Modafinil (Provigil)

What it treats

Modafinil is approved by the U.S. Food and Drug Administration for:

• Excessive daytime sleepiness in narcolepsy.
• Shift-work sleep disorder.
• Residual excessive sleepiness in treated obstructive sleep apnea (as adjunct to CPAP or other sleep apnea treatment).

It's used off-label for other causes of pathological sleepiness and, less appropriately, for general fatigue or as a cognitive enhancer, where evidence is thinner and prescribing is not endorsed by clinical guidelines.

How it works

Modafinil is a wake-promoting medication. It's chemically distinct from amphetamine and methylphenidate, and its exact mechanism isn't fully understood. Current understanding is that modafinil is a modest dopamine reuptake inhibitor at the dopamine transporter, and it also influences several other systems, including histamine, orexin, and norepinephrine circuits that maintain wakefulness. That combined effect promotes alertness without producing the same peripheral or euphoric activation as traditional stimulants.

Receptor mechanism (detail)

Modafinil is a weak dopamine transporter (DAT) inhibitor with downstream effects on histamine, orexin, and norepinephrine wake-promoting circuits. The DAT inhibition is real but modest and appears necessary for the wake-promoting effect. Modafinil doesn't cause dopamine release the way amphetamines do, which is one reason its subjective and pharmacologic profile differs from classical stimulants.

Potency and typical dosing pattern

Ranges are typical framework only, not a prescription for any individual.

Narcolepsy and OSA: 200 mg once daily in the morning. Shift-work sleep disorder: 200 mg taken about an hour before the shift starts. Some patients do well on 100 mg; doses above 200 mg per day usually don't add clear benefit.

Half-life is around 15 hours. That relatively long half-life means late-day dosing can disrupt sleep.

Safety monitoring

• Blood pressure and heart rate at baseline and periodically.
• Serious skin reactions. Stevens-Johnson syndrome and toxic epidermal necrolysis have been reported, rarely. New rash, especially with fever or mucous membrane involvement, is a reason to stop and seek urgent care.
• Psychiatric symptoms. Anxiety, agitation, mania, hallucinations, or suicidal thoughts can occur; needs prescriber contact.
• Drug interactions. Modafinil induces CYP3A4 and can reduce levels of many medications, including oral contraceptives.
• Schedule IV controlled substance. Assess for misuse, though liability is lower than with Schedule II stimulants.
• Contraception. Modafinil reduces oral contraceptive effectiveness; a non-hormonal or higher-dose approach is needed during and for a month after use.

What to expect

Common side effects

• Headache, the most common.
• Nausea.
• Nervousness or anxiety.
• Trouble sleeping (especially with late dosing).
• Reduced appetite.
• Dry mouth.
• Dizziness.

If a side effect is bothersome or doesn't settle, that's a conversation for the prescriber.

Serious side effects and warnings

• Serious skin reactions. Stevens-Johnson syndrome and toxic epidermal necrolysis (TEN), as well as drug reaction with eosinophilia and systemic symptoms (DRESS), have been reported. Any new rash, particularly with fever or mucous membrane involvement, means stop and get evaluated urgently.
• Psychiatric symptoms. New anxiety, mania, hallucinations, aggression, or suicidal thoughts need prescriber contact.
• Cardiovascular events. Modafinil can raise blood pressure and heart rate. Chest pain, arrhythmia, or signs of a cardiovascular event need immediate evaluation.
• Angioedema and anaphylaxis, rare.
• Contraceptive failure. Modafinil reduces oral contraceptive effectiveness for the duration of use and for a month after stopping.

Sexual side effects

Modafinil isn't a notable cause of sexual side effects. Some people notice mood or arousal changes; if so, mention it to a prescriber.

Weight, appetite, and sleep

Reduced appetite is common but usually modest. Some weight loss is possible. Sleep timing matters: modafinil's long half-life makes late-day dosing likely to interfere with nighttime sleep.

Starting and dosing basics

This section is general background, not a dosing instruction for any individual. The right dose is a decision for a prescriber.

Modafinil comes as tablets in 100 mg and 200 mg. It's taken once daily in the morning, or an hour before a night shift for shift-work sleep disorder. Dose is not adjusted much beyond the starting range.

Missed doses and interactions

If a morning dose is missed and it's still early in the day, take it. If it's late, skip and resume the next day.

Modafinil is a CYP3A4 inducer and reduces the effectiveness of many medications, including:

• Oral contraceptives. Use a backup non-hormonal method during and for 1 month after stopping.
• Cyclosporine, some HIV medications, some anticonvulsants.

It also modestly inhibits CYP2C19, which can raise levels of some medications (including diazepam, phenytoin, propranolol). Give every prescriber and pharmacist the full medication list.

Stopping and tapering

Modafinil doesn't require a formal taper. Sleepiness will likely return promptly if the underlying sleep disorder is untreated.

Pregnancy and breastfeeding

Modafinil use in pregnancy is generally avoided when possible. There is a signal for intrauterine growth restriction and possible birth defects. Pregnancy registry data is limited, and current guidance leans toward alternatives. Anyone pregnant, planning a pregnancy, or breastfeeding should have this discussion with the prescriber, ideally before conception. Contraceptive planning matters, given modafinil's effect on hormonal contraceptives.

Cost and generic availability

Modafinil is available as a generic and is much less expensive than the brand-name Provigil. Insurance coverage is common for narcolepsy and OSA. Off-label uses are often not covered.

Common questions

Is modafinil a stimulant? It's a wake-promoting medication, and it does have modest dopamine reuptake inhibition. It's chemically distinct from amphetamine and methylphenidate and has a different pharmacologic and subjective profile. Schedule IV rather than Schedule II reflects the lower misuse liability.

Does it work as well as Adderall for ADHD? Modafinil is not FDA-approved for ADHD and evidence for its benefit in ADHD is mixed and modest. Traditional stimulants remain the first-line treatment. Off-label modafinil for ADHD is generally not recommended in clinical guidelines.

Can I take my birth control pill while on modafinil? Modafinil reduces oral contraceptive effectiveness. Use a non-hormonal backup method during use and for 1 month after stopping.

Is it addictive? Its misuse liability is lower than amphetamines or methylphenidate, which is why it's Schedule IV. Some misuse potential exists.

What should I do about a new rash? Stop the medication and contact the prescriber urgently. A new rash with fever, mucous membrane involvement, or spreading skin peeling could be a serious drug reaction.

Questions to ask your prescriber

• What are we hoping this treats, and how will we know it's working?
• If I'm on hormonal contraception, what should I use for backup?
• Which side effects should I expect, and which ones should I call about?
• Which of my other medications does modafinil interact with?
• If I need to stop it, is a taper needed?

Sources

This guide draws on current prescribing information and public health references and current as of June 8, 2026. It is reviewed for clinical accuracy and updated as guidance changes.

• U.S. Food and Drug Administration. Modafinil (Provigil) prescribing information.
• MedlinePlus, U.S. National Library of Medicine. Modafinil.
• American Academy of Sleep Medicine. Clinical Practice Guideline for the Treatment of Central Disorders of Hypersomnolence.
• National Institute of Neurological Disorders and Stroke. Narcolepsy information page.