The clinical signs of lettuce allergy were usually severe, with anaphylaxis occurring in 18 of the 30 individuals. Other plant foods caused adverse responses in all of the subjects. Lettuce was the only food that produced a positive response in 17 of the 18 patients who experienced an anaphylactic reaction to this food product. Yes, you can be intolerant of lettuce. Lettuce contains many nutrients and minerals that are essential for health. However, some people have allergies or sensitivities to certain ingredients found in lettuce. An example is lactose, which is a sugar present in milk that some people cannot digest. Those people may experience symptoms such as diarrhea, constipation, stomach cramps, and nausea after eating lettuce products containing lactose. If you are allergic to lettuce, stay away from it. If you are not allergic to lettuce but want to avoid getting sick from it, then try not to eat too much of it. Eating more of a food that you are sensitive or allergic to will not make you better; it will just cause problems for your body. Lettuce is a good source of fiber and vitamin C. It also has small amounts of calcium and iron. Women who are pregnant or trying to get pregnant should avoid lettuce due to its high content of oxalic acid.