 [ Symptoms ] can lettuce cause me to have diarrhea  we think lettuce is causing diarrhea we do not know what else it could be every week for about a month now if i eat lettuce or my boyfriend eats it it causes diarrhea and stomach pain one time it has even caused us to have stomach flu symptoms [ Disease ] depends on how much has consumed remember lettuce is mostly water and roughage consider also where the lettuce came from  as if a salad bar  there may be bacteria such as e coli or salmonella best to have a stool culture taken if this continues beyond two days people just simply refuse to wash their hands  and contamination spreads also depending on sprays  if it was washed before it was consumed