Possible side effects of Pepto-Bismol include anxiety, confusion, diarrhea and constipation, according to Drugs.com. Stomach pain, vision problems, depression or thirst are other possible side effects. Pepto-Bismol may make some people feel dizzy or lightheaded.
Pepto-Bismol may cause muscle spasms, which are most likely to occur in the back, neck or face. Speaking difficulty, including slurred speech, may occur in those who take Pepto-Bismol.
Pepto-Bismol may cause a severe or continuing headache. It can cause heavy or fast breathing as well as ringing in the ears. Other side effects are possible, and it is important to consult a medical professional if side effects occur.