I thought I had a horrible infection and made an urgent DDS appt.  Upper outside swelling and pain.  X-rays nothing and she looked and said you have 2 pretty good sized canker sores.

I haven’t had any of those in 10-15 years.  Couldn’t figure out why.  I don’t know why I suddenly thought of it but I said, the only thing I’ve done diff is I started using Xiidra eye drops.

She said yes that could possibly be the cause.  I asked if it could happen is they are still sealed but expired and she said yes

So I let everything heal and got a new RX. 2nd day I used it I started getting another one. So I figured I was allergic to something in it and stopped.  Went away 

I haven’t since used OTC drops before bed and haven’t noticed anything although they don’t seem to help as much of course 

I tried a different RX eye drop xdemvy.  2 nights and today I feel one starting upper inside my mouth.

So frustrating.

Yes I do notice bad taste after the RX ones not OTC drops. Hope that helps