Venlafaxine is used primarily for the treatment of cataplexy.
Venlafaxine is widely used as an anti-depressant. It is a "generic" drug that is produced by numerous manufacturers. Venlafaxine is not licensed for the treatment of narcolepsy, but is nonetheless commonly prescribed for the treatment of cataplexy by sleep specialists (so-called "off-label prescribing").
Venlafaxine is produced in several different forms, but for the treatment of narcolepsy it is usually administered as a tablet or capsule.
Venlafaxine is manufactured by several different pharmaceutical companies. There should be no difference in the efficacy of these different versions of the drug, except that some forms of venlafaxine are intended to prolong the effect of the drug. Using these will mean that the effect of the drug is spread more evenly through the day and you will need to take the drug less frequently, perhaps only once each day, rather than twice or more. These "extended release" or "controlled release" forms of venlafaxine may have names that include the letters ER, XR, CR or sometimes XL. Venlafaxine tablets or capsules have various strengths. In general, the extended release forms of the drug contain a higher dose, perhaps a whole daily dose in one tablet, whereas the ordinary tablets contain much less drug and are generally taken more than once each day.
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.