The high fat content in peanut butter can lead to indigestion due to bloating caused by excess fat in the upper gastrointestinal tract (via O2 Fitness). Additionally, you could experience stomach pain if you have a sensitivity to certain chemicals present in peanut butter known as salicylates and amines, according to the Food Intolerance Dietitian.
If you have salicylate and amine sensitivity, you can experience a wide array of symptoms, the Food Intolerance Dietitian reports. These include bloating, stomach pain, and diarrhea. It could also present with other symptoms such as foggy thoughts, rashes, and, in children, certain behavior issues. According to Medical News Today, there is no single diagnostic or blood test to confirm a sensitivity to these chemicals. If you suspect that you may be experiencing a reaction to salicylates, discuss it with your doctor. He or she may recommend eliminating certain foods from your diet, including beans, lentils, and peanuts, to see if the symptoms improve.