Hi & Welcome to HCM.
I appreciate your concern for the safety of
Pepto-Bismol.
Yes, Pepto-Bismol should not be taken if you are allergic to Aspirin (acetyl
salicylic acid).
Pepto-Bismol is a combination of compound bismuth with subsalicylate (a derivative of salicylic acid) used to treat acidity related stomach problems like heartburn, indigestion, or symptoms associated with eating or drinking too much.
Since it is chemically related to Aspirin, there is a possibility of causing
allergic reaction which is quite similar to Aspirin like rash with itching, swelling of the lips, face, eyes, wheezing or difficulty in breathing.
So, in view of the above explanation it is better to avoid taking
Pepto Bismol instead you may take safer drugs like antacids or
proton pump inhibitor for your acidity related stomach problems.
Hope to have answered your query.
Regards.