Modafinil is a "stimulant" that is used to promote wakefulness and reduce excessive daytime sleepiness.
Modafinil is a tablet that usually comes in two different strengths: 100mg or 200mg. The required dose will vary from patient to patient. It may be just 100mg per day or several times that dose. For some, a single 100mg tablet taken shortly after waking in the morning will be sufficient. For others, it may be necessary for the total dose to be greater and to be spread through the day, perhaps taking a top-up tablet in the early afternoon, for instance.
Modafinil is a "generic" drug that is manufactured by several different pharmaceutical companies. The original manufacturer's brand name is Provigil, but you may be supplied with modafinil from another company. There should be no difference in the efficacy of these different versions of the drug. However, some people report variation in the efficacy of modafinil, depending on the manufacturer. As all these generics contain the same quantity of active drug, there is no clear reason why this should be the case. As yet, there has been no research to compare the pharmacology of modafinil produced by different companies.
As with any medication, the drugs used to treat narcolepsy can have side-effects. These can take many forms. They may be relatively minor, such as mild headaches or a dry mouth, or much more serious, such as anxiety or depression. You should check the Patient Information Leaflet (PIL) in the packaging of your medication for more details and if you experience any of these side-effects (or any not on the PIL) you should consult your doctor or pharmacist.
You can also report side effects directly via the Yellow Card Scheme. By reporting side effects, you can help improve the safety of this medicine.