Nervousness, anxiety or irritability
- Difficulty sleeping
- Dizziness or sleepiness
- Palpitations or faster heartbeat
- Nausea, abdominal discomfort, dry mouth, indigestion, diarrhoea or constipation
- Blurred vision
Get urgent medical advice
- New rash, blistering, peeling, mouth or eye ulcers, or fever with rash
- Facial or throat swelling, wheezing or difficulty breathing
- Suicidal thoughts, severe depression, aggression or marked behavioural change
- Hallucinations, delusions, mania or psychosis
- Chest pain, significant blood-pressure rise or irregular heartbeat
- Fever and rash with swollen glands or signs of liver, blood or other organ involvement
modafinil in pregnancy
Modafinil should not be used during pregnancy because human reports suggest a possible increased risk of major congenital malformations. Contact the prescriber promptly if planning pregnancy or if pregnancy occurs. Effective contraception is required during treatment and for two months after stopping because modafinil can make many hormonal contraceptives less effective.
modafinil while breastfeeding
The selected UK product states that modafinil should not be used while breastfeeding. Animal data show transfer into milk and adequate human safety evidence is unavailable; discuss feeding or treatment alternatives with the specialist prescriber.
modafinil interactions
Modafinil can change the effectiveness or exposure of other medicines. Check prescribed, pharmacy and herbal products before use.
Hormonal contraceptives
May reduce contraceptive effectiveness. An appropriate alternative or additional method is required during treatment and for two months afterwards.
Warfarin
Clearance may decrease, requiring closer clotting-time monitoring when modafinil is started, changed or stopped.
Phenytoin
Exposure may increase; monitor for toxicity and consider checking blood concentrations.
Common questions about modafinil
Answers are fully visible for fast scanning and source review.
What is modafinil used for?
It is licensed to treat excessive sleepiness in adults with narcolepsy, with or without cataplexy.
Does modafinil cure narcolepsy?
No. It can improve daytime wakefulness and reduce sleep attacks, but some sleepiness may continue.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.