True or false a smoker may have an upset stomach due to smoking?

True.

Smoking can cause an upset stomach due to several reasons. Nicotine, a major component in cigarettes, can irritate the lining of the stomach, leading to inflammation and discomfort. Additionally, smoking can increase the production of stomach acid, which can further contribute to stomach upset and heartburn. Furthermore, smoking can also affect the normal functioning of the digestive system, leading to nausea and vomiting in some individuals.