Headache, nausea, nervousness, anxiety, dizziness, and difficulty sleeping may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor immediately if any of these rare but serious side effects occur: mental/mood changes (e.g., agitation, confusion, depression, abnormal thoughts, hallucinations).

Seek immediate medical attention if any of these rare but very serious side effects occur: chest pain, fast/pounding/irregular heartbeat, signs of infection (e.g., fever, persistent sore throat).A very serious allergic reaction to this drug is rare. However, stop taking this medication and seek immediate medical attention if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), skin blisters/peeling, severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist

Modafinil decreases extreme sleepiness due to narcolepsy and other sleep disorders such as difficult/irregular breathing during sleep (e.g., obstructive sleep apnea/hypopnea syndrome-OSAHS). It is also used to help you stay awake during work hours for people with work schedules that interfere with a normal sleep routine (shift work sleep disorder-SWSD).It is not known how modafinil works to increase wakefulness. It is thought to work by affecting certain chemicals in the brain that control the sleep/wake cycle. Modafinil does not make up for lack of sleep and should not be used to treat tiredness or hold off sleep in people who do not have a sleep disorder.This medication is not recommended for use in children.