I get spasms from ibs causing constipation. bentyl (dicyclomine) stops that allowing me to poop but it makes me very irritable. will pepto bismol work instead?

No: You could ask your doctor about trying an alternate medication (hyoscyamine)

Not likely : Pepto bismol (bismuth subsalicylate) is not indicated for abdominal spasms or constipation . If you are having pain with the spasm it may help alleviate that;however , I do not think it will stop the spasms per se. If it does help ...great! I would be cautious in the amount of Pepto bismol (bismuth subsalicylate) you take as it contains salicylate which can be toxic if taken more than recommended .