Modafinil Dosages: Your GoodRx Guide
Key takeaways:
Modafinil (Provigil) is an oral tablet that treats extreme sleepiness from narcolepsy, sleep apnea, or shift work disorder.
The usual modafinil dosage is 200 mg daily. If you’re taking it for narcolepsy or sleep apnea, you’ll usually take it in the morning. If you’re taking it for shift work disorder, you’ll take it within an hour before your work shift.
If you have severe liver damage or you're older than 65, you may need a lower modafinil dosage. Talk to your healthcare provider about the best dose for your specific situation.
Table of contents
If you have a health condition such as narcolepsy, shift work disorder, or sleep apnea, you may have trouble staying awake. Modafinil (Provigil) is a prescription medication that helps treat extreme sleepiness from these conditions.
The typical modafinil dosage depends on what you’re treating. It’s always best to follow your healthcare provider’s recommendations for how to take it. If you have any questions about your dose, your provider and pharmacist can help guide you.
Keep in mind: Modafinil is a controlled substance. It has a risk of dependence and misuse. But the risk is lower than traditional stimulants used to treat narcolepsy, such as methylphenidate (Ritalin) and dextroamphetamine / amphetamine (Adderall).
What’s the typical modafinil dosage for adults?
Modafinil is available as 100 mg and 200 mg oral tablets. The typical modafinil dosage is 200 mg once daily. But what time of day you should take it depends on what you’re treating.
Good to know: Modafinil isn’t approved for children, so we won’t cover modafinil dosages for children in this article. Although research shows it may be effective for excessive sleepiness, and it’s recommended as one of the only medications to treat narcolepsy in kids, more research is needed. If your child has narcolepsy and you’re wondering whether modafinil could work for them, discuss the risks versus benefits with their provider.
Narcolepsy
Narcolepsy is a sleep disorder where you feel excessively sleepy during the day. Modafinil is a first-choice option for treating narcolepsy.
You’ll most likely take modafinil when you first wake up. This helps address daytime sleepiness that’s common with narcolepsy. It also helps you avoid trouble sleeping (insomnia) at night, since you’re taking it many hours before you go to sleep.
Some research shows that modafinil dosages higher than 200 mg once daily may be beneficial for narcolepsy. For example, studies show that people taking 400 mg once daily or 200 mg twice daily may experience less daytime sleepiness than those taking 200 mg once daily. Even a total daily dose of 600 mg (given in two doses) may be beneficial. Still, the manufacturer of modafinil recommends a maximum dosage of 400 mg once daily.
Sleep apnea
If you have sleep apnea, you’re likely having trouble breathing and sleeping. This is due to airway blockage that occurs while you lie flat to sleep. Typically, a CPAP (continuous positive airway pressure) machine is recommended to improve breathing during sleep.
But if CPAP isn’t enough, modafinil is considered a first-choice medication for sleep apnea. As with narcolepsy, you should take modafinil in the morning when you first wake up.
Shift work disorder
People who do “shift work” — defined as working outside the hours of 6AM to 7PM — don’t have a typical sleep-wake schedule. This leads to problems with sleep and the ability to stay awake while you work. In shift work disorder, you may be extremely tired while you’re working and have trouble sleeping (insomnia) when you’re not at work.
For shift work disorder, you’ll take modafinil about one hour before you start work. This helps you stay awake during your shift, and makes it less likely for modafinil to cause insomnia when it’s time to sleep.
Are there any dosage adjustments for health conditions?
Yes. If you have severe liver damage or you’re over 65, your healthcare provider may prescribe a lower modafinil dosage.
Dosage for people with liver problems
Modafinil is broken down in the liver. If you have liver damage, modafinil may build up in your body and cause side effects such as headache, nausea, and skin reactions.
If you have severe liver damage, your healthcare provider may decrease your modafinil dose by half. For many people, this means a dose of 100 mg daily. Make sure your provider knows your full medical history before starting modafinil. They’ll help you figure out whether you need a dose reduction.
Dosage for adults over 65
When you get older, the way medications work in your body may change. Your kidneys and liver may not function as well as they used to. This makes it harder for your body to get rid of medications, including modafinil.
If you’re over 65, you may need a lower modafinil dose when you first start taking it. Your healthcare provider can help choose the best dose for you. And if you experience side effects after starting modafinil, let your provider know. This may be a signal that your dose is too high.
What if you miss a dose of modafinil?
If you forget to take modafinil, take it as soon as you remember. But if it’s already close to your bedtime, skip your missed dose and wait until the following day. Then take modafinil at your usual scheduled time. Taking modafinil too close to bedtime can make it hard to sleep.
Even if you miss a dose of modafinil, never take more than one dose at a time. This increases your risk of side effects.
What should you do if you take too much modafinil?
Taking too much modafinil can be dangerous. Symptoms may include:
Insomnia
Confusion
Excitation
Hallucinations
Slow or fast heart rate
High blood pressure
Restlessness, anxiety, and agitation
Gastrointestinal problems such as nausea and diarrhea
If you think you’ve taken too much modafinil, immediately contact your healthcare provider or Poison Control for advice at 1-800-222-1222. If you have any symptoms that feel severe — such as confusion, hallucinations, or a fast heartbeat — seek emergency care or call 911.
The bottom line
Modafinil (Provigil) is an oral tablet that treats excessive sleepiness from narcolepsy, sleep apnea, and shift work disorder. The typical modafinil dosage is 200 mg once daily. The best time to take it depends on what you’re treating. For narcolepsy and sleep apnea, it's usually taken in the morning. But for shift work disorder, you’ll usually take it before your work shift starts. If you have severe liver damage or you’re older than 65, you may need a lower modafinil dosage.
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References
American Academy of Sleep Medicine. (2015). Guideline update: October 2015.
Maski, K., et al. (2021). Treatment of central disorders of hypersomnolence: An American academy of sleep medicine clinical practice guideline. Journal of Clinical Sleep Medicine.
Morgenthaler, T. I., et al. (2006). Practice parameters for the medical therapy of obstructive sleep apnea: Standards of practice committee of the American academy of sleep medicine. Sleep.
Memorial Sloan Kettering Cancer Center. (2022). Patient and caregiver information: Modafinil.
Proficient Rx LP. (2023). Modafinil [package insert].
Schwartz, J. R. L., et al. (2005). Dose effects of modafinil in sustaining wakefulness in narcolepsy patients with residual evening sleepiness. The Journal of Neuropsychiatry.
Sleep Foundation. (2023). Shift work disorder symptoms.
Sleep Foundation. (2023). Shift work disorder: What it is, what causes it, and its potential complications.
Sullivan, S. S. (2012). Current treatment of selected pediatric sleep disorders. Neurotherapeutics.
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