I have oral lichen planus and with me it's completely stress-related. It developed when I was doing my last house move, which was unbelievably stressful, and is much better now than it was - I seldom get any bad signs of it.
I believe it is an auto-immune response - worth reading around. It can be triggered by certain foods - tomatoes, almonds and cheese among them. These often raise a blister or two with me.
As for BP meds - I am on Lisinopril, but a very tiny dose of 2.5mcg (is it mcg? or mg) :roll: . There appears to be no relation to the lichen planus.
Two remedies I found out about but didn't try for long were spray-on silver nitrate, or aloe vera gel (the edible sort!). Mine calmed down nicely once I'd got over the move.
You have my sympathy - not a nice condition. Apparently it's incurable, just flares up or subsides, depending on circumstances.
Viv 8)