Anaphylatic reactions occurs after you have ONCE been exposed to some allergic substance (allergen) which your body recognized as being foreign and the next time you come again in contact with the allergen, your body produces abnormally high amounts of antibodies
against that substance which not only destroys it but also severely affects your blood pressure, heart beat, respiration and consciousness.
Anaphylactic reactions though can occur with any drug are rare with Accutane
and even rarer after taking a medication continuously for months. If u stop the medication for a while and then re-start it again, it may occur but since u have been taking it continuously, it is very unlikely u will have an anaphylactic reaction. You body may develop other immune reactions to the medication with chronic use other than an anaphylactic one.
If u have any more fears see the physician who prescribed it but rest assured, the likelihood of such a reaction after all these months are very very very very very rare. :-)