I confess I know nothing about hyoscyamine, but I've probably spit up gallons of saliva/mucous in the last few months with a tumor blocking my stomach entrance. It is sometimes pretty foul-tasting and altogether a bothersome condition. I carry a plastic hospital mug and Kleenex around with me at all times and have avoided going out in public with the exception of hospital visits--chemo/radiation starts next week. My sympathies to you and your father, but hopefully this too will pass.