Ibuprofen
"Ibuprofen is wonderful for period pain, takes an hour to work and I take 2 x 200mg tablets every 8 hours.  Have been taking ibuprofen for a few years now and it's always done the job so far, until this week that is. I was admitted to hospital with an immune system that almost shut down because of a reaction to ibuprofen.  I consider myself very lucky that I did a routine blood test and found out this information, was told to stop taking the medicine immediately.  Please be careful even if you've taken this medicine on a number of other occasions as I have done."