We have written extensively on this topic in the past and if you read our answers on the subject, you can see that there really is no clear answer. Here is a summary of what we have written....

 
The drug manufactures make expiration dates based on their data for drug stability during drug trials. If they have data that a drug is still potent after say 2 years, then they will make the expiration date 2 years. As such,  manufacturers typically use 2- to 3-year expiration dates. The problem with this, is that a drug may be stable for much longer than 2 years but the company doesn't have data on it.

 
FDA tests show that most drugs remain safe and effective long after their expiration date, if kept in their original container or a proper pharmacy container (closed, somewhat protected from light etc...). The FDA started testing military drug supplies 15 years ago. Over 90% of the drugs tested have been found to be safe and effective for many years past their expiration date.

    
 It's very convenient to use shorter term expiration dates for drug manufacturers.  They don't need to perform longer stability tests...and the short dating assures the purchase of new drugs. Manufacturers also say it's safer since people won't hang on to old bottles that don't have current labeling and precautions.


Now, some drugs do degrade very quickly such as nitroglycerin, insulin, mefloquine and others. I don't believe sporanox falls into this category.


So, while it's tough to exactly tell if your drug remains potent, there most likely won't be any harm in taking an expired drug. However, even though it may still be potent, it may not be appropriate due to changes in your condition. Did a doctor say to take this drug or is this a flare up from a previous problem? I always recommend being seen again if you haven't had a check up in awhile...