Modafinil dosage, forms, and strengths

Modafinil (brand name: Provigil) is a prescription central nervous system (CNS) stimulant and dopamine reuptake inhibitor. It is related to armodafinil, known by its brand name Nuvigil, which tends to last longer but doesn’t start working as fast as modafinil. It helps people with sleep disorders overcome sleepiness and fatigue during the day. 

The FDA has approved modafinil for people diagnosed with narcolepsy, obstructive sleep apnea, and shift work sleep disorder, but healthcare professionals may use it off-label to promote wakefulness in people with other medical conditions. Doses are taken with or without food once daily, either upon waking in the morning or before starting a work shift.

Modafinil forms and strengths

The only available dosage form of modafinil is oral tablets.

• Tablets: 100 mg, 200 mg

Modafinil dosage for adults

Modafinil is typically taken as a 200 mg tablet once daily in the morning or one hour before a work shift. The FDA has approved modafinil to help relieve excessive drowsiness and fatigue in people with narcolepsy, obstructive sleep apnea, and shift work sleep disorder. 

Healthcare professionals may prescribe modafinil off-label to manage sleepiness and fatigue in people with multiple sclerosis, Parkinson’s disease, depression, cancer, or other health conditions. Because of its positive effects on alertness and focus, modafinil may sometimes be prescribed off-label to treat attention deficit hyperactivity disorder (ADHD).

Check our best odafinil prices

Modafinil dosage for narcolepsy

Narcolepsy is a chronic, lifelong neurological condition that affects a person’s ability to stay awake during the day. It’s a rare condition that affects one in 2,000 thousand people. 

As a wakefulness-promoting drug, modafinil is a first-line treatment for excessive daytime sleepiness in people with narcolepsy. It is taken as a single dose in the morning to reduce excessive sleepiness throughout the day. However, it does not treat muscle paralysis (cataplexy) caused by narcolepsy.

• Standard dosage for EDS due to narcolepsy: One 200 mg tablet taken once daily in the morning

• Maximum dosage for EDS due to narcolepsy: 200 mg daily

Modafinil dosage for obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common sleep disorder in which people experience breathing difficulties while asleep. Around 25% to 30% of men and 9% to 17% of women in the U.S. have obstructive sleep apnea that interferes with their ability to sleep through the night. 

For people with moderate or severe OSA, the first-line treatment is to sleep with a CPAP (continuous positive airway pressure) machine and mask. Modafinil is used as an add-on treatment to help people feel less fatigued and tired during the day. As with narcolepsy, modafinil doses are taken once per day in the morning.

While modafinil can reduce feelings of tiredness, it doesn’t treat the underlying problem of blocked airways. For the best results, it’s important to use a CPAP machine effectively for a significant period before starting modafinil.

• Standard dosage for the adjunct treatment of obstructive sleep apnea: One 200 mg tablet taken once daily in the morning

• Maximum dosage for obstructive sleep apnea: 200 mg daily

Modafinil dosage for shift work sleep disorder

Night shift and irregular-hour workers often struggle with sleep because their body clocks don’t match their schedules. About 29% to 38% of these workers face sleep problems, compared to only 6% of day workers. This lack of rest leaves them tired and sleepy on the job, a condition known as shift work sleep disorder.

Modafinil and armodafinil are considered first-line treatments for people with fatigue and sleepiness. These drugs are usually part of a larger treatment plan that involves lifestyle changes, dietary changes, light therapy, and possibly drugs or supplements that help the person fall asleep at bedtime.

Since shift work doesn’t follow normal schedules, people taking modafinil for shift work sleep disorder take one tablet approximately one hour before beginning the shift.

• Standard dosage for shift work sleep disorder: One 200 mg tablet taken one hour before the work shift

• Maximum dosage for shift work sleep disorder: 200 mg daily

Modafinil dosage for children

The FDA has not approved modafinil for pediatric use. The safety and effectiveness of the drug have only been established in people over 18. 

Modafinil dosage restrictions

Modafinil has no dosage restrictions for people with kidney disease, but people with severe liver disease are recommended to take a reduced dose of 100 mg daily. In people with liver disease, the body removes modafinil more slowly, leading to higher levels of the drug in the system. This can increase the risk of side effects.

In older adults, the body might take longer to remove modafinil and its byproducts, which may increase the risk of side effects. Therefore, it’s recommended to use lower doses and keep a close watch on the medication’s effects in older adults. 

Those who are allergic to modafinil or any ingredients in the medication should avoid taking it. If you are also allergic to armodafinil, you should avoid this medication.

How to take modafinil

When taking modafinil, the most important tips to remember are to take the tablets in the morning or one hour before a work shift and take no more than one tablet daily.

• Take this medicine as prescribed. 

• Do not increase the dose or take more than one tablet daily. 

• Take the tablets at the same time each day.

• Do not change the time when tablets are taken without talking to the prescriber first.

• For narcolepsy or sleep apnea, take the day’s dose early in the morning. 

• If used for shift work, take the tablet one hour before the start of the shift.

• Do not take a modafinil dose too close to bedtime.

• Modafinil tablets can be taken with or without food.

• Swallow the tablet whole with a drink of water.

• Store modafinil tablets out of the reach of children at room temperature.

• If you take more than your prescribed dose or if you take an overdose of modafinil, call your doctor or go to the nearest hospital emergency room right away.

