Feb 15, - Modafinil: learn about side effects, dosage, special precautions, and more on MedlinePlus. How should this medicine be used? Expand. Includes: indications, dosage, adverse reactions, pharmacology and more. Patients with abnormal levels of sleepiness who take Provigil should be advised. Modafinil. Modafinil, sold under the brand name Provigil among others, is a medication to treat sleepiness due to narcolepsy, shift work sleep disorder, or obstructive sleep apnea (OSA).Trade names: Provigil, Alertec, Modavigil, others.