Before you start taking modafinil, it’s important to tell your doctor about any health problems you have, such as mental health conditions, heart problems, high blood pressure, or a history of drug or alcohol abuse. Sharing this information can help your doctor decide if modafinil is right for you and keep track of any risks. 

Also, let your doctor know if you are pregnant, planning to become pregnant, or breastfeeding. The effects of modafinil on unborn babies and breast milk aren’t fully known, so discussing these topics with your doctor ensures you get the best care while using this medication.

Modafinil dosage FAQs

How long does it take modafinil to work?

Modafinil usually starts working within one hour of taking a dose. However, the full effects of modafinil might not occur until about two to four hours after the tablet is swallowed. Modafinil tablets can be taken with or without food. However, when a tablet is taken with food, it may take at least an hour longer for the dose to take effect.

How long does modafinil stay in your system?

Modafinil has a half-life of approximately 15 hours, meaning that it takes about this long for the body to reduce the drug's concentration by half. Typically, it takes around three days (or five half-lives) for modafinil to be completely eliminated from the system. The half-life is a key measure that helps determine how long a substance remains active in the body.

What happens if I miss a dose of modafinil?

Ask the prescriber how to handle a missed dose. Generally, a missed dose can be taken when remembered, provided the day is still early. When taken later in the day, a modafinil dose can make it difficult to fall asleep at bedtime. Never take two doses in one day to make up for a missed dose.

How long can you take modafinil?

Modafinil is typically prescribed for 12 weeks or less. However, it may be used as a long-term treatment for people with chronic sleep problems if used under a doctor’s guidance. The medication is typically prescribed for as long as it works and doesn’t cause serious adverse effects. 

How do I stop taking modafinil?

When it’s time to stop taking modafinil, doses do not need to be gradually reduced over time. A sudden discontinuation of modafinil will not provoke withdrawal symptoms. However, daytime drowsiness has been reported to return in people with narcolepsy who stop the drug. 

If there are problems with modafinil or it doesn’t seem to work, please talk to the prescriber before quitting the drug. If excessive daytime sleepiness is still a problem, the healthcare provider may turn to other types of stimulants such as Ritalin (methylphenidate), Adderall (mixed amphetamine salts), or Dexedrine (dextroamphetamine).

What is the maximum dosage for modafinil?

The maximum dosage for modafinil is 200 mg per day in adults. People with severe hepatic impairment or liver problems should not take more than 100 mg daily.

Can you overdose on modafinil?

Taking too much modafinil can be dangerous. While a mild overdose is usually not life-threatening, there have been cases where large overdoses have led to death. If too much modafinil is taken, call a poison control center or go to an emergency room. 

A person who has overdosed on modafinil may become aggressive, confused, disoriented, irritable, agitated, restless, or excited. Other symptoms include insomnia, nausea, diarrhea, shaking, and hallucinations. Heart rate may speed up, slow down, or skip beats alongside other cardiovascular symptoms, such as high blood pressure and chest pain.

What interacts with modafinil?

Modafinil can interact with several medications, but most of the time, people don’t need to change their medications or adjust their dosages. One important interaction to note is that modafinil can make hormonal birth control methods less effective. These birth control methods may include birth control pills, vaginal rings, patches, implants, and IUDs. Women who are using these methods should consider using an additional form of contraception to avoid the risk of pregnancy.

To avoid other possible drug interactions, tell a healthcare provider about any prescription drugs, over-the-counter medications, and supplements being taken.

What happens when you mix modafinil and alcohol?

Mixing modafinil and alcohol may lead to various reactions ranging from blackouts to increased alcohol tolerance. Combining these substances may cause unpredictable effects and carry serious health risks. Therefore, it's recommended to avoid drinking alcohol while taking modafinil.

Is it safe to take modafinil during pregnancy?

Tell a prescribing healthcare professional if you are pregnant or planning to become pregnant. Animal studies have shown modafinil may increase the risk of birth defects. Therefore, healthcare providers may only prescribe it only if the benefits outweigh the risks. 

Is it safe to take modafinil while breastfeeding?

Women who are breastfeeding or planning to breastfeed should talk to their healthcare provider about taking modafinil. It is unclear whether modafinil passes into breast milk, and its effects on nursing infants are not known. For women diagnosed with narcolepsy, healthcare providers may recommend using methylphenidate instead of modafinil while nursing.

What are the side effects of modafinil?

In clinical trials, modafinil’s most common side effects were headache, nausea, nervousness, anxiety, insomnia, and stuffy nose. More serious side effects include psychiatric symptoms, such as mood changes, aggression, and psychosis; heart problems like chest pain, abnormal heartbeat, and trouble breathing; and severe allergic reactions.

Sources

• Modafinil, StatPearls (2023)

• Modafinil, MedlinePlus (2024)

• Modafinil tablet prescribing information, DailyMed (2024)

• Narcolepsy, National Organization for Rare Disorders (2017)

• Obstructive sleep apnea, Johns Hopkins Medicine (2024)

• Obstructive sleep apnea, StatPearls (2024)

• Provigil highlights of prescribing information, U.S. Food and Drug Administration (2015)

• Provigil modafinil tablet prescribing information, DailyMed (2022)

• Shift work hazards, StatPearls (2024)

• Successful lactation after resuming methylphenidate in a woman with narcolepsy, Journal of Clinical Sleep Medicine (2022